AcknowledgmentsAt MedicineNet.com, a part of the WebMD network, we continue to foster the concept that you, thereaders, are truly interested in understanding health issues and medical concepts. Accordingly, wehave addressed the medical terms in this dictionary with sensitivity to potential concerns of thosewho are acutely or chronically confronting disease or health concerns. We are grateful for yourinterest in health topics as it is a driving force for the development of the Webster’s New WorldMedical Dictionary, Third Edition.On behalf of the MedicineNet.com division of WebMD, we wish to thank the staff at Wiley Publishing,Inc., especially Roxane Cerda and Suzanne Snyder, for bringing this dictionary to those who need it.We also thank the officers of MedicineNet.com, particularly Gene Lu and David Sorenson, who havesupported the development of this dictionary.The excellence of the technical and editorial staffs at MedicineNet.com greatly facilitated this entireproject. Dan Griffith and Michael Cupp provided the unique publishing software that made it all pos-sible. Cynde Lee, Kelly McKiernan, and Tanya Buchanan have performed magnificently in managingthe vast amount of content and communication between authors and editors. David Sorenson hasbeen an inspirational catalyst for motivation and consistent superior quality.William C. Shiel, Jr., MD, FACP, FACR, thanks his children, Cara Shiel Krenn, Daniel, and Timothy fortheir support. He also acknowledges the support and encouragement of his parents, William andVirginia Shiel, as well as his dear mother-in-law, Helen Stark. With infinite gratitude and love hethanks his wife, Catherine, for her support, love, and editing. With gratitude he acknowledges theHerculean efforts of Frederick Hecht, MD, FAAP, FACMG in developing previous editions of this dic-tionary. And, with admiration beyond words, he thanks his dear friend, colleague, and co-founderof MedicineNet.com, Dennis Lee, MD.Melissa Conrad Stöppler, MD wishes to thank her husband, Hubert Stöppler, and her children,Johannes, Anna, and Tilman, for their enduring support, love, and patience. She also gratefullyacknowledges the support and encouragement of her parents, Kathryn B. Conrad and the late HenryE. Conrad, Jr.Thank you all.–William C. Shiel, Jr., MD, FACP, FACR–Melissa Conrad Stöppler, MD
Get Additional Free Content OnlineAs an added bonus to this fully revised third edition of the Webster’s New World ™ Medical Dictionary,you can visit the companion website at www.medterms.com/wnw.You’ll find a free PDF Healthcare Guide to help you get the most out of your personal medical care.You can also listen to podcasts from Dr. William Shiel and Dr. Melissa Stöppler, the co-editors of theWebster’s New World Medical Dictionary, in which they discuss strategies to help you better com-municate with your doctors and caregivers.Editorial StaffCo-Editors-in-Chief Ruchi Mathur, MD, FRCP(C)William C. Shiel, Jr., MD, FACP, FACR www.MedicineNet.comwww.MedicineNet.com Content ManagersMelissa Conrad Stöppler, MD Cynde Leewww.MedicineNet.com Kelly McKiernan www.MedicineNet.comAssistant EditorsDennis Lee, MD Concept Developmentwww.MedicineNet.com David Sorenson Gene LuJay W. Marks, MD www.MedicineNet.comwww.MedicineNet.com
About the AuthorsWilliam C. Shiel, Jr., MD, FACP, FACR, Co-Editor-in-Chief William C. Shiel, Jr., MD, FACP, FACR, received a bache- lor of science degree with honors from the University of Notre Dame. There he was involved in research in radi- ation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his internal medicine resi- dency and rheumatology fellowship at University of California, Irvine. He is board certified in internal med- icine and rheumatology and is a fellow of the American Colleges of Physicians and Rheumatology. Dr. Shiel is in active practice in the field of rheumatology at the Arthritis Center of Southern Orange County, California. He is currently an active associate clinical professor of medicine at University of California, Irvine. He hasserved as chair of the Department of Internal Medicine at Mission Hospital Regional Medical Centerin Mission Viejo, California. Dr. Shiel has authored numerous articles on subjects related to arthri-tis for prestigious peer-reviewed medical journals, as well as many expert medical-legal reviews. Hehas lectured in person and on television both for physicians and the community. He is a contribu-tor for questions for the American Board of Internal Medicine and has reviewed board questions onbehalf of the American Board of Rheumatology Subspecialty. He served on the Medical and ScientificCommittee of the Arthritis Foundation, and he is currently on the Medical Advisory Board of LupusInternational. Dr. Shiel is proud to have served as chief editor for MedicineNet.com since its found-ing in 1996. He was co-editor-in-chief of the first and second editions of Webster’s New WorldMedical Dictionary.
Melissa Conrad Stöppler, MD, Co-Editor-in-Chief Melissa Conrad Stöppler, MD, is a US board-certified anatomic pathologist with subspecialty training in the fields of experimental and molecular pathology. Dr. Stöppler’s educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She com- pleted residency training in anatomic pathology at Georgetown University followed by subspecialty fellow- ship training in molecular diagnostics and experimen- tal pathology. Dr. Stöppler served as a faculty member of the Georgetown University School of Medicine and has also served on the medical faculty at the University of Marburg, Germany. Her research in the area of virus- induced cancers has been funded by the NationalInstitutes of Health as well as by private foundations. She has a broad list of medical publications,abstracts, and conference presentations and has taught medical students and residents both in theUnited States and Germany. Dr. Stöppler was named a fellow of the Alexander von Humboldt Societyin Germany and was a recipient of a Physician Scientist Award from the US National Cancer Institute.Dr. Stöppler currently serves on the Medical Editorial Board of MedicineNet.com, and is the ChiefMedical Editor of eMedicineHealth.com, both WebMD Inc. companies. Her experience also includestranslation and editing of medical texts in German and English. Dr. Stöppler’s special interests inmedicine include family health and fitness, patient education/empowerment, and molecular diag-nostic pathology. She currently resides in the San Francisco Bay area with her husband and theirthree children.Dennis Lee, MD, Assistant EditorDennis Lee, MD, was born in Shanghai, China, and received his college and medical training in theUnited States. He is fluent in English and three Chinese dialects. He graduated with chemistry depart-mental honors from Harvey Mudd College. He was appointed president of AOA society at UCLASchool of Medicine. He underwent internal medicine residency and gastroenterology fellowshiptraining at Cedars-Sinai Medical Center. Board certified in internal medicine and gastroenterology,Dr. Lee is currently a member of Mission Internal Medical Group, a multispecialty medical groupserving southern Orange County, California. Dr. Lee has maintained an interest in technology andmedical education. He is a regular guest lecturer at Saddleback College in Orange County, California.Dr. Lee serves as chair of MedicineNet.com.
Jay W. Marks, MD, Assistant EditorJay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from YaleUniversity School of Medicine and trained in internal medicine and gastroenterology atUCLA/Cedars-Sinai Medical Center in Los Angeles. For 20 years he was associate director of theDivision of Gastroenterology at Cedars-Sinai Medical Center and an associate professor of medicine,in residence, at UCLA. At Cedars-Sinai he co-directed the Gastrointestinal Endoscopy Unit, taughtphysicians during their graduate and postgraduate training, and performed specialized, nonendo-scopic gastrointestinal testing. He carried out Public Health Service–sponsored (National Institutesof Health) clinical and basic research into mechanisms of the formation of gallstones and methodsfor the nonsurgical treatment of gallstones. He is the author of 36 original research manuscripts and24 book chapters. Dr. Marks presently directs an independent gastrointestinal diagnostic unit wherehe continues to perform specialized tests for the diagnosis of gastrointestinal diseases. Dr. Marksserves as medical and pharmacy editor of MedicineNet.com.Ruchi Mathur, MD, FRCP(C), Assistant EditorDr. Mathur received her medical degree in Canada and did her medical residency at the Universityof Manitoba in Internal Medicine. Dr. Mathur is a certified fellow of the Royal College of Physiciansof Canada and is US board certified in internal medicine and endocrinology, diabetes and metabo-lism. She has been the recipient of numerous research grants which have included the AmericanDiabetes Association grant for research in the field of diabetes and gastric dysmotility and theEndocrine Fellows Foundation Grant for Clinical Research. She has an extensive list of medical pub-lications, abstracts, and posters and has given numerous lectures on diabetes. Most recently she hasco-authored the textbook Davidson’s Diabetes Mellitus: Diagnosis and Treatment, published byElsevier. Dr. Mathur has also served as Research Fellow at Cedars-Sinai Medical Center and a clini-cal instructor at UCLA in endocrinology and metabolism. Currently Dr. Mathur is Co-Director of theDiabetes Management Clinic at the Roybal Comprehensive Health Center and Assistant Professor ofMedicine at the Keck School of Medicine, University of Southern California.Contributing AuthorsRonald Adamany, MD, Gastroenterology • Kent Adamson, MD, Orthopedic Surgery • Leon Baginski,MD, Obstetrics & Gynecology • Jerry Balentine, DO, FACOEP, FACEP, Emergency Medicine • EdwardBlock, MD, Gastroenterology • James Bredencamp, MD, Otolaryngology • Yuri Bronstein, MD,Neurology • Rudolph Brutico, MD, Pediatrics • Carolyn Janet Crandall, MD, Internal Medicine &Women’s Health • Howard Crystal, MD, Neurology • John Cunha, DO, Emergency Medicine • EricDaar, MD, Internal Medicine & Infectious Diseases • Andrew A. Dahl, MD, FACS, Opthamology •
Fernando Dangond, MD, Neurology • Charles C.P. Davis, MD, PhD, Emergency Medicine • RoxanneDryden-Edwards, MD, Psychiatry and Mental Health • Jason C. Eck, DO, MS, Orthopaedic Surgery •Steve Ehrlich, MD, Cardiology • Manuel Fernandez, MD, Endocrinology • Robert Ferry, MD,Pediatric Endocrinologist • Michael C. Fishbein, MD, Cardiovascular & Autopsy Pathology • Tse-LingFong, MD, Hepatology • Catherine G. Fuller, MD, Allergy & Immunology • Ronald Gehling, MD,Allergy & Immunolgy • Gus Gialamas, MD, Orthopedic Surgery • Gary W. Gibbon, MD, PulmonaryDisease & Allergy • Mitchell J. Gitkind, MD, Gastroenterology • Vay Liang W. Go, MD, Nutrition •Sandra Gonzalez Gompf, MD, FACP, FIDSA, Infectious Disease • Jayson Goo, ATC, MA, CKTI, HumanPerformance/Corrective Therapy • Daniel L. Gomel, MD, Internal Medicine & Geriatrics • MarkGraber, MD, Family Practice • Harold H. Harsch, MD, Psychiatry • Roza Hayduk, MD, SleepMedicine • Barbara K. Hecht, PhD • Frederick Hecht, MD, FAAP • Standiford Helm III, MD,Anesthesiologist/Pain Management • Kendall Ho, MD, Emergency Medicine • Debra E. Houry, MD,MPH, Emergency Medicine/Women’s Health • Camille Marie Teres Hylton, MD, Ophthamology •David Kaminstein, MD, Gastroenterology • Kenneth Kaye, MD, Pathology • Jillyen E. Kibby, M.A.,CCC-A, Audiology • Harley J. Kornblum, MD, Pediatrics & Neurology • Betty Kovacs, MS, RD,Nutrition • Daniel Lee Kulick, MD, FACC, FSCAI., Internal Medicine & Cardiology • Eric Lee, MD,Gastroenterology • Margaret Lee, DDS, Dentistry • Stacy E. Lee, MD, Allergy & Immunology •Michael Lill, MD, Hematology/Oncology • Arthur H. Loussararian, MD, Inetrnal Medicine &Cardiology • Ralph Maeda, MD, Surgery • Dwight Makoff, MD, Nephrology & Hypertension •Murray Margolis, MD, Internal Medicine • Randy Martin, MD, Pulmonary/Infectious Diseases •James Meaglia, MD, Urology • John Mersch, MD, Pediatrics • Michael Miyamoto, MD, Cardiology •Zab Mohsenifar, MD, Internal Medicine & Pulmonary Diseases • John R. Morris, MD, OrthopedicSurgery • Mim Mulford, MD, Endocrinology • Marty Nettleman, MD, MS, Infectious Disease • MarkScott Noah, MD, Internal Medicine • Omudhome Ogbru, PharmD, Pharmacy • Peter J. Panzarino,Jr. MD, Psychiatry & Behavioral Medicine • David Adam Perlstein, MD, FAAP, Pediatarics • DennisPhilips, MD, Pediatrics • Donald Pratt, MD, Internal Medicine • Stefan M. Pulst, MD, Neurology •J. Bradley Randleman, MD, Opthamology • Donald Rediker, MD, Cardiology • Alan Rockoff, MD,Dermatology • Emmanuel Saltiel, PharmD FASHP, FCCP, Pharmacy • Stephen J. Sanders, M.A., CCC-A,Audiology • Michael Santoro, MD, Gastroenterology • George Schiffman, MD, Pulmonary • LeslieJ. Schoenfield, MD, PhD • Melvin Shiffman, MD, Cosmetic Surgery • Lawrence J. Schwartz, MD,Ophthalmology • Joseph Sciammarella, MD, FACP, FA.CEP, Emergency Medicine • John Sheppard,MD, Ophthalmology and Pharmacology • David Simon, MD, Internal Medicine • Robert Simon, MD,Neurology • Thomas P. Sokol, MD, FACS, FASCRS, Gastroenterology • Mark Sullivan, MD, Urology •Alan Szeftel, MD, Allergy and Immunology/Pulmonary Disease • Bruce Tammelin, MD, PulmonaryDisease • Suzanne Trupin MD, FACOG, Obstetrics and Gynecology • Michael Truong, MD,Endocrinology • Theodore Van Dam, MD, Internal Medicine • John Vierling, MD, Hepatology •Benjamin C. Wedro, MD, FAAEM, Emergency Medicine • Richard Weil, M.Ed., CDE, ExercisePhysiology, Diabetes Educator • Maureen Welker, MSN, NPc, CCRN • Edward J. White, MD, GeneralSurgery • Leslie Williams, EdD, Psychology • Joseph Y. Wu, MD, Internal Medicine & Geriatrics •Marilyn A.D. Yee, PharmD, Pharmacy • David Zachary, MD, Family Medicine
Introductionlexicographer A writer of dictionaries, a harmless drudge.–Samuel Johnson, 1755Like the previous editions, this edition has been conceived and developed by the staff of the healthinformation Web site MedicineNet.com, part of the WebMD Health Network. One of the earliesthealth information sites on the Internet, MedicineNet.com has devoted a number of years to creat-ing an online medical dictionary that now contains a wealth of contemporary medical terms andprovides the broad foundation for this book.To create this new edition of Webster’s New World Medical Dictionary, we have reviewed everyentry in the previous edition and have rewritten and strengthened many of those entries. In addition,we have selected new entries from our online medical dictionary for incorporation into this thirdedition. A unique feature of an online medical dictionary is that it can (and does) evolve rapidly tokeep pace with the changes in medicine. We have taken advantage of this to update Webster’s NewWorld Medical Dictionary.Like all of the medical content from MedicineNet.com, this dictionary was written and edited byphysicians, to be used by anyone and everyone concerned about their own health or the health ofthose who matter to them. All the medical information found on MedicineNet.com has been devel-oped by a network of physicians. The physicians select the topics and review and edit all written con-tent. These physicians also make use of medical specialists and health writers throughout the US.The “About the Authors” pages provide abbreviated biographies of the editors and specialists whocontributed content to the MedicineNet.com online dictionary and this book.Medicine is now advancing with remarkable rapidity on many fronts, and the language of medi-cine is also continually evolving with remarkable rapidity, commensurate with the changes. Today,there is constant need for communication between and among consumers and providers of healthcare. There is consequently a need for a high-quality, contemporary medical dictionary.In the current health care environment, patients and their physicians, nurses, and allied health pro-fessionals must be able to discuss the ever-changing aspects of health, disease, and biotechnology.An accurate understanding of medical terminology can assist communication and improve care forpatients, and it can help to alleviate the concerns of family members and friends.The fact that the content of this dictionary is physician-produced by MedicineNet.com ensures anunusual degree of professional expertise, reliability, and perspective.
As a bonus, this edition includes a companion Web site at www.medterms.com/wnw. There you willfind content not found in the book such as PDF healthcare guides and audio podcasts.We hope that you will find Webster’s New World Medical Dictionary, Third Edition a valuable addi-tion to your family or office library and a source of both information and illumination in any med-ical situation.
that spans the body cavity, just below the lungs. SeeAa also abdominal cavity. abdomen, acute See acute abdomen. abdominal aorta The final section of the aorta, the largest artery in the body, which begins at the diaphragm as a continuation of the thoracic aorta and ends by splitting in two, to form the common iliac arteries. The abdominal aorta supplies oxy- genated blood to all the abdominal and pelvic organs, as well as to the legs. See also aorta.A In genetics, adenine, a member of the adenine- abdominal aortic aneurysm See aneurysm,thymine (A-T) base pair in DNA. abdominal aortic.a- Prefix indicating the absence or depletion of abdominal cavity The cavity within thesomething: for example, aphagia (not eating) or abdomen. This space between the abdominal wallaphonia (voiceless). The related prefix an- is usu- and the spine contains a number of crucial organs,ally used before a vowel, as in anemia (without including the lower part of the esophagus, the stom-blood) and anoxia (without oxygen). ach, small intestine, colon, rectum, liver, gallblad- der, pancreas, spleen, kidneys, adrenal glands,AA 1 Alcoholics Anonymous. 2 Amino acid. ureters, and bladder. See also abdomen.AAAS American Association for the Advancement abdominal guarding Tensing of the abdominalof Science, a professional organization that pub- wall muscles to guard inflamed organs within thelishes the weekly journal Science. abdomen from the pain of pressure upon them.AAFP 1 American Association of Family Abdominal guarding is detected when the abdomenPhysicians, a professional organization for physi- is pressed and is an indication that inflammation ofcians who treat both children and adults. 2 the inner abdominal (peritoneal) surface may beAmerican Academy of Family Physicians, a profes- present due, for example, to appendicitis or diverti-sional organization for physicians who treat both culitis. The tensed muscles of the abdominal wallchildren and adults. automatically go into spasm to keep the tender underlying tissues from being irritated.AAO 1 American Association of Ophthalmology, aprofessional organization. 2 American Association abdominal hysterectomy See hysterectomy,of Orthodontists, a professional organization. 3 abdominal.American Academy of Otolaryngology, a professional abdominal muscle One of a large group of mus-organization. cles in the front of the abdomen that assists in main-AAOS American Academy of Orthopaedic taining regular breathing movements, supports theSurgeons, a professional organization. See also muscles of the spine while lifting, and keeps abdom-orthopaedics. inal organs in place. Abdominal muscles are the tar- get of many exercises, such as sit-ups. AbdominalAAP 1 American Academy of Pediatrics, a profes- muscles are informally known as the abs.sional organization for physicians who treatinfants, children, adolescents, and young adults. abdominal pain Pain in the belly. Abdominal2 American Academy of Pedodontics, a professional pain can be acute or chronic. It may reflect a majororganization. 3 American Academy of problem with one of the organs in the abdomen,Periodontology, a professional organization. 4 such as appendicitis or a perforated intestine, or itAmerican Association of Pathologists, a professional may result from a fairly minor problem, such asorganization. excess buildup of intestinal gas.ab- Prefix indicating from, away from, or off, as in abducens nerve See abducent nerve.abduction (movement of a limb away from the mid- abducent nerve The sixth cranial nerve, whichline of the body) and abnormal (away from normal). emerges from the skull to operate the lateral rectusabdomen The part of the body that contains all muscle. This muscle draws the eye toward the sidethe structures between the chest and the pelvis. The of the head. Paralysis of the abducent nerve causesabdomen, or belly, is anatomically separated from inward turning of the eye.the chest by the diaphragm, the powerful muscle
abduction 2abduction The movement of a limb away from abortion, spontaneous Miscarriage.the midline of the body. The opposite of abductionis adduction. abortive Tending to cut short the course of a dis- ease, as in abortive polio (polio cut short).abductor muscle See muscle, abductor. abortive polio A minor, abbreviated form ofABG Arterial blood gas, a sampling of the blood infection with the polio virus. Full recovery occurslevels of oxygen and carbon dioxide within the in 24 to 72 hours, and the condition does notarteries, as opposed to the levels of oxygen and car- involve the nervous system or permanent disabili-bon dioxide in veins. Typically, the acidity (pH) is ties. See also polio.also simultaneously measured. ABP American Board of Pediatrics, a professionalabiotrophy Loss of function, or degeneration for organization for physicians who treat infants, chil-reasons unknown. dren, adolescents, and young adults.ablate To remove, from a Latin word meaning “to abrasion 1 A wearing away of the upper layer ofcarry away.” See ablation. skin as a result of applied friction force. See also scrape. 2 In dentistry, the wearing away of a toothablation Removal or excision. Ablation is usually surface.carried out surgically. For example, surgicalremoval of the thyroid gland (a total thyroidectomy) abruptio placentae Premature separationis ablation of the thyroid. (abruption) of the placenta from the wall of the uterus, often in association with high blood pres-abnormal Outside the expected norm, or sure or preeclampsia. Abruption is a potentiallyuncharacteristic of a particular patient. serious problem both for mother and fetus because the area where it occurs bleeds and the uterusABO blood group The major human blood begins to contract. Shock may result. See also pla-group system. The ABO type of a person depends on centa; preeclampsia.the presence or absence of two genes, A and B.These genes determine the configuration of the red abs Slang term for the abdominal muscles.blood cell surface. A person who has two A geneshas red blood cells of type A. A person who has two abscess A local accumulation of pus anywhere inB genes has red cells of type B. If the person has one the body. See also boil; pus.A and one B gene, the red cells are type AB. If theperson has neither the A nor the B gene, the red abscess, perianal An abscess next to the anuscells are type O. It is essential to match the ABO sta- that causes tenderness, swelling, and pain on defe-tus of both donor and recipient in blood transfu- cation.sions and organ transplants. abscess, peritonsillar An abscess behind theabortifacient A medication or substance that tonsils that pushes one of the tonsils toward thecauses pregnancy to end prematurely. uvula (the prominent soft tissue dangling from the back of the palate in the back of the mouth). A peri-abortion Premature exit of the products of the tonsillar abscess is generally very painful and asso-fetus, fetal membranes, and placenta from the ciated with difficulty opening the mouth. If auterus. Abortion can be a natural process, as in a peritonsillar abscess is untreated, the infection canmiscarriage; an induced procedure, using medica- spread deep into the neck, causing airway obstruc-tion or other substances that cause the body to tion and other life-threatening complications.expel the fetus; or a surgical procedure thatremoves the contents of the uterus. See also dila- abscess, skin A confined collection of pus in thetion and curettage. skin. The common boil is a type of skin abscess. See also boil.abortion, habitual The miscarriage of three ormore consecutive pregnancies with no intervening abscission To remove tissue by cutting it away, aspregnancies. Habitual abortion is a form of infertil- in surgery. See also resection.ity. Also known as recurrent abortion and multipleabortion. absence of the breast See amastia.abortion, multiple See abortion, habitual. absence of the nipple See athelia.abortion, recurrent See abortion, habitual.
3 ACE inhibitorabsinthe An emerald-green liqueur flavored with accessory nerve The eleventh cranial nerve,extracts of the wormwood plant, licorice, and aro- which emerges from the skull and receives an addi-matic flavorings in an alcohol base. Absinthe was tional (accessory) root from the upper part of themanufactured, commercialized, and popularized in spinal cord. It supplies the sternocleidomastoid andFrance in the late 1700s. It was an extremely addic- trapezius muscles.tive drink. Prolonged drinking of absinthe causesconvulsions, blindness, hallucinations, and mental accessory neuropathy A disease of the acces-deterioration. Absinthe has been banned, but some- sory nerve, paralysis of which prevents rotation ofthing of its taste is still available in such drinks as the head away from one or both sides and causesGreek ouzo and French pastis. Homemade absinthe the shoulder to droop. Damage can be confined tomay still be illicitly consumed in some areas. the accessory nerve, or it may also involve the ninth and tenth cranial nerves, which exit the skullabsolute CD4 count The number of “helper” T- through the same opening.lymphocytes in a cubic millimeter of blood. Theabsolute CD4 count is frequently used to monitor accessory placenta See placenta, accessory.the extent of immune suppression in persons withHIV because with HIV, this number declines as the acclimatization to altitude The process ofinfection progresses. Also known as T4 count. adapting to the decrease in oxygen concentration at a specific altitude. A number of changes must takeabsorption Uptake. For example, intestinal place for the body to operate with decreased oxy-absorption is the uptake of food (or other sub- gen. These changes include increasing the depth ofstances) from the digestive tract. respiration; increasing the pressure in the pul- monary arteries, forcing blood into portions of theabstinence The voluntary self-denial of food, lung that are normally not used at sea level; manu-drink, or sex. Today, abstinence most commonly facturing additional oxygen-carrying red bloodrefers to denial of one’s sexual activity. cells; and manufacturing extra 2, 4-DPG, a sub- stance that facilitates the release of oxygen fromabuse, child See child abuse. hemoglobin to the body tissues. Acclimatization generally takes 1 to 3 days and occurs after anyabuse, elder See elder abuse. significant altitude change above 1,220 meters (approximately 4,000 feet). Acclimatization is thea.c. Abbreviation of the Latin phrase ante cibum, body’s natural means of correcting altitude sicknessmeaning “before meals.” See also Appendix A, and the rate of acclimatization depends on the alti-“Prescription Abbreviations.” tude, rate of ascent, and individual susceptibility.AC joint See acromioclavicular joint. accoucheur A male obstetrician. An accoucheuse is a woman obstetrician, or sometimesacanthosis nigricans A skin condition charac- a midwife.terized by dark, thickened, velvety patches, espe-cially in the folds of skin in the armpit, groin, and ACE Angiotensin converting enzyme. ACE convertsback of the neck. It can occur with endocrine dis- an angiotensin to its activated form, angiotensin II,eases such as Cushing disease and diabetes mellitus, enabling it to function. Angiotensin II constrictsfrom tumors of the pituitary gland, underlying malig- blood vessels and elevates blood pressure.nancies, certain drugs, and as a genetic disorder. Itis most common in people who have insulin resist- ACE inhibitor A drug that inhibits ACE. Using anance—those whose body is not responding cor- ACE inhibitor relaxes the arteries, not only loweringrectly to the insulin that they make in their pancreas. blood pressure but also improving the pumping effi- ciency of a failing heart and improving cardiac out-acapnia Lower than normal level of carbon dioxide put in patients with heart failure. ACE inhibitors arein the blood. The opposite of acapnia is hypercapnia. therefore used for blood pressure control and con- gestive heart failure. ACE inhibitors includeaccelerated phase of leukemia Chronic myel- benazepril (brand name: Lotensin), captoprilogenous leukemia that is progressing. In this phase, (brand name: Capoten), lisinopril (brand names:the number of immature, abnormal white blood Zestril, Prinivil), quinapril (brand name: Accupril),cells in the bone marrow and blood is higher than and ramipril (brand name: Altace). Interestingly,in the chronic phase, but not as high as in the blast ACE inhibitors were originally developed from thephase. venom of a Brazilian viper snake.
acentric chromosome 4acentric chromosome A chromosome that is Achilles tendon One of the longest tendons inlacking a centromere (a specialized region of the the body, a tough sinew that attaches the calf musclechromosome to which spindle fibers attach during to the back of the heel bone (calcaneus). The namecell division). As a result, an acentric chromosome comes from Greek mythology: The hero Achillesis lost when the cell divides. See also centromere. was invulnerable to injury except for his heel, which proved his downfall when it was pierced by Paris’saceruloplasminemia See ceruloplasmin arrow. It has also proved, literally, to be the down-deficiency. fall of many athletes who have experienced the sud- den pain of its rupture.acetabulum The cup-shaped socket of the hipjoint. The acetabulum is a feature of the pelvis. The Achilles tendonitis Inflammation in the tendonhead (upper end) of the femur (thighbone) fits into of the calf muscle, where it attaches to the heelthe acetabulum and articulates with it, forming a bone. Achilles tendonitis causes pain and stiffness atball-and-socket joint. the back of the leg, near the heel. Achilles tendonitis can be caused by overuse of the Achilles tendon,acetaminophen A nonaspirin pain reliever or overly tight calf muscles or Achilles tendons, excessanalgesic. Acetaminophen may be given alone to uphill running, a sudden increase in the intensity ofrelieve pain and inflammation or it may be com- training or the type of shoes worn to run, or wearingbined with other drugs, as in some migraine med- high heels at work and then switching to a lower-ications, which contain acetaminophen, a heeled workout shoe. Achilles tendonitis causesbarbiturate, and caffeine. pain, tenderness, and often swelling over the Achilles tendon. There is pain on rising up on the toes andacetone A volatile liquid used as an industrial pain with stretching of the tendon. The range ofsolvent. Acetone is also one of the ketone bodies motion of the ankle may be limited. Treatmentthat is formed when the body uses fat instead of glu- includes applying ice packs to the Achilles tendon,cose (sugar) for energy. The formation of acetone is raising the lower leg, and taking an anti-inflamma-usually a sign that cells lack insulin or cannot effec- tory medication. In some severe cases of Achillestively use the insulin that is available, as occurs in tendonitis, a cast may be needed for several weeks.diabetes. Acetone is excreted from the body in the A heel lift insert may also be used in shoes to preventurine. future overstretching of the Achilles tendon. Exerting rapid stress on the Achilles tendon when it isacetone breath The breath of a person with inflamed can result in rupture of the tendon.excessive acetone in their body. Acetone breathsmells fruity and is a telltale sign of significant dia- achlorhydria A lack of hydrochloric acid in thebetes. See also diabetes mellitus. digestive juices in the stomach.acetylcholine A neurotransmitter released by achondroplasia A genetic disorder of bonenerves that is essential for communication between growth and the most common cause of short staturethe nerves and muscles. with disproportionately short arms and legs (known as dwarfism). The individual has a large head withacetylsalicylic acid See aspirin. a prominent forehead (frontal bossing); underde- velopment (hypoplasia) of the midface, with cheek-achalasia A disease of the esophagus that mainly bones that lack prominence; and a low nasal bridgeaffects young adults. Abnormal function of nerves with narrow nasal passages. The fingers are short,and muscles of the esophagus causes difficulty swal- and the ring and middle fingers diverge to give thelowing and sometimes chest pain. Regurgitation of hand a trident (three-pronged) appearance. Theundigested food can occur, as can coughing or brain is entirely normal in people with achon-breathing problems related to entry of food material droplasia, but complications can damage the braininto the lungs. The underlying problems are weak- and spinal cord. Achondroplasia is an autosomalness of the lower portion of the esophagus and fail- dominant trait, affecting boys and girls equally. Mosture of the lower esophageal sphincter to open and cases are due to new gene mutations that appear forallow passage of food. Diagnosis is made by an X- the first time in the affected child. Achondroplasia isray, endoscopy, or esophageal manometry. caused by mutation in the fibroblast growth factorTreatment includes medication, dilation (stretch- receptor-3 gene (FGFR3), and prenatal diagnosis ising) to widen the lower part of the esophagus, and possible. See also dwarfism; dwarfism, hydro-surgery to open the lower esophagus. A fairly recent chondroplastic.approach involves injecting medicines into thelower esophagus to relax the sphincter.
5 acrocyanosisacid, pantothenic Vitamin B5. See also ACOG American College of Obstetricians andAppendix C, “Vitamins.” Gynecologists, a professional organization for women’s health care providers that also does advo-acid indigestion Excessive secretion of cacy work to improve the care of female patients.hydrochloric acid by the stomach cells. Medicallyknown as hyperchlorhydria. Sometimes used inter- acoustic nerve The eighth cranial nerve which ischangeably with heartburn. See also heartburn. concerned with hearing, balance, and head posi- tion. It branches into two parts—a cochlear partacid phosphatase An enzyme that acts to liber- that transmits sound reception for hearing and aate phosphate under acidic conditions and is made vestibular part that senses balance and head posi-in the liver, spleen, bone marrow, and prostate tion. Also known as the vestibulocochlear nerve.gland. Abnormally high serum levels of acid phos-phatase may indicate infection, injury, or cancer of acquired Not inherited, or present at birth (con-the prostate. genital), but developing after birth. For example, AIDS is an acquired, not an inherited, form ofacidophilus Bacteria found in yogurt with “live immune deficiency.cultures” that can help restore supportive bacteriato an intestinal tract whose normal bacterial popu- acquired immunodeficiency disease Seelation (flora) has been disturbed by disease or AIDS.antibiotics. Eating yogurt with acidophilus may alsobe useful in preventing overgrowth of yeast acquired mutation A genetic change that occurs(Candida) in the intestinal tract, mouth (thrush), in a single cell after the conception of an individual.and vagina. See also probiotic. That change is then passed along to all cells descended from that cell. Acquired mutations areacidosis Too much acid in the blood and body. involved in the development of cancer.Acidosis is an abnormal condition resulting fromthe accumulation of acid or the depletion of alkaline acral-lentiginous melanoma See melanoma,reserves. The pH of a body with acidosis is below acral-lentiginous.normal. For a person with diabetes, this can lead todiabetic ketoacidosis. The opposite of acidosis is acrocentric chromosome A chromosome inalkalosis. See also pH. which the centromere is located quite near one end of the chromosome. Humans normally have fiveACL Anterior cruciate ligament. pairs of acrocentric chromosomes. Down syndrome is caused by an extra acrocentric chromosomeacne Localized skin inflammation resulting from (chromosome 21).overactivity of the oil glands at the base of hair folli-cles or as a response to contact with irritating sub- acrocephalosyndactyly An inherited disorderstances. See also acne vulgaris. characterized by abnormalities of the skull, face, hands, and feet. It begins with premature closure ofacne rosacea See rosacea. some sutures of the skull (craniosynostosis) and results in a tall peaked head, shallow eye sockets,acne vulgaris The common form of acne, in and underdeveloped cheekbones. With acro-teens and young adults, that is due to overactivity of cephalosyndactyly, fingers and toes are fused (syn-the oil (sebaceous) glands in the skin that become dactyly), and the thumbs and big toes have broadplugged and inflamed. Acne typically develops when ends. Acrocephalosyndactyly is an autosomal domi-the oil glands come to life around puberty and are nant trait that affects boys and girls. A parent canstimulated by male hormones that are produced in transmit the gene for the disorder, or it can occurthe adrenal glands of both boys and girls. due to a new mutation. Surgery is often useful toTreatments include keeping the skin clean and correct the abnormalities of the skull, face, hands,avoiding irritating soaps, foods, drinks, and cosmet- and feet. See also Apert syndrome; Crouzonics. Severe acne and acne in those who are prone to syndrome.scarring can be treated with topical creams and oralmedications. Skin damaged by acne can be acrochordon See skin tag.improved with treatment by a dermatologist orfacial technologist using dermabrasion (sanding), acrocyanosis Blueness of the hands and feet,removal of scar tissue via laser, and chemical peels. usually due to inadequate circulation.Also known as pimples.
acrodermatitis enteropathica 6acrodermatitis enteropathica A progressive, active euthanasia The active acceleration of ahereditary disease of children, characterized by the terminally ill patient’s death by use of drugs or othersimultaneous occurrence of skin inflammation means. Currently, active euthanasia is openly prac-(dermatitis) and diarrhea. The skin on the cheeks, ticed in the Netherlands and in the US state ofelbows, and knees is inflamed, as is tissue about the Oregon. The patient’s request to the physician mustmouth and anus. There is also balding of the scalp, be voluntary, explicit, and carefully considered, andeyebrows, and lashes; delayed wound healing; and it must be made repeatedly. Moreover, the patient’srecurrent bacterial and fungal infections due to suffering must be unbearable and without anyimmune deficiency. The key laboratory finding is an prospect of improvement. Suicide for other rea-abnormally low blood zinc level, reflecting impaired sons, whether irrational or rational, is not activezinc uptake. Treatment with zinc by mouth is cura- euthanasia. The forced killing of an ill or disabledtive. Acrodermatitis enteropathica is an autosomal person, as has occurred in eugenics programs, isrecessive disorder. See also deficiency, zinc; zinc. also not active euthanasia. And although medica- tions administered for pain relief may hasten death,acromegaly See gigantism, pituitary. aggressive pain relief is a normal medical decision in terminal care, not in active euthanasia. See alsoacromioclavicular joint A gliding joint located assisted suicide; eugenics; euthanasia.between the acromion (a projection of the scapulathat forms the point of the shoulder) and the clavi- active immunity Immunity produced by thecle (the collar bone). It is served and supported by body in response to stimulation by a disease-caus-the capsular, superior, and inferior acromioclavicu- ing organism or other agent.lar ligaments; the articular disk; and the coraco-clavicular (trapezoid and conoid) ligaments. activities of daily living Things that a personAbbreviated AC joint. normally does during a day, including self-care (eating, bathing, dressing, grooming), work, home-acrosyndactyly A condition in which a person making, and leisure. The ability or inability to per-has fused or webbed fingers or toes. Acrosyndactyly form these activities can be used as a practicalcan be partial or complete, and it can usually be measure of ability or disability, and it may be usedcorrected via surgery. It is associated with several by insurers and HMOs as a rationale for approvingbirth defect syndromes. See also Apert syndrome. or denying physical therapy or other treatments. Abbreviated ADL.ACS American College of Surgeons, a professionalorganization that administers standards of practice acuity, auditory The clearness of hearing, afor surgeons. Those who meet the group’s standards measure of how well a person hears.can call themselves Fellows of the ACS. acuity, visual The clearness of vision, a measureactinic Referring to the ultraviolet (UV) rays from of how well one sees.sunlight and UV lamps. Sunburn is an actinic burn.An actinic keratosis is a skin lesion that is the con- acuity test, visual The familiar eye chart test,sequence of chronic sun exposure. which measures how well a person can see at vari- ous distances.actinic keratosis Rough, scaly patches of skinthat are considered precancerous and are due to acupressure The application of pressure on spe-sun exposure. Prevention is to cut sun exposure and cific points on the body to control symptoms suchwear sunscreen. Treatments include performing as pain or nausea. Similar in concept to acupunc-cryosurgery (freezing with liquid nitrogen), cutting ture, but without needles. See also acupuncture.the keratoses away, burning them, putting 5-fluo-rouracil on them, and using photodynamic therapy acupuncture The practice of inserting needles(injecting into the bloodstream a chemical that col- into specific points on the body with a therapeuticlects in actinic keratoses and makes them more sen- aim, such as to reduce pain or to induce anesthesiasitive to destruction by a specialized form of light). without the use of drugs. Traditional ChineseAlso known as solar keratosis and senile keratosis. acupuncturists say the practice unblocks the flow of a life force called ch’i; Western researchers believeactivated charcoal Charcoal that has been acupuncture may affect production of endorphins,heated to increase its ability to absorb molecules. the body’s natural painkillers. In 1997, the NationalActivated charcoal is used to help relieve intestinal Institutes of Health (NIH) issued a consensus state-gas. It is also used to filter and purify liquids, to ment stating that “There is sufficient evidence ofabsorb poisons (as in gas mask filters), and in emer- acupuncture’s value to expand its use into conven-gency situations to neutralize swallowed poisons. tional medicine.” See also acupressure.
7 acute myocardial infarctionacupuncturist A person skilled in the practice of treated, progresses quickly. In acute leukemia, theacupuncture, who may or may not be credentialed leukemic cells are not able to mature properly.by an accrediting body. acute membranous gingivitis A progressiveacute Of short duration, rapid, and abbreviated in and painful infection of the mouth and throat due toonset. A condition is termed acute in comparison to the spread of infection from the gums. Symptomsa subacute condition, which lasts longer or changes include ulceration, swelling, and sloughing off ofless rapidly; or a chronic condition, which may last dead tissue from the mouth and throat. Certainalmost indefinitely, with virtually no change. Each germs (including fusiform bacteria and spiro-disease has a unique time scale: An acute myocar- chetes) have been thought to be involved, but thedial infarction (heart attack) may last a week, actual cause is not yet known. Like most otherwhereas an acute sore throat may last only a day or poorly understood diseases, acute membranoustwo. See also chronic. gingivitis goes by many other names, including acute necrotizing ulcerative gingivitis, fusospirillaryacute abdomen Medical shorthand for the acute gingivitis, fusospirillosis, fusospirochetal gingivitis,onset of abdominal pain. A potential medical emer- necrotizing gingivitis, phagedenic gingivitis, trenchgency, an acute abdomen may reflect a major prob- mouth, ulcerative gingivitis, ulcerative stomatitis,lem with one of the organs in the abdomen, such as Vincent angina, Vincent gingivitis, Vincent infection,appendicitis (inflamed appendix), cholecystitis and Vincent stomatitis.(inflamed gallbladder), a perforated ulcer in theintestine, or a ruptured spleen. acute mountain sickness The physical effect of being in a high-altitude environment. Abbreviatedacute esophageal stricture See esophageal AMS, it is common at altitudes above 2,440stricture, acute. meters (approximately 8,000 feet). Three-fourths of people have mild symptoms of AMS at altitudes overacute fatty liver of pregnancy Abbreviated 3,048 meters (approximately 10,000 feet).AFLP, liver failure in late pregnancy, usually of Occurrence depends on the altitude, rate of ascent,unknown cause. Symptoms include nausea and and individual susceptibility. Symptoms begin 12 tovomiting, abdominal pain, yellowing of the skin and 24 hours after arrival at a new altitude and includeeyes (jaundice), frequent thirst (polydipsia), headache, dizziness, fatigue, shortness of breath,increased urination (polyuria), headache, and loss of appetite, nausea, disturbed sleep, and gen-altered mental state. Laboratory features of AFLP eral malaise. These symptoms tend to worsen atinclude low blood sugar (hypoglycemia), elevated night, when the respiratory drive is decreased.liver enzymes, and low levels of blood platelets. Symptoms should subside within 2 to 4 days,Untreated AFLP can cause complete liver failure, and can be treated by using pain medications suchbleeding due to impaired blood clotting, and death as aspirin. Acetazolamide (brand name: Diamox)of the mother and fetus. AFLP is treated by deliver- can also be used to minimize symptoms and may being the baby as soon as possible, often by inducing taken as a preventive measure. Moderate AMS hasearly labor. It usually subsides after delivery and the same symptoms as AMS, but the headaches can-does not occur in subsequent pregnancies. In some not be relieved with medication, and both breathingcases AFLP is associated with an abnormality of and coordinated movements become difficult. Thefatty-acid metabolism: a deficiency of the enzyme only remedies are advanced medications andlong-chain-3-hydroxyacyl-CoA dehydrogenease descent to lower altitudes. Severe AMS causes great(LCHAD). The mother and father have half the nor- shortness of breath at rest, inability to walk,mal LCHAD activity, and the fetus has no LCHAD decreased mental status, and fluid buildup in theactivity. This metabolic disease in the baby’s liver lungs. Severe AMS requires immediate descent tocauses the fatty liver disease in the mother. lower altitudes: 610 to 1,220 meters (approxi- mately 2,000 to 4,000 feet). See also acclimati-acute HIV infection See HIV infection, acute. zation to altitude.acute idiopathic polyneuritis See Guillain- acute myelogenous leukemia See leukemia,Barre syndrome. acute myeloid.acute illness A disease with an abrupt onset and, acute myeloid leukemia See leukemia, acuteusually, a short course. myeloid.acute leukemia Cancer of the blood cells that acute myocardial infarction A heart attack thatcharacteristically comes on suddenly and, if not occurs when the heart muscle is suddenly deprived
acute nonlymphocytic leukemia 8of circulating blood. Abbreviated AMI. See also ad- Prefix indicating toward or in the direction of.heart attack. For example, adduction is the movement of a limb toward the midline of the body, and adrenal literallyacute nonlymphocytic leukemia See means “toward the kidney.”leukemia, acute myeloid. ad lib Abbreviation of the Latin phrase ad libi-acute otitis media Painful inflammation of the tum, meaning “as much as one desires” or “at yourmiddle ear, typically with fluid in the middle ear, discretion.” See also Appendix A, “Prescriptionbehind a bulging eardrum or a perforated eardrum, Abbreviations.”often with drainage of pus. The customary treatmentis antibiotics for 7 to 10 days. After antibiotic treat- ADA 1 American Dental Association, a professionalment, some children are left with fluid in the middle organization for dentists. Its Council on Dentalear, which can cause temporary hearing loss. In Education and Commission on Dental Accreditationmost children, the fluid eventually disappears spon- are responsible for accrediting schools of dentistrytaneously. If a child has a bulging eardrum and is and allied professions. 2 American Diabetesexperiencing severe pain, a myringotomy (surgical Association, a nonprofit health organization thatincision of the eardrum) to release the pus may be sponsors diabetes research, provides informationdone. Tubes may be placed in the ear to drain fluid. about diabetes and diabetes prevention to patientsSee also ear infection. and others, and advocates for improved treatment of people with diabetes. 3 Adenosine deaminase.acute peritonitis See peritonitis, acute. Adam’s apple The familiar feature on the front ofacute respiratory distress syndrome the neck that is the forward protrusion of the thy-Respiratory failure of sudden onset due to fluid in roid cartilage, the largest cartilage of the larynx. Itthe lungs (pulmonary edema), following an abrupt tends to enlarge at adolescence, particularly inincrease in the permeability of the normal barrier males. It is usually said to take its name from thebetween the capillaries in the lungs and the air sacs. extrabiblical story that a piece of the forbidden fruitThe muscles used in breathing are forced to work stuck in Adam’s throat.harder, causing labored and inefficient breathing.An abnormally low level of oxygen in the blood ADD 1 Attention deficit disorder. 2 Adenosine(hypoxemia) occurs. The types of acute lung injury deaminase deficiency.that may lead to ARDS include, but are not limitedto, aspiration of food or other items into the lungs, addiction An uncontrollable craving, seeking,inhalation of a toxic substance, widespread infec- and use of a substance such as alcohol or anothertion of the lungs, blood infection (sepsis), and near- drug. Dependence is such an issue with addictiondrowning. Treatment frequently involves temporary that stopping is very difficult and causes severeuse of a mechanical ventilator to help the patient physical and mental reactions.breathe. Addison’s anemia See anemia, pernicious.acute thrombocytopenic purpura Suddenonset of low blood platelet levels, with bleeding into Addison’s disease Chronic underfunction of thethe skin and elsewhere. Abbreviated ATP. ATP can outer portion of the adrenal gland, most commonlyhave many causes; for example, it can be a poten- due to autoimmune destruction. Other causestially serious complication during the acute phase of include physical trauma to the adrenal gland, hem-measles infection. orrhage, tuberculosis, and destruction of the pitu- itary gland cells that secrete adrenocorticotropicacute-phase protein A protein whose plasma hormone (ACTH), which normally controls theconcentrations increase during certain inflamma- adrenal gland. Addison’s disease is characterized bytory disorders. Perhaps the best-known acute-phase bronzing of the skin, anemia, weakness, and lowprotein is C-reactive protein (CRP). blood pressure.acyclovir A potent antiviral drug or medication adducted thumbs Clasped thumbs, caused by(brand name: Zovirax) that works against several absence of the extensor pollicis longus and/or bre-human herpes viruses, Epstein-Barr virus, herpes vis muscles to the thumb. When associated withzoster, varicella (chickenpox), cytomegalovirus, mental retardation, it is part of an X-linked syn-and other viruses. It is part of the AIDS drug AZT. drome that affects mainly boys. See MASA syn-See also AZT. drome.
9 adjuvantadduction Movement of a limb toward the mid- first successful gene therapy for this condition inline of the body. The opposite of adduction is abduc- humans was done in 1990, by infusing patients withtion. genetically engineered blood cells.adductor muscle See muscle, adductor. adenosine triphosphate A nucleotide com- pound that is of critical importance for the storageadenine A nucleotide member of the base pair of energy within cells and the synthesis of RNA.adenine-thymine (A-T) in DNA. Abbreviated ATP.adenitis Inflammation of a gland. adenovirus One of a group of viruses that can cause infections of the lung, stomach, intestine, andadenocarcinoma A cancer that develops in the eyes. Symptoms resemble those of the commonlining or inner surface of an organ and usually has cold. There are no effective medications for treatingglandular (secretory) properties. More than 95 per- adenovirus infection. Adenovirus infection typicallycent of prostate cancers are adenocarcinomas. does not cause death or permanent problems. More than 40 types of adenoviruses have been recog-adenoid A mass of lymphoid tissue in the upper nized, all of which are extremely tiny. Adenovirusespart of the throat, behind the nose. When the ade- are being used in research as a vehicle for genenoids are enlarged due to frequent infections, therapy and as a vector for vaccines.breathing through the nose may become difficult.Surgical removal may be done, often accompanied ADH Antidiuretic hormone.by removal of the tonsils. Also known as pharyngealtonsil. ADH secretion, inappropriate A condition that results in the inability to produce dilute urine andadenoidectomy The surgical removal of the ade- imbalance of fluids and electrolytes in the body, par-noids. ticularly lowering blood sodium. Symptoms include nausea, vomiting, muscle cramps, confusion, andadenoiditis Infection of the adenoids. convulsions. This syndrome may occur with oat-cell lung cancer, pancreatic cancer, prostate cancer, andadenoma A benign tumor that arises in or resem- Hodgkin’s disease, among other disorders. Alsobles glandular tissue. If an adenoma becomes can- known as syndrome of inappropriate ADH secretioncerous, it is called an adenocarcinoma. or SIADH.adenomyoma A nodule that forms around ADHD Attention deficit hyperactivity disorder.endometrial tissue in cases of adenomyosis. Seeadenomyosis. adhesion The union of two opposing tissue sur- faces. This term is often used to refer to the sides ofadenomyosis A common, benign condition of a wound, as well as to scar tissue strands that canthe uterus in which the endometrium (the inner form at the site of a previous operation, such asuterus) grows into the adjacent myometrium (the within the abdomen after a laparotomy.uterine musculature located just outside theendometrium). The myometrium may respond to adhesive capsulitis A condition in which a per-this intrusion with muscular overgrowth. If an son has constant severe limitation of the range ofisland of endometrial tissue is contained within the motion of the shoulder due to scarring around themyometrium, it forms an adenomyoma. Also known shoulder joint. Adhesive capsulitis is an unwantedas endometriosis interna, endometriosis uterina, consequence of rotator cuff disease that involvesadenomyosis uteri, and adenomyometritis. damage to the rotator cuff. The affected joint is characteristically painful and tender to palpation.adenopathy Large or swollen lymph nodes. Physical therapy and cortisone injections are oftenLymph nodes can become enlarged as a result of helpful. Surgery is used in advanced cases. Alsoinflammatory diseases, infection, or cancer. known as frozen shoulder.Synonymous with lymphadenopathy. adipose Fatty. Adipose refers to tissue made up ofadenosine deaminase An enzyme that plays a mainly fat cells such as the yellow layer of fatkey role in salvaging purine molecules. Abbreviated beneath the skin.ADA. adiposis dolorosa See Dercum disease.adenosine deaminase deficiency An autoso-mal recessive genetic condition that results in adjuvant A substance that helps and enhancessevere combined immunodeficiency disease. The the effect of a drug, treatment, or biologic system.
adjuvant chemotherapy 10adjuvant chemotherapy Chemotherapy given directives include the living will, power of attorney,after removal of a cancerous tumor to further help and health care proxy. See also DNR.in treatment. Many chemotherapy drugs are mosteffective after the majority of the tumor has been adverse event In pharmacology, any unexpectedremoved. or dangerous reaction to a drug or vaccine.ADLs Activities of daily living. AED See automated external defibrillator.admitting physician The doctor responsible for aer-, aero- Prefix indicating air or gas, such asadmitting a patient to a hospital or other inpatient aerogastria (excess stomach gas).health facility. aerobic Oxygen-requiring. Aerobic bacteria needadnexa In gynecology, the appendages of the oxygen to grow. Aerobic exercise requires the heartuterus, namely the ovaries, the Fallopian tubes, and and lungs to work harder to meet the body’sthe ligaments that hold the uterus in place. increased oxygen demand.adrenal gland A small gland located on top of aerobic exercise Brisk exercise that promotesthe kidney. The adrenal glands produce hormones the circulation of oxygen through the blood and isthat help control heart rate, blood pressure, the way associated with an increased rate of breathing.the body uses food, the levels of minerals such as Examples include running, swimming, and bicy-sodium and potassium in the blood, and other func- cling.tions particularly involved in stress reactions. aerophagia Literally, eating air, from the Greekadrenal medulla See medulla, adrenal. words aer, meaning “air,” and phagein, meaning “to eat.” Aerophagia is a common cause of stomachadrenaline A stress hormone produced within gas. Everyone swallows small amounts of air whenthe adrenal gland that quickens the heart beat, eating or drinking. However, activities such as rapidstrengthens the force of the heart’s contraction, and eating or drinking, gum chewing, smoking, andopens up the bronchioles in the lungs, among other wearing ill-fitting dentures may cause a significanteffects. The secretion of adrenaline is part of the increase in swallowed air.human “fight or flight” response to fear, panic, orperceived threat. Also known as epinephrine. aerosinusitis Painful sinus troubles due to changing atmospheric pressures. Aerosinusitis isadult hemoglobin See hemoglobin A. the cause of sinus pain when going up or down in a plane. Also known as barosinusitis and sinus baro-adult-onset diabetes Non-insulin-dependent, trauma.or type 2, diabetes, the most common form of dia-betes mellitus. Unlike patients with insulin-depend- aerosol A fine spray or mist. Medications inent, or type 1, diabetes, in whom the pancreas makes aerosol form can be administered via a nebulizerno insulin, patients with adult-onset diabetes produce and inhaled.some insulin, sometimes even large amounts.However, their bodies do not produce enough insulin aerotitis Middle ear problems due to changingor their body cells are resistant to the action of atmospheric pressures, as when a plane descendsinsulin. People with this form of diabetes are fre- to land. Symptoms include ear pain, ringing ears,quently overweight and can sometimes control their diminished hearing and, sometimes, dizziness. Alsodisease by losing weight through diet and exercise. known as aerotitis media, barotitis, barotitis media,Otherwise, they may need to combine insulin or and otic barotrauma.another diabetes medication with diet and exercise.See also diabetes, type 1. Aesculapius The ancient Roman god of medi- cine, whose staff with a snake curled around it isadult-onset Still’s disease Still’s disease that commonly used as a symbol of medicine. Accordingbegins in adulthood rather than in childhood. See to mythology, Aesculapius’s children includedalso Still’s disease. Hygeia, the goddess of health, and Panaceia, the goddess of healing.advance directive A document drawn up by apatient or, in some cases, the patient’s representa- affective disorder A psychiatric disorder thattive to set treatment preferences and to designate a affects the control of mood. See bipolar disorder;surrogate decision maker should the patient cyclothymia; depression; seasonal affective dis-become unable to make medical decisions. Advance order.
11 Aicardis syndromeafferent Carrying toward. A vein is an afferent ageusia An inability to taste sweet, sour, bitter, orvessel because it carries blood from the body salty substances. People who can taste sweet, sour,toward the heart. The opposite of afferent is effer- bitter, or salty substances but have a reduced abilityent. to do so are said to have hypogeusia.afferent nerve A nerve that carries impulses aggressive 1 In cancer medicine, quickly grow-toward the central nervous system. ing or tending to spread rapidly. For example, an aggressive tumor. 2 In psychiatry, having a ten-afferent vessel A vessel that carries blood dency to aggression or belligerent behavior.toward the heart. A vein or venule. aggressive fibromatosis See desmoid tumor.AFLP Acute fatty liver of pregnancy. agnosia An inability to recognize sensory inputsAFO Ankle-foot orthosis. such as light, sound, and touch). Agnosia is typically a result of brain injury. For example, damaging theAFP Alpha-fetoprotein. back part of the brain can cause visual agnosia (inability to properly recognize objects by sight).African tapeworm See Taenia saginata. agonist A substance that acts like another sub-African tick typhus See typhus, African tick. stance and therefore stimulates an action. Agonist is the opposite of antagonist. Antagonists and agonistsafterbirth The placenta and the fetal membranes are key players in the chemistry of the human bodythat are normally expelled from the uterus after the and in pharmacology.birth of a baby. See also placenta. agoraphobia An abnormal and persistent fear ofaftercare Medical care and instructions for public places or open areas, especially those frompatients after leaving a medical facility. which escape could be difficult or in which help might not be immediately accessible. Persons withagammaglobulinemia Total or near-totalabsence of infection-fighting antibodies belonging agoraphobia frequently also have panic disorder.to the class called gamma globulins. People with mild agoraphobia often live normalAgammaglobulinemia can be due to certain genetic lives by avoiding anxiety-provoking situations. In thediseases or caused by acquired diseases, including most severe agoraphobia, the victims may be inca-AIDS. pacitated and homebound. Agoraphobia tends to start in the mid to late 20s, and the onset mayagenesis Lack of development. For example, age- appear to be triggered by a traumatic event.nesis of a toe means the toe failed to form. agranulocytosis A marked decrease in the num-agenesis, sacral See caudal regression syn- ber of granulocytes (neutrophils). Agranulocytosisdrome. results in frequent chronic bacterial infections of the skin, lungs, throat, and other areas. It can be anagenesis of the gallbladder A condition in inherited genetic condition or acquired as, forwhich the gallbladder fails to develop. It occurs in 1 example, in leukemia. See also agranulocytosis,in about every 1,000 people, usually without addi- infantile genetic; granulocytopenia; severe con-tional birth defects. genital neutropenia.agent, antihypertensive See antihypertensive. agranulocytosis, infantile genetic An inherited condition characterized by a lack of granulocytesagent, anti-infective See anti-infective. (neutrophils), a type of white blood cell that is impor- tant in fighting infection, and a predisposition to fre-Agent Orange An herbicide and defoliant con- quent bacterial infections. Also known as Kostmanntaining 2,4-D and 2,4,5-T, as well as trace disease or syndrome and genetic infantile agranulocy-amounts of dioxin. Agent Orange was used as a tosis. See also agranulocytosis; granulocytopenia;defoliant in the Vietnam War. There has been con- severe congenital neutropenia.cern about Agent Orange potentially causing cancerand birth defects. agreement, arbitration See arbitration agree- ment.age-related macular degeneration See mac-ular degeneration. Aicardis syndrome A rare genetic disorder that occurs only in females and is caused by congenital
AID 12absence of the corpus callosum, a large bundle of longer breathing (apneic). Loss of consciousnessnerves that connects the left and right sides of the occurs if the obstruction is not relieved. Treatmentbrain. Features include epilepsy that emerges in of airway obstruction due to a foreign body includesinfancy and is difficult to control, vision problems due the Heimlich maneuver for adults, a series of fiveto maldeveloped retinas, developmental delay, and abdominal thrusts for children over 1 year of age,sometimes physical deformities of the spine, face, and a combination of five back blows with the flat ofand/or heart. See also epilepsy; seizure disorders. the hand and five abdominal thrusts with two fingers on the upper abdomen for infants.AID Artificial insemination by donor. AKA Above-the-knee amputation, generally per-AIDS Acquired immunodeficiency syndrome, a formed when the leg is not medically viable or tosyndrome caused by infection with the human prevent the spread of disease to the tissues aboveimmunodeficiency virus (HIV), with ensuing com- the knee from below.promise of the body’s immune system. Featuresinclude deficiency of certain types of leukocytes, akathisia A movement disorder characterized byespecially T cells; infection with opportunistic infec- a feeling of inner restlessness and a compellingtions that take advantage of the impaired immune need to be in constant motion, as well as by actionsresponse, such as tuberculosis, bacterial pneumo- such as rocking while standing or sitting, lifting thenia, human herpes virus, or toxoplasmosis; certain feet as if marching on the spot, and crossing andtypes of cancer, particularly Kaposi sarcoma; inabil- uncrossing the legs while sitting. People withity to maintain body weight (wasting); and in akathisia are unable to sit or keep still, complain ofadvanced cases, AIDS dementia complex. Treatment restlessness, fidget, rock from foot to foot, andfor AIDS has advanced rapidly. Antiviral, antibacter- pace.ial, and immune-boosting medications, among othertreatments, are part of current treatment protocols. akinesia The state of being without movement.AIDS dementia complex A brain disorder in akinetic Related to the loss of the normal abilitypeople with severe AIDS, causing loss of thinking to move the muscles.capacity and affecting the ability to function. AIDSdementia complex is considered an AIDS-defining akinetic epilepsy See epilepsy, akinetic.illness—that is, one of the serious illnesses thatoccurs in HIV-positive individuals warranting an akinetic mutism See mutism, akinetic.AIDS diagnosis, according to the definition of AIDSby the Centers for Disease Control and Prevention alanine aminotransferase An enzyme normally(CDC). present in liver, skeletal muscle, and heart cells. Abbreviated ALT. ALT is released into blood when theAIDS-related complex A term used in the early liver, skeletal muscle, or heart is inflamed oryears of the AIDS epidemic to describe people with injured by diseases, conditions, or medications.HIV infection who had only mild symptoms of illness, Also known as serum glutamic pyruvic transami-such as swollen lymph glands. It is rarely used today. nase (SGPT).Abbreviated ARC. albinism A pigmentation disorder characterizedairway The path that air follows to get into and by partial or total lack of the pigment melanin in theout of the lungs. The mouth and nose are the nor- skin, hair, and iris. Albinism is caused by an auto-mal entry and exit ports for the airway. Entering air somal recessive gene and can occur in people ofthen passes through the back of the throat (phar- any ethnic background. People with albinism haveynx) and continues through the voice box (larynx), delicate skin that sunburns and develops skin can-down the trachea, to finally pass through the cer easily, and they may suffer from eye disorders.bronchi. See also Hermansky-Pudlak syndrome; vitiligo.airway obstruction Partial or complete block- albino A person with albinism. The term was firstage of the breathing passages to the lungs. Causes applied by the Portuguese to people in West Africa,include the presence of foreign matter, allergic who may have had partial or complete albinism.reactions, infections, anatomical abnormalities, andtrauma. Associated respiratory distress may be sud- albuginea Tough white fibrous tissue. The tunicaden, with only a cough for a warning. There is often albuginea of the testis, for example, is the layer ofagitation in the early stages. Other signs include dense whitish inelastic tissue that surrounds thelabored, ineffective breathing, until the person is no testis.
13 allergic conjunctivitisalbumin The main protein in human blood and on the brain, liver, and other organs of the body,the key to regulating the osmotic pressure of blood. some of which can lead to death.Chemically, albumin is soluble in water, precipitatedby acid, and coagulated by heat. aldosterone A hormone produced by the outer portion (cortex) of the adrenal gland. Aldosteronealbuminuria More than the normal amount of regulates the balance of water and electrolytes in thealbumin in the urine. Albuminuria can be a sign that body, encouraging the kidney to excrete potassiumprotein is leaking through the kidney, most often into the urine and retain sodium, thereby retainingthrough the glomeruli, or a sign of significant kid- water. It is classified as a mineralocorticoid hor-ney disease. It may also be the harmless result of mone.vigorous exercise. Also known as proteinuria. aldosteronism See Conn syndrome.alcohol An organic substance formed when ahydroxyl group is substituted for a hydrogen atom in alexia Loss of the ability to read or understanda hydrocarbon. The type of alcohol used in alco- the written word, due either to brain damage thatholic beverages, ethanol, derives from fermenting disconnects these functions or to temporary dys-sugar with yeast. After alcohol is ingested, the body function caused by abnormal electrical or chemicalconverts it to sugar-based fuel. Alcohol acts as a activity in the brain.central nervous system depressant, and it may bepart of solutions used as preservatives, antiseptics, alienist French term for a psychologist, a psychi-or medications. atrist, or another practitioner who cares for the mentally ill.alcohol abuse Use of alcoholic beverages toexcess, either on individual occasions (binge drink- alimentary Concerning food, nourishment, anding) or as a regular practice. For some individu- the organs of digestion. From the Latin alimentum,als—children or pregnant women, for meaning nourishment.example—almost any amount of alcohol use maybe legally considered “alcohol abuse.” Heavy alco- alkaline phosphatase An enzyme that liberateshol abuse can cause physical damage and death. phosphate under alkaline conditions and is made in liver, bone, and other tissues. Alkaline phosphatasealcohol poisoning A condition in which a toxic can be measured in a routine blood test.amount of alcohol has been consumed, usually in a Abnormally high serum levels of alkaline phos-short period of time. The affected individual may phatase may indicate bone disease, liver disease, orbecome extremely disoriented, unresponsive, or bile duct obstruction.unconscious, with shallow breathing. Because alco-hol poisoning can be deadly, emergency treatment is alkalosis Relatively too much base in the bloodnecessary. and body, an abnormal condition resulting from the accumulation of base or the depletion of acid. Thealcohol use in pregnancy The consumption of pH of an alkalotic body measures above normal.alcohol during pregnancy, which can damage the The opposite of alkalosis is acidosis.fetus. See also fetal alcohol effect; fetal alcoholsyndrome. alkaptonuria A genetic metabolic disorder due to deficiency of the enzyme homogentisic acidAlcoholics Anonymous A free self-help organi- (HGA) dioxygenase. Deficiency of this enzyme leadszation founded to assist people addicted to alcohol to the three cardinal features of alkaptonuria (thein breaking old behavior patterns and gaining sup- presence of homogentisic acid in the urine),port for consistently living a sober lifestyle. ochronosis (bluish-black pigmentation in connec- tive tissue), and arthritis. Urine that turns dark is aalcoholism Physical dependence on alcohol to characteristic feature.the extent that stopping alcohol use would bring onwithdrawal symptoms. In popular and therapeutic allele An alternative form of a gene.parlance, the term may also be used to refer toingrained drinking habits that cause health or social allergen A substance that can cause an allergicproblems. Treatment requires first ending the phys- reaction. Common allergens include ragweedical dependence and then making lifestyle changes pollen, animal dander, and mold.that help the individual avoid relapse. In somecases, medication and hospitalization are necessary. allergic conjunctivitis Inflammation of theAlcohol dependence can have many serious effects whites of the eyes (conjunctivae), with itching, red- ness, and tearing, due to allergy.
allergic granulomatosis 14allergic granulomatosis See Churg-Strauss allergy skin test A test in which a small drop ofsyndrome. the suspected allergy-provoking substance (aller- gen) is placed on the skin and the skin is then gen-allergic reaction A hypersensitive immune tly scratched through the drop with a sterile needle.response to a substance. An allergic reaction can If the skin reddens and, more importantly, if itoccur when the immune system attacks a normally swells, the test is read as positive, and allergy to thatharmless substance. The allergic immune system substance is considered probable.calls upon a protective antibody calledimmunoglobulin E (IgE) to fight these invading sub- allergy to cockroaches An allergic reaction tostances. In the melee, cells called mast cells release tiny protein particles shed or excreted by cock-a variety of strong chemicals, including histamine, roaches. Asthma can be due to exposure to cock-into the tissues and blood. This chemical release is roach allergens. Removing cockroach allergensirritating and causes itching and swelling and can from the home is not an easy job, but it can go faralso lead to lung airway narrowing and throat tight- in reducing the frequency and severity of asthmaening, as is found in asthma, as well as to loss of and other allergic reactions.voice. For example, this is how hay fever and aller-gic pink eye (conjunctivitis) occur. See also allergic allograft The transplant of an organ or tissueconjunctivitis; allergic rhinitis; anaphylactic from one individual to another of the same speciesshock; asthma. with a different genotype. For example, a transplant from one person to another, but not an identicalallergic rhinitis Medical term for hay fever, an twin, is an allograft. Allografts account for manyallergic reaction that mimics a chronic cold. human transplants, including those from cadaveric,Symptoms include nasal congestion, a clear runny living related, and living unrelated donors. Alsonose, sneezing, nose and eye itching, and tearing of known as an allogeneic graft or a homograft.the eyes. Postnasal dripping of clear mucus frequentlycauses a cough, loss of smell is common, and occa- allopath A term sometimes applied to a physi-sionally loss of taste. Nosebleeds may occur. Also cian who practices allopathy, or conventional medi-known as June cold and summer cold. cine. See also allopathy.allergic rhinitis, perennial Allergic rhinitis allopathic medicine See allopathy.that occurs throughout the year. allopathy The system of medical practice thatallergic rhinitis, seasonal Allergic rhinitis that treats disease by the use of remedies to produceoccurs during a specific season. effects different from those produced by the disease under treatment. Doctors of medicine (MDs) prac-allergic salute The characteristic gesture of a tice allopathic medicine. The term “allopathy” wasperson with allergic rhinitis: rubbing his or her coined to designate conventional medicine asnose with the index finger. opposed to homeopathy, the system of therapy based on the concept that disease can be treatedallergic vasculitis See Churg-Strauss syn- with drugs (in minute doses) thought capable ofdrome. producing the same symptoms in healthy people as the disease itself. Allopathy is also known as con-allergy Hypersensitivity of the body’s immune ventional medicine. See also allopath.system in response to exposure to specific sub-stances (antigens), such as pollen, bee stings, poi- alopecia Baldness. Temporary alopecia mayson ivy, drugs, or foods. See also allergic reaction; occur as a result of chemotherapy. Permanentanaphylactic shock. alopecia may result from any of several conditions, including common male-pattern baldness.allergy desensitization Stimulation of the Radiation therapy administered to the head can alsoimmune system with gradually increasing doses of cause permanent alopecia due to irreversible dam-the substances to which a person is allergic in order age to the hair follicles. See also alopecia areata;to modify or stop the allergic response. This form of alopecia capitis totalis; alopecia universalis;treatment is very effective for allergies to pollen, alopecia, traumatic.mites, animal dander, and stinging insects, includ-ing bees, hornets, yellow jackets, wasps, velvet ants, alopecia, traumatic Hair loss caused by injuryfire ants, and certain necessary medications. to the scalp. Common causes include the use of caustic hair straighteners, especially those thatallergy scratch test See allergy skin test. include lye as an ingredient; stress traction injury
15 altitude illnessfrom tight rollers and braiding; overheating of the apparent at a very early age or anytime later, mani-hair shafts; and compulsive pulling out of hair (tri- festing as shortness of breath due to emphysema orchotillomania). as liver symptoms such as jaundice, fatigue, fluid in the abdomen, mental changes, or gastrointestinalalopecia areata Patchy baldness that typically bleeding. Treatment options include, for lung dis-begins with rapid hair loss on discrete areas of the ease, replacement of the missing alpha-1 antit-scalp and sometimes progresses to complete bald- rypsin. Avoidance of smoking and of other lungness and even loss of body hair. The characteristic irritants is an important part of management.diagnostic finding is short, broken hairs called Treatment of the liver disease is liver transplant.“exclamation point” hairs. Alopecia areata affects Also known as protease inhibitor 1 deficiency.both males and females and, most often, childrenand young adults. It seems to be caused by an alpha-fetoprotein A plasma protein normallyautoimmune mechanism, wherein the body’s own produced by a fetus, principally in the fetus’s liver,immune system attacks the hair follicles and dis- the fetal gastrointestinal tract, and the yolk sac, arupts normal hair formation. Alopecia areata is structure temporarily present during embryonicsometimes associated with allergic disorders, thy- development. Abbreviated AFP. The level of AFP isroid disease, vitiligo, lupus, rheumatoid arthritis, typically high in the fetus’s blood. It goes down afterulcerative colitis, and other conditions, and some birth. By 1 year of age, it is virtually undetectable.forms may be inherited. Hair can sometimes regrow During pregnancy, AFP crosses the placenta fromwithin a year without treatment. The longer the the fetal circulation and appears in the mother’speriod of time of hair loss, the less chance that the blood. The level of AFP in the mother’s blood pro-hair will regrow. vides an opportunity to screen for a number of dis- orders, including open neural tube defects (such asalopecia capitis totalis Loss of all scalp hair, anencephaly and spina bifida), Down syndrome,with normal hair elsewhere on the body remaining. and other chromosome abnormalities.alopecia universalis Loss of all hair on the Alport syndrome A hereditary condition charac-entire body. terized by kidney disease, deafness, and sometimes eye defects. Alport syndrome involves inflammationalpha cell, pancreatic A type of cell found in of the kidney (nephritis), often progressing to kid-areas within the pancreas called the islets of ney failure, and sensory nerve hearing loss.Langerhans. Alpha cells make and release glucagon, Progression to kidney failure is gradual and usuallywhich raises the level of glucose (sugar) in the occurs in males before 50 years of age.blood. ALS Amyotropic lateral sclerosis, Lou Gehrig’salpha error The statistical error made in testing a disease.hypothesis when it is concluded that a result is posi-tive, but it really is not. Also known as false positive. ALT Alanine aminotransferase.alpha interferon One of the three main classes alternative medicine Healing arts not taught inof interferons, which are specialized proteins (lym- traditional Western medical schools that promotephokines) produced by the body in response to options to conventional medicine that is taught inmicrobial infection that interfere with the multipli- these schools. An example of an alternative therapycation of viruses in cells. The other two main classes is using a special diet to treat cancer instead ofare called beta interferon and gamma interferon. undergoing surgery, radiation, or chemotherapySee also interferon; interferon therapy. that has been recommended by a Western physi- cian. Complementary medicine is different fromAlpha Omega Alpha An honor society, the med- alternative medicine. Whereas complementary med-ical school equivalent of Phi Beta Kappa of under- icine is used together with conventional medicine,graduate school. alternative medicine is used in place of conventional medicine. See also complementary medicine;alpha thalassemia See thalassemia, alpha. conventional medicine.alpha-1 antitrypsin deficiency An inherited altitude, acclimatization to See acclimatiza-disorder characterized by a lack of the alpha-1 tion to altitude.antitrypsin protease inhibitor. Alpha-1 antitrypsindeficiency leads to damage of various organs, espe- altitude illness See altitude sickness.cially the lung and liver. Symptoms may become
altitude sickness 16altitude sickness Sickness caused by being at a Bilateral amastia (absence of both breasts) is asso-high altitude, usually above 2,400 meters ciated with multiple birth defects involving other(approximately 8,000 feet). The cause of altitude parts of the body. See also amazia.sickness is a matter of oxygen physiology. At sealevel the concentration of oxygen is about 21 per- amaurosis fugax A symptom that is oftencent, and the barometric pressure averages 760 mm described as a shade coming down over the eye.Hg. As altitude increases, the concentration remains Amaurosis fugax is a partial or complete loss ofthe same, but the number of oxygen molecules per sight that is temporary. Amaurosis fugax is usuallybreath is reduced. At 5,400 meters (approximately caused by arteriosclerosis in the blood vessels that12,000 feet) above sea level, the barometric pres- supply the brain. It can also occur with excessivesure is only 483 mm Hg, so there are roughly 40 acceleration, as in flight, and with ophthalmicpercent fewer oxygen molecules per breath. In migraine. See also arteriosclerosis.order to oxygenate the body effectively, the breath-ing rate must increase. This extra ventilation amaurotic familial idiocy An outdated term forincreases the oxygen content in the blood—but not Tay-Sachs disease (TSD). See Tay-Sachs disease.to sea level concentrations. Because the amount ofoxygen required for activity is the same at high alti- amazia A condition wherein the breast tissue istude as at sea level, the body must adjust to having absent, but the nipple is present. Amazia is typicallyless oxygen. In addition, high altitude and lower air a result of radiation or surgery.pressure cause fluid to leak from the capillaries,which can cause fluid buildup in the lungs and the ambidextrous Able to use both the right and leftbrain. Prevention measures for altitude sickness hands with equal dexterity. Neither right- nor left-include avoiding or retreating from high-altitude handed.areas, gradual acclimatization, and medication. The amblyopia, nocturnal Night blindness, alsoacclimatization process is inhibited by dehydration, known as day sight. See nyctanopia.overexertion, and intake of alcohol and depressantdrugs. Preventive medications include acetazo- ambulance A vehicle equipped with medicationslamide (brand name: Diamox) and dexamethasone and devices intended to stabilize patients while(a steroid). See also acclimatization to altitude; speeding them to a hospital. In its original sense, anacute mountain sickness. ambulance was a mobile field hospital.alveolitis Inflammation of the alveoli, the air sacs ambulatory Able to walk about, not bedriddenin the lungs. or immobile.alveolus A tiny air sac in the lungs. Plural alveoli. ambulatory care Medical care provided on an outpatient basis, including diagnosis, observation,Alzheimer’s disease A progressive degenerative treatment, and rehabilitation services.disease of the brain that leads to dementia. On a cel-lular level, Alzheimer’s disease is characterized by ameba A single-celled, protozoan organism thatthe finding of unusual helical protein filaments in constantly changes shape. Amebae can infect thenerve cells of the brain. These twisted filaments are bowels, causing diarrhea. They can also infect thecalled neurofibrillary tangles. In the brain, liver, causing abscesses to form.Alzheimer’s disease involves degeneration of thecortical regions, especially the frontal and temporal amebiasis The state of being infected with ame-lobes. There is currently no cure for Alzheimer’s bae, especially with the ameba Entamoeba histolytica.disease, but new medications and therapies appearto slow its progress and improve the patient’s ability amebic colitis Amebic dysentery with ulcers into function. the colon from infection with the ameba Entamoeba histolytica. This single-celled parasite is transmittedAMA American Medical Association, a profes- to humans via contaminated water and food.sional organization for physicians that sets widelyaccepted standards of practice and ethics and that amebic dysentery Inflammation of the intestinepublishes the weekly journal JAMA ( Journal of the due to infection with the ameba Entamoeba histolyt-American Medical Association). ica. Amebic dysentery can be accompanied by ame- bic infection of the liver and other organs.amastia A rare condition wherein the normalgrowth of the breast or nipple does not occur. amelanotic Without melanin. A skin lesion that isUnilateral amastia (absence of one breast) is often amelanotic lacks the pigment melanin and, there-associated with absence of the pectoral muscles. fore, is essentially colorless.
17 amputationamelanotic melanoma See melanoma, ame- are normally found primarily in cells in the liver andlanotic. heart.amelioration Improvement in a patient’s condi- amitriptyline A tricyclic antidepressant drugtion, or the activity of making an effort to correct, or (brand name: Elavil) prescribed to treat depres-at least make more acceptable, conditions that are sion, chronic pain, migraines, eating disorders, anddifficult to endure related to patient’s conditions. a wide variety of other conditions. See also tricyclic antidepressant.amenorrhea See menstruation, cessation of. AML See leukemia, acute myeloid.amenorrhea, physiologic The cessation ofmenstruation for completely normal reasons. The amnesia An impairment to or lack of memory.lack of menstruation during pregnancy and lacta- Antegrade amnesia refers to a lack of memory oftion are forms of physiologic amenorrhea. events occurring after a traumatic event, whereas retrograde amnesia refers to lack of memory ofamenorrhea, primary The failure of menstrua- events that occurred before the event.tion to occur at puberty. amniocentesis A before-birth diagnostic proce-amenorrhea, secondary The cessation of men- dure during which a long needle is used to obtainstruation for abnormal reasons. Causes include amniotic fluid from within the uterus. This fluid cananorexia nervosa, disease of the female reproduc- be used for genetic and other diagnostic tests.tive tract, and overexercise. Secondary amenorrhea Informally known as amnio.can also be caused by certain medications, notablythe birth control medication medroxyprogesterone amnion A thin membrane that surrounds the(brand name: Depo-Provera); in this case, amenor- fetus during pregnancy. The amnion is the inner ofrhea is an expected effect. the two fetal membranes (the chorion is the outer one), and it contains the amniotic fluid.American Type Culture Collection The world’spremier biological culture repository, and a key amniotic fluid The fluid bathing a fetus withinresource for medical research. the uterus, which serves as a shock absorber.AMI Acute myocardial infarction. amphetamine A drug that has a stimulant effect on the central nervous system that can be both phys-amine A chemical compound containing nitro- ically and psychologically addictive when overused.gen. Amines are derived from ammonia. Amphetamine has been much abused recreationally. The street term “speed” refers to stimulant drugsamino acid One of the 20 building blocks from such as amphetamine.which proteins are assembled. Isoleucine, leucine,lysine, phenylalanine, threonine, tryptophan, and amplification An event that produces multiplevaline are deemed “essential” amino acids because copies of a gene or of any sequence of DNA. Genethe human body cannot make them and they must amplification plays a role in cancer. Amplificationbe obtained in the diet. Amino acids are sometimes can occur in vivo (in the living individual) or intaken orally in supplement form. vitro (in the laboratory).amino acid screen A screening blood or urine ampulla of Vater A small projection into thetest that returns information about the levels of duodenum through which bile and pancreaticamino acids. An amino acid screen is useful in diag- secretions flow to mix with food for digestion.nosing certain conditions, including the inbornerrors of amino acid metabolisms such as amputation Removal of part or all of a body partphenylketonuria (PKU). that is enclosed by skin. Amputation can occur at an accident site, the scene of an animal attack, or a bat-aminotransferase An enzyme that catalyzes the tlefield. Amputation is also performed as a surgicaltransfer of an amino group from a donor molecule procedure. It is typically performed to prevent theto a recipient molecule. The donor molecule is usu- spread of gangrene as a complication of frostbite,ally an amino acid and the recipient molecule is injury, diabetes, arteriosclerosis, or any other ill-usually an alpha-2 keto acid. Two of the best-known ness that impairs blood circulation. It is also per-enzymes in this class are serum glutamic formed to prevent the spread of bone cancer and tooxaloacetic transaminase (SGOT) and serum glu- curtail loss of blood and infection in a person whotamic pyruvic transaminase (SGPT), both of which has suffered severe, irreparable damage to a limb.
AMS 18When performing an amputation, surgeons gener- percent of the normal population, usually in lowally cut above the diseased or injured area so that a titers (low levels).portion of healthy tissue remains to cushion bone.Sometimes the location of a cut may depend in part anaerobic Not requiring oxygen. Anaerobic bac-on its suitability to be fitted with an artificial limb, or teria, for example, do not require oxygen to grow.prosthesis. anal fissure A tear in the anal canal, one of theAMS 1 Atypical measles syndrome. 2 Acute most common causes of red blood in the stool.mountain sickness. anal itching Irritation of the skin at the exit ofamygdala 1 The amygdaloid nucleus in the the rectum, accompanied by the desire to scratch.brain. 2 The tonsils. These structures were so The intensity of anal itching is increased by mois-named because they appeared to be shaped like an ture, pressure, and abrasion caused by clothing andalmond. sitting. It may be caused by irritating chemicals in food (as in spices, hot sauces, and peppers); irrita-amyloidosis A group of diseases that result from tion due to frequent liquid stools, as in diarrhea;the abnormal deposition of a protein, called amy- diseases, such as diabetes mellitus or HIV infection,loid, in various tissues of the body. Amyloid protein that increase the possibility of yeast infections; andcan be deposited in a localized area, and it may not psoriasis. Other causes of anal itching include hem-be harmful or it may affect only a single tissue of the orrhoids, anal fissures, abnormal local growth ofbody. This form of amyloidosis is called localized anal skin (anal papillae), and skin tags. Treatmentamyloidosis. Amyloidosis that affects tissues is directed first toward relieving the burning andthroughout the body is referred to as systemic amy- soreness, including cleaning and drying the anusloidosis. Systemic amyloidosis can cause serious thoroughly, avoiding leaving soap in the anal area,changes in organs throughout the body. Amyloidosis showering gently without directly rubbing or irritat-can occur as its own entity or secondarily, as a ing the skin, and using moist pads rather than toiletresult of another illness, including multiple paper to clean the anus after bowel movements.myeloma, chronic infections (such as tuberculosis Local application of cortisone cream may help. Alsoor osteomyelitis), or chronic inflammatory diseases known as pruritus ani.(such as rheumatoid arthritis and ankylosingspondylitis). analgesia The inability to feel pain.amyotrophic lateral sclerosis A progressive analgesic A drug that relieves pain.chronic disease of nerves from the spinal cord thatare responsible for supplying electrical stimulation analysis In psychology, a term for conversation-to the muscles. Abbreviated ALS. ALS is progressive based therapeutic processes used to gain under-and usually fatal in less than eight years, from ill- standing of complex emotional or behavioral issues.nesses that strike as the body becomes weaker. ALSoccurs most often in adults over 50. The cause of anaphylactic shock A widespread and extremelyALS is unknown. It is sometimes called Lou Gehrig’s serious allergic reaction that can result in death.disease, after a great baseball player who was its Symptoms include dizziness, loss of consciousness,best-known victim. labored breathing, swelling of the tongue and breathing tubes, blueness of the skin, low bloodANA Antinuclear antibody , detected when a blood pressure, and heart failure. Immediate emergencysample is microscopically evaluated using special treatment is required, for example, administrationcellular stain methods. ANAs indicate autoimmu- of epinephrine in the case of bee or wasp stings. Seenity, or, an overactive misdirected immune system also allergic reaction.that can be asssociated with inflammation of varioustissues of the body. The ANA test reveals different anaphylactoid purpura A form of blood vesselpatterns, depending on how the cell nucleus is inflammation that affects small capillaries in thestained in the laboratory: homogeneous, or diffuse; skin and the kidneys. It results in skin rash associ-speckled; nucleolar; and peripheral, or rim. ated with joint inflammation (arthritis) and cramp-Although these patterns are not specific for any one ing pain in the abdomen. Anaphylactoid purpuraillness, certain illnesses can more frequently be frequently follows a bacterial or viral infection of theassociated with some patterns. For example, the throat or breathing passages, and it is an unusualnucleolar pattern is commonly found in the disease reaction of the body’s immune system to this infec-scleroderma. The speckled pattern is seen in many tion. It occurs most commonly in children.conditions and in persons who have no autoim- Generally a mild illness that resolves spontaneously,mune disorder. ANAs are found in approximately 5 anaphylactoid purpura can sometimes cause serious
19 anemia, Mediterraneanproblems in the kidneys and bowels. Treatment is androsterone A male sex hormone that is founddirected toward the most significant area of involve- in the blood and urine of men and women. It isment. Also known as Henoch-Schonlein purpura seven times weaker than testosterone.(HSP). anemia The condition of having a lower-than-anaphylaxis An allergic reaction. In severe normal number of red blood cells or quantity ofcases, anaphylaxis can include potentially deadly hemoglobin. Anemia diminishes the capacity of theanaphylactic shock. See also allergic reaction; blood to carry oxygen. Patients with anemia may feelanaphylactic shock. tired, fatigue easily, appear pale, develop palpita- tions, and become short of breath. Children withanastomosis The connection of normally sepa- chronic anemia are prone to infections and learningrate parts. An anastomosis may be naturally occur- problems. The main causes of anemia are bleeding,ring or it may be created during embryonic hemolysis (excessive destruction of red blooddevelopment, surgery, or trauma, or by pathological cells), underproduction of red blood cells (as inmeans. An anastomosis may, for example, connect bone marrow diseases), and underproduction oftwo blood vessels, or it may connect the healthy sec- normal hemoglobin (as in sickle cell anemia and intions of the colon or rectum after a cancerous or iron deficiency anemia). Women are more likelyotherwise diseased portion has been surgically than men to have anemia because of menstrualremoved. blood loss. In children, anemia is most commonly due to insufficient iron in the diet. Anemia is alsoanat. Abbreviation for anatomy. often due to gastrointestinal bleeding caused by medications, including such common drugs asanatomy The study of human or animal form, by aspirin and ibuprofen.observation or examination of the living being,examination or dissection of dead specimens, anemia, Addisonian See anemia, pernicious.microscopic examination, and/or textbooks. anemia, aplastic Anemia due to failure of theanatomy, gross In medicine, the study of human bone marrow to produce red and white blood cellsstructures that can be seen with the naked eye. as well as platelets. Aplastic anemia frequentlyKnown among medical students studying human occurs without a known cause. Known causesanatomy simply as “gross.” include exposure to chemicals (for example, ben- zene, toluene in glues, insecticides, solvents), drugsanatomy, microscopic The study of normal (for example, chemotherapy drugs, gold, seizurestructure of an organism under the microscope. medications, antibiotics), viruses (for instance, HIV,Known among medical students simply as “micro.” Epstein-Barr), radiation, immune conditions (forAlso known as histology. example, systemic lupus erythematosus, rheumatoid arthritis), pregnancy, paroxysmal nocturnal hemo-anatripsis The use of friction as a treatment globinuria, and inherited disorders (for example,modality for a medical condition. Anatripsis may or Fanconi anemia).may not also involve the application of a medicament. anemia, Cooley See thalassemia.Anderson-Fabry disease See Fabry disease. anemia, Fanconi See Fanconi anemia.androgen A group of hormones, includingandrosterone, that promotes the development and anemia, iron deficiency Anemia due to inade-maintenance of male sex characteristics. Androgen quate iron. Iron is necessary to make hemoglobin,production is stimulated by the hormone testos- the molecule in red blood cells that is responsibleterone. See also testosterone. for the transport of oxygen. In iron deficiency ane- mia, the red cells are small and pale. Characteristicandroid pelvis See male pelvis. features of iron deficiency anemia in children include failure to thrive and increased infections.androstenedione A steroid produced in theadrenal gland that is a precursor to testosterone and Iron deficiency anemia can be treated with iron sup-other male hormones (androgens). Known popu- plements and iron-containing foods. Food sourceslarly as andro, it has been used as a supplement to of iron include meat, poultry, eggs, vegetables, and certain cereals. Iron supplements may also beincrease muscle strength. Taking andro raises taken, although they should never be given to chil-testosterone levels above normal. Side effects dren without a physician’s recommendation.include acne, male baldness, and a decrease in“good” cholesterol (which may predispose to heart anemia, Mediterranean See thalassemia.disease and stroke).
anemia, pernicious 20anemia, pernicious Low red blood cell count anesthetic A substance that causes lack of feelingcaused by inadequate vitamin B12. Abbreviated PA. or awareness, dulling pain to permit surgery andPatients with PA do not produce intrinsic factor other painful procedures.(IF), a substance that allows the body to absorbvitamin B12 from foods. The resulting inadequacy anesthetic, epidural An anesthetic injected intoof vitamin B12 hampers the production of red blood the epidural space surrounding the fluid-filled saccells. PA can be treated by injection of vitamin B12: (the dura) around the spinal cord. It partiallyoral administration will not work because people numbs the abdomen and legs and is most com-with PA cannot absorb orally administered vitamin monly used during childbirth.B12. Also known as Addison’s anemia. anesthetic, general An anesthetic that puts aanemia, refractory Anemia that is unresponsive person to sleep rendering them unconscious.to treatment. anesthetic, local An anesthetic that causes lossanemia, sickle cell A genetic blood disorder of feeling in a limited part of the body.caused by the presence of an abnormal, sickle-shaped form of hemoglobin. These hemoglobin anesthetist A nurse or technician trained tomolecules tend to aggregate after unloading oxygen, administer anesthetics.forming long, rod-like structures that force the redcells to assume a sickle shape. Unlike normal red aneuploidy A condition in which a person hascells, which are usually smooth and malleable, the one or a few chromosomes above or below the nor-sickle red cells cannot squeeze through small blood mal chromosome number. For example, threevessels. When the sickle cells block small blood ves- copies of chromosome 21, which is characteristicsels, the organs are deprived of blood and oxygen. of Down syndrome, is a form of aneuploidy.This leads to periodic episodes of pain and damagesthe vital organs. Sickle red cells die after only about aneurysm A localized widening (dilatation) of an10 to 20 days, instead of the usual 120 days or so. artery, a vein, or the heart. At the point of anBecause they cannot be replaced fast enough, the aneurysm, there is typically a bulge. The wall of theblood is chronically short of red cells, causing ane- blood vessel or organ is weakened and may rupture.mia. The gene for sickle cell anemia must be inher- aneurysm, abdominal aortic A balloon-likeited from both parents for the illness to occur in swelling in the wall of the aorta within the abdomen.children. A child with only one copy of the gene may This swelling weakens the aorta’s wall and, becausehave sickle-cell traits but no symptoms of illness. of the great volume of blood flowing under highSee also sickle cell trait. pressure in the aorta, it can rupture. An abdominalanencephaly Absence of the cranial vault and of aortic aneurysm is monitored by ultrasound.most or all of the cerebral hemispheres of the brain, Surgery is often recommended if the aneurysm isa lethal malformation. Anencephaly is due to imper- more than 5.5 centimeters (2.2 inches) in diameterfect development of the neural tube, the structure or if a smaller aneurysm is enlarging with unusualthat gives rise to the central nervous system, during rapidity.very early pregnancy. The upper end of the neuraltube fails to close. The risk of all neural tube aneurysm, aortic An aneurysm of the largest artery in the body, the aorta, involving that vessel indefects, including anencephaly, is decreased if the its course above the diaphragm (thoracic aorticmother’s diet during pregnancy contains ample folic aneurysm) or, more commonly, below theacid. See also neural tube defect. diaphragm (abdominal aortic aneurysm). Becauseanesthesia Loss of feeling or awareness, as when of the volume of blood flowing under relatively highan anesthetic is administered before surgery. pressure within the aorta, a ruptured aneurysm of the aorta is a catastrophe. See also aneurysm,anesthesiologist A physician or, less often, a abdominal aortic; aneurysm, thoracic.dentist who is specialized in the practice of anesthe-siology. aneurysm, arterial An aneurysm involving an artery.anesthesiology The branch of medicine special-izing in the use of drugs or other agents that cause aneurysm, arteriosclerotic An aneurysm thatinsensibility to pain. occurs because a vessel wall is weakened by arte- riosclerosis. Also known as atherosclerotic aneurysm. See also arteriosclerosis.
21 angioid streaksaneurysm, berry A small aneurysm that looks angina Chest pain due to an inadequate supply oflike a berry and classically occurs at the point at oxygen to the heart muscle. The pain is typicallywhich a cerebral artery departs from the circular severe and crushing, and it is characterized by aartery (the circle of Willis) at the base of the brain. feeling of pressure and suffocation just behind theBerry aneurysms frequently rupture and bleed. breastbone. Angina can accompany or be a precur- sor of a heart attack.aneurysm, brain An aneurysm of a blood vesselin the brain, usually due to a defect in the vessel at angina, Prinzmetal Chest pain due to a coro-birth or from high blood pressure. Rupture of the nary artery spasm, a sudden constriction of one ofaneurysm causes a sudden severe headache, often the vessels that supply the heart muscle with bloodwith nausea, vomiting, decreased consciousness, that is rich in oxygen. This spasm deprives the heartand can be life threatening. muscle of blood and oxygen. Treatments include beta-blocker medications and nitroglycerin to openaneurysm, cardiac An outpouching of an abnor- up the coronary arteries. Also known as variantmally thin portion of the heart wall. Cardiac angina. See also coronary artery spasm.aneurysms tend to involve the left ventricle becausethe blood there is under the greatest pressure. angina, variant See angina, Prinzmetal.aneurysm, dissecting An aneurysm in which the angina, Vincent See acute membranous gin-wall of an artery rips (dissects) longitudinally. This givitis.occurs because bleeding into the weakened wallsplits the wall. Dissecting aneurysms tend to affect angina pectoris See angina.the thoracic aorta. They are a particular danger inMarfan syndrome. angioedema A skin condition that resembles hives but affects a deeper skin layer causing local-aneurysm, fusiform An aneurysm that is shaped ized swellings of soft tissues, such as the tongue orlike a spindle and widens an artery or a vein. lips. Angioedema can be a sign of an allergic reac- tion. See also angioedema, hereditary.aneurysm, miliary A tiny, millet-seed–sizedaneurysm that tends to affect minute arteries in the angioedema, hereditary A genetic form ofbrain and, in the eye, the retina. angioedema. Persons with it are born lacking the enzyme C1 esterase inhibitor, a protein that nor-aneurysm, saccular An aneurysm that resembles mally inhibits the activation of a cascade of proteins.a small sack. A berry aneurysm is typically saccular. Without this inhibitor protein, angioedema occurs, resulting in recurrent attacks of swollen tissues,aneurysm, thoracic An aneurysm of the largest pain in the abdomen, and swelling of the voice boxartery in the body, the aorta, involving that vessel in (larynx), which can compromise breathing. Theits course within the thorax (chest). Because of the diagnosis of hereditary angioedema is confirmed byvolume of blood flowing under relatively high pres- finding subnormal blood levels of C1 esterasesure within the aorta, a ruptured aneurysm of the inhibitor. Treatment and prevention options includeaorta is a catastrophe. See also aneurysm, abdom- antihistamines and male steroids (androgens). Alsoinal aortic; aneurysm, aortic. known as hereditary angioneurotic edema. See also angioedema.aneurysm, venous A localized widening of avein. angiogenesis The process of developing new blood vessels. Angiogenesis is critically importantaneurysmal bone cyst See bone cyst, aneurys- during the normal development of the embryo andmal. fetus. It also appears to be important during tumor formation.anger An emotional state that may range in inten-sity from mild irritation to intense fury and rage. angiogram An X-ray image of blood vessels. TheAnger has physical effects, including raising the vessels can be seen because a contrast dye withinheart rate and blood pressure, as well as the levels them blocks the X-rays from developing an imagingof adrenaline. film.angiitis Inflammation of the walls of small blood angioid streaks Tiny breaks in the elastin-filledvessels. Also known as vasculitis. tissue in the retina in the back of the eye. Angioid streaks are seen in patients with pseudoxanthomaangiitis, allergic granulomatous See Churg- elasticum, a rare disorder of degeneration of theStrauss syndrome. elastic fibers with tiny areas of calcification in the
angiokeratoma corporis diffusum universale 22skin, retinae, and blood vessels, and they are visible the eye. This causes the pressure in the eye to soar,during an examination using an ophthalmoscope. which can damage the optic nerve and lead to blind-Angioid streaks can cause blindness. ness. The elevated pressure is ideally to be detected before the appearance of other symptoms of angle-angiokeratoma corporis diffusum universale closure glaucoma, so the pressure is routinelySee Fabry disease. checked during eye exams. Symptoms of acute angle-closure glaucoma include severe eye andangioneurotic edema, hereditary See facial pain, nausea and vomiting, blurred vision,angioedema, hereditary. and a halo effect around lights. Acute angle-closure glaucoma is an emergency because optic nerveangiopathy Disease of the arteries, veins, and damage and vision loss can occur within hours of itscapillaries. There are two types of angiopathy: onset. Angle-closure glaucoma tends to affect peo-microangiopathy and macroangiopathy. In microan- ple born with a narrow angle between the corneagiopathy, the walls of small blood vessels become so and iris. See also glaucoma.thick and weak that they bleed, leak protein, andslow the flow of blood. For example, diabetics may anhidrosis Lack of sweating. Anhidrosis createsdevelop microangiopathy with thickening of capil- a dangerous inability to tolerate heat.laries in many areas, including the eye. In macroan-giopathy, fat and blood clots build up in the large anisocoria A condition in which the left and rightblood vessels, stick to the vessel walls, and block pupils of the eyes are not of equal size. The size ofthe flow of blood. Macroangiopathy in the heart is the pupil determines how much light is let into thecoronary artery disease; in the brain, it is cere- eye. With anisocoria, the larger pupil lets more lightbrovascular disease. Peripheral vascular disease is enter the eye. There are many causes of anisocoria,macroangiopathy that affects, for example, vessels including eye injury or infection and swelling withinin the legs. the brain.angioplasty A procedure in which a balloon- anisocytosis Excessive inequality in the size oftipped catheter is used to enlarge a narrowing in a the red blood cells. Anisocytosis is apparent on acoronary artery caused by arteriosclerosis. Also blood smear examined under a microscope.known as percutaneous transluminal coronaryangioplasty (PTCA). See also arteriosclerosis. ankle A complex structure made up of two joints: the true ankle joint and the subtalar joint. Theangiosarcoma A form of tissue cancer (sar- ankle’s movement is constrained and controlled bycoma) that arises in the lining of blood vessels. ligaments, including the anterior tibiofibular liga-Angiosarcomas tend to be aggressive, recur locally, ment, which connects the tibia to the fibula; the lat-and spread widely. Predisposing factors include eral collateral ligaments, which attach the fibula tolymphedema (as from a radical mastectomy), the calcaneus to give the outside of the ankle stabil-radiotherapy, foreign materials (such as steel and ity; and the deltoid ligaments on the inside of theplastic) in the body, and environmental agents ankle, which connect the tibia to the talus and cal-(such as arsenic solutions used to spray grapevines caneus to provide medial stability to the ankle. Seeand vinyl chloride in the plastic industry). also ankle joint.angiostatin A fragment of a protein, plasmino- ankle joint A joint that is composed of threegen, that is involved in blood clotting. Angiostatin is bones: the tibia, the fibula, and the talus. The anklenormally secreted by tumors, and it appears to halt joint is responsible for the up-and-down motion ofthe process of developing new blood vessels, which the foot. The subtalar joint is under the ankle joint,is necessary to tumor development. and it consists of the talus on top and calcaneus on the bottom. The subtalar joint is responsible for theangiotensin A family of peptides that constrict side-to-side motion of the foot.blood vessels. Narrowing the diameter of the bloodvessels causes blood pressure to rise. ankle-foot orthosis A brace, usually made of plastic, that is worn on the lower leg and foot toangiotensin converting enzyme See ACE. support the ankle, hold the foot and ankle in the correct position and correct foot drop. Abbreviatedangle-closure glaucoma Increased pressure in AFO. Also known as foot drop brace.the front chamber of the eye due to blockage of itsnormal circulation of fluid. When the iris retracts ankyloglossia A minor birth defect in which theand thickens (when the pupil of the eye is wide flap of membrane attached to the underside of theopen), it blocks the drainage pathway for fluid in tongue (frenulum) is too short. This shortened
23 anterior cruciate ligamentfrenulum limits the mobility of the tongue. anorexia nervosa An eating disorder character-Ankyloglossia is also called tongue tie, from the folk ized by extreme attempts to control the diet and/orbelief that the anomaly causes feeding and speech an aversion to food. It affects young women mostproblems. A child cannot feed or speak properly often, but it may also be seen in men, children, andbecause the tongue is “tied.” This antiquated belief older adults. Symptoms can include extreme weightis untrue. loss, weakness, and dulling of hair and skin. In some cases, anorexia nervosa may be a form ofankylosing Having a tendency to stiffen and fuse obsessive-compulsive disorder. Treatment includestogether. medication, therapy, dietary counseling and, in extreme cases, hospitalization. Untreated anorexiaankylosing spondylitis A form of chronic can cause organ failure and death. See also bodyinflammation of the spine and the sacroiliac joints. dysmorphic disorder; bulimia nervosa; obsessive-Chronic inflammation in these areas causes pain compulsive disorder.and stiffness in and around the spine. Over time,chronic spinal inflammation (spondylitis) can lead anorexic 1 Pertaining to, or having the appear-to a complete cementing together (fusion) of the ance of, anorexia. 2 Lack of appetite. 3 A drugvertebrae, a process called ankylosis. Ankylosing or other agent that causes anorexia and so dimin-spondylitis can sometimes be seen in patients with ishes the appetite. See also anorexia.psoriasis and inflammatory bowel disease (ulcera-tive and Crohn’s colitis). anorexigenic Causing anorexia (loss of appetite) as, for example, an anorexigenic drug. Seeankyrin deficiency A genetic disorder of the red also anorexia.blood cell membrane. Ankyrin deficiency is thecause of hereditary spherocytosis. See also sphero- anorgasmia Failure to achieve orgasm (climax)cytosis, hereditary. during sexual intercourse. Anorgasmia has many causes, including stress, anxiety, depression,anlage 1 In biology, whatever precedes some- fatigue, worry, guilt, fear of painful intercourse, fearthing else. 2 In embryology, a precursor or fore- of pregnancy, the undesirability of a partner, therunner, of a more mature structure or organ. 3 In undesirability of a setting, and the use of alcohol orpsychoanalysis, a predisposition to a given trait or prescription or illicit drugs.personality characteristic. anosmia The failure of the development of or theANLL Acute nonlymphocytic leukemia. loss of the sense of smell.annexin One of a family of proteins that bind cal- anotia The absence from birth of the external,cium and phospholipids. visible part of the ear (the auricle).annexin V A substance that normally forms a anoxia The absence, or near absence, of oxygen.shield around certain phospholipid molecules in Anoxia can injure tissues of the body.the blood, blocking their entry into coagulation(clotting) reactions. Annexin V is thought to be a ant, fire See fire ant.cause of antiphospholipid syndrome. ant, velvet See velvet ant.anomaly Any deviation from normal, out of theordinary. In medicine, an anomaly is usually some- ant sting See fire ant.thing that is abnormal at birth. antagonist A substance that acts against andanomaly, congenital A birth defect. A minor blocks an action. Antagonist is the opposite of ago-congenital anomaly is an unusual anatomic feature nist. Antagonists and agonists are key players in thesuch as a short second toe that is of no serious med- chemistry of the human body and in pharmacology.ical or cosmetic consequence. By contrast, a majorcongenital anomaly is a defect such as a cleft palate antenatal diagnosis See prenatal diagnosis.that is of serious medical or cosmetic consequence. anterior The front. For example, the breastboneanorexia A decreased appetite or an aversion to is part of the anterior surface of the chest. Oppositefood, resulting in disturbed eating habits and weight of posterior. See also Appendix B, “Anatomicloss. Anorexia may be caused by some medications Orientation Terms.”and medical conditions, particularly in elderly orhospitalized patients. See also anorexia nervosa. anterior cruciate ligament A ligament in the knee that crosses from the underside of the femur to
anterior pituitary 24the top of the tibia. Abbreviated ACL. Injuries to the fever. In a few days, severe respiratory distressACL can occur in a number of situations, including occurs, followed by shock and coma. Prompt recog-sports, and can be quite serious, sometimes requir- nition and treatment are critical. Even with treat-ing surgery. See also knee. ment, the patient may die. Once called woolsorters’ disease.anterior pituitary See pituitary, anterior. anthrax immunization A series of six injectionsanteroposterior From front to back. over a 6-month period, followed by annual boosterAbbreviated AP. When a chest X-ray is taken with the shots, given to military personnel and otherspatient’s back against the film plate and the X-ray (including veterinarians who work with large ani-machine in front of the patient, it is referred to as an mals) who are at high risk of anthrax exposure.AP view. The opposite of AP is posteroanterior (PA).See also Appendix B, “Anatomic Orientation anthrax toxin The toxic substance secreted byTerms.” the bacterium Bacillus anthracis, the cause of the disease anthrax.anthracosis See black lung disease. anti-angiogenesis drug A drug, such as angio-anthrax A highly infectious disease that normally statin or endostatin, that halts the development ofaffects animals, especially ruminants (such as cattle, new blood vessels (angiogenesis).sheep, and horses), but that can be transmitted tohumans by contact with infected animals or their antibiotic A substance produced by one microor-products or by biologic warfare. The agent of ganism that selectively inhibits the growth of another.anthrax is the bacterium Bacillus anthracis. Its Synthetic antibiotics, usually chemically related tospores can resist destruction and remain viable for naturally occurring antibiotics, are made to accom-years. Anthrax is treated with antibiotics such as plish comparable tasks. Antibiotics are used to treatpenicillin, tetracycline, erythromycin, and bacterial infections. See also cephalosporin antibi-ciprofloxin (brand name: Cipro). Three forms of otics; penicillin.disease are caused by anthrax: cutaneous anthrax,inhalation anthrax, and gastrointestinal anthrax. See antibiotic resistance The ability of bacteria andalso anthrax, cutaneous; anthrax, gastrointesti- other microorganisms to resist the effects of annal; anthrax, inhalation. antibiotic to which they were once sensitive. Antibiotic resistance is a major concern of overuseanthrax, cutaneous Anthrax infection of the of antibiotics. Also known as drug resistance.skin. The most common form of anthrax, cutaneousanthrax starts as a red-brown raised spot that antibody A specialized immune protein (anenlarges and has redness, blistering, and hardening immunoglobulin) produced because of the intro-in the area of the spot. The center of the spot then duction of an antigen into the body. An antibody pos-shows an ulcer crater with blood-tinged drainage sesses the remarkable ability to combine with theand the formation of a black crust (an eschar). The antigen that triggered its production. The productionglands in the area become swollen (enlarged lymph of antibodies is a major function of the immune sys-nodes), and the patient may have muscle aching and tem and is carried out by a type of white blood cellpain, headache, fever, nausea, and vomiting. called a B cell, or a B lymphocyte. Antibodies can be triggered by, and directed toward, foreign proteins,anthrax, gastrointestinal Anthrax infection of microorganisms, or toxins. Antibodies that arethe gastrointestinal tract, now very rare but deadly. directed against one’s own tissues are referred to asGastrointestinal anthrax is caused by eating meat autoantibodies. See also immune system.that is contaminated with the bacterium Bacillusanthracis. antibody, antinuclear See antinuclear antibody.anthrax, inhalation Anthrax infection of the anticholinergic Opposing the actions of the neu-lungs, also known as pulmonary anthrax, that is due rotransmitter acetylcholine. Anticholinergic drugsto the inhalation of anthrax spores. The inhaled inhibit the transmission of parasympathetic nervespores multiply rapidly in the lymph nodes in the impulses, thereby reducing spasms of smooth mus-chest. A person infected with inhalation anthrax cles (for example, muscles in the bladder). Sideexperiences local bleeding and tissue death (necro- effects of anticholinergic medications include drysis) in these lymph nodes, and the disease spreads to mouth and related dental problems, blurred vision,the adjacent lung tissue. The first symptoms are sub- tendency toward overheating (hyperpyrexia), and intle, gradual, and somewhat flu-like, including rising some cases, dementia-like symptoms.
25 antiphospholipid syndromeanticipation The progressively earlier appear- antigen-antibody complex The complexance and increased severity of a disease from gen- formed by the binding of an antibody to an antigen.eration to generation. The phenomenon of Antigen-antibody complexes initiate immuneanticipation was once thought to be an artifact, but responses. Also known as an immune complex.a biological basis for it has been discovered in anumber of genetic disorders, such as myotonic dys- antihistamine A drug that opposes the action oftrophy and Huntington disease. histamine released during an allergic reaction by blocking the action of the histamine on the tissue.anti-citrulline antibody See citrulline anti- Antihistamines frequently cause dry mouth andbody. sleepiness. Some antihistamines are nonsedating. Antihistamine side effects that may occur includeanticoagulant An agent that is used to prevent the urine retention in males and increased heart rate.formation of blood clots. Anticoagulants have vari-ous uses. Some are used for the prevention or treat- antihypertensive A medication or another sub-ment of disorders characterized by abnormal blood stance that reduces high blood pressure (hyperten-clots and emboli. Anticoagulant drugs include intra- sion). See also high blood pressure.venous heparin, which acts by inactivating thrombinand several other clotting factors that are required anti-infective An agent that is capable of actingfor a clot to form, and oral anticoagulants such as against infection, either by inhibiting the spread ofwarfarin and dicumarol, which act by inhibiting the an infectious agent or by killing the infectious agentliver’s production of vitamin K–dependent factors outright.that are crucial to clotting. Anticoagulant solutionsare also used for the preservation of stored whole antineoplastic 1 Acting to prevent, inhibit, orblood and blood fractions and to keep laboratory halt the development of a neoplasm (a malignantblood specimens from clotting. tumor, or cancer). 2 An agent with antineoplastic properties. Cancer chemotherapy is antineoplastic.antidepressant A medication that prevents orreduces the symptoms of clinical depression. Some antinuclear antibody An antibody that isantidepressants may also be prescribed for their directed against the structures within the nucleus ofother medical effects, including increasing blood a cell and that is characteristic of autoimmunity.flow within the brain and treating chronic pain. See Abbreviated ANA. ANAs are found in the blood ofalso MAO inhibitor; SSRI; tricyclic antidepressant. patients whose immune systems attack their own body tissues (autoimmunity), such as patients withantidiuretic hormone A peptide hormone systemic lupus erythematosus, rheumatoid arthritis,made in the hypothalamus and released at the base juvenile diabetes mellitus, and Hashimoto disease.of the brain by the nearby pituitary gland. ANAs can also be found in patients with chronicAbbreviated ADH. ADH prevents the production of infections and cancer, and many medications—dilute urine and is therefore antidiuretic. It can also including procainamide (brand name: Procan SR),stimulate contraction of arteries and capillaries, and hydralazine, and phenytoin (brand name:it may have effects on mental function. Also known Dilantin)—can stimulate their production. See alsoas vasopressin. See also ADH secretion, inappro- ANA; autoimmune disorder.priate; pituitary, posterior. antioxidant A substance that reduces damageantiDNAse B A blood test for antibodies to the due to oxygen, such as that caused by free radicals.streptococcus B bacteria. Well-known antioxidants include enzymes and other substances, such as vitamin C, vitamin E, and betaantidote A drug that counteracts a poison. carotene, which are capable of counteracting the damaging effects of oxidation. Antioxidants are alsoantifungal A medication that limits or prevents commonly added to food products such as veg-the growth of yeasts and other fungal organisms. etable oils and prepared foods to prevent or delay their deterioration from the action of air.antigen A substance that the immune system per- Antioxidants may possibly reduce the risks of can-ceives as being foreign or dangerous. The body cer. Antioxidants clearly slow the progression ofcombats an antigen with the production of an anti- age-related macular degeneration.body. antiphospholipid syndrome An immune dis-antigen, prostate specific See prostate spe- order characterized by the presence of abnormalcific antigen test. antibodies in the blood that are directed against the chemical structure of fats that contain phosphorus
antiplatelet agent 26(phospholipids). Abbreviated APS. APS is associated anus The opening of the rectum to the outside ofwith abnormal blood clotting, migraine headaches, the body.recurrent pregnancy loss, and low blood plateletcounts (thrombocytopenia). APS can occur by itself anus, imperforate A birth defect in which the(primary APS) or be caused by an underlying con- rectum is a blind alley and there is no anus.dition (secondary APS), such as systemic lupus ery- Imperforate anus occurs in about 1 in 5,000 births,thematosus. Examples of antiphospholipid and it can be corrected by surgery.antibodies are cardiolipin antibody and lupus anti-coagulant. See also annexin V. anxiety A feeling of apprehension and fear, char- acterized by physical symptoms such as palpita-antiplatelet agent A medication that interferes tions, sweating, and feelings of stress.with the tendency of platelets in the blood to clumpand clot. Aspirin is an antiplatelet agent. anxiety disorder A chronic condition character- ized by an excessive and persistent sense of appre-antiseptic Discouraging the growth of microor- hension, with physical symptoms such as sweating,ganisms. Commonly refers to antiseptic prepara- palpitations, and feelings of stress. Treatmentstions used during medical procedures or used to include the comfort offered by understanding themaintain sanitary conditions in nursing homes, bar- condition, avoiding or desensitizing exacerbating sit-bershops, tattoo parlors, and other facilities where uations, and medications.unchecked microorganism growth could result indisease. See also aseptic. aorta The largest artery in the body, the major conduit from the heart to the body. The aorta arisesantispasmodic A medication that relieves, pre- from the left ventricle of the heart, ascends a little,vents, or lowers the incidence of muscle spasms, arches, and then descends through the chest andespecially those of smooth muscle such as in the the abdomen, ending by dividing into two arteries,bowel wall. the common iliac arteries, that supply blood to the lower extremities. Anatomically, the aorta is tradi-antitoxin 1 An antibody that is naturally produced tionally divided into the ascending aorta, the aorticto counteract a toxin, such as a toxin from a bacter- arch, and the descending aorta. The descendingial infection or snake bite. 2 An antibody from the aorta is, in turn, subdivided into the thoracic aorta,serum of an animal stimulated with specific antibod- which goes from the heart to above the diaphragm,ies that is administered to humans or other animals and the abdominal aorta, which is below theto provide passive immunity to a disease. Such anti- diaphragm. The aorta has branches to the head andtoxins are of short-term value only and are used for neck, the arms, the major organs in the chest andtreatment rather than prevention. abdomen, and the legs. It supplies them all with oxygenated blood. See also abdominal aorta;antiviral agent A medication or another agent ascending aorta; descending aorta; thoracicthat kills viruses or inhibits their capability to repro- aorta.duce. aorta, coarctation of the A constriction of theantro-duodenal motility study A study used to aorta. At the point of coarctation, the sides of thedetect and record the contractions of the muscles of aorta appear to be pressed together. Blood pressurethe stomach and duodenum in order to diagnose is increased above the constriction, and the flow ofmotility disorders of the stomach and small intes- blood is impeded below the level of the constriction.tine. A tube is passed through the nose, throat, Symptoms may not be evident at birth but canesophagus, and stomach, until the tip lies in the develop as soon as the first week after birth, withsmall intestine. The tube senses when the muscles of congestive heart failure or high blood pressure thatthe stomach and small intestine contract and call for early surgery. The outlook after surgery issqueeze it. The contractions are recorded by a com- usually favorable. Some cases of coarctation of theputer and analyzed. aorta have been treated with balloon angioplasty.antrum A general term for a nearly closed cavity aortic aneurysm See aneurysm, aortic.or chamber. For example, the antrum of the stom-ach (gastric antrum) is a portion before the outlet, aortic arch The second section of the aorta fol-which is lined by mucosa and does not produce lowing the ascending aorta. As it continues from theacid. The paranasal sinuses can be referred to as heart, it gives off the brachiocephalic trunk, and thethe frontal antrum, ethmoid antrum, and maxillary left common carotid and subclavian arteries. Theantrum. brachiocephalic trunk splits to form the right sub- clavian and the right common carotid arteries,
27 apoptosiswhich supply blood to the right arm and the right nostril. Each of these objective signs receives 0, 1,side of the neck and head. The left common carotid or 2 points. An Apgar score of 10 means an infantartery and left subclavian artery, the second and is in the best possible condition. The Apgar score isthird branches off the aortic arch, perform parallel done routinely 60 seconds after the birth of thefunctions on the left side. infant. A child with a score of 0 to 3 needs imme- diate resuscitation. The Apgar score is oftenaortic insufficiency Backflow of blood from the repeated 5 minutes after birth, and in the event of aaorta into the left ventricle across a weakened aor- difficult resuscitation, the Apgar score may be donetic valve. Also known as aortic regurgitation. again at 10, 15, and 20 minutes.aortic regurgitation See aortic insufficiency. aphagia Inability to eat.aortic stenosis Narrowing (stenosis) of the aor- aphasia Literally, no speech. Aphasia may also betic valve, the valve between the left ventricle of the used to describe defects in spoken expression orheart and the aorta. This narrowing impedes the comprehension of speech.delivery of blood to the body through the aorta andmakes the heart work harder. The need for surgery apheresis The process of removing a specificdepends on the degree of stenosis. A procedure component from blood temporarily. Also known ascalled balloon valvuloplasty has been used in some hemapheresis and pheresis. Forms of apheresiscases of aortic stenosis. include plasmapheresis, harvesting plasma or liquid part of the blood; leukapheresis, harvesting leuko-aortic valve One of the four valves of the heart. cytes or white blood cells; granulocytapheresis, har-The aortic valve is positioned at the beginning of the vesting granulocytes; lymphocytapheresis,aorta. It normally permits blood from the left ven- harvesting lymphocytes; lymphoplasmapheresis,tricle to flow into the aorta, and prevents blood in harvesting lymphocytes and plasma; and platelet-the aorta from returning to the heart. See also heart pheresis, harvesting platelets.valve. aphonia Inability to speak.aortic valve, bicuspid An abnormal aortic valvewith only two cusps. See also aortic stenosis. apical The adjective for apex, the tip of a pyram- idal or rounded structure, such as the lung or theaortitis Inflammation of the aorta. The causes of heart. For example, an apical lung tumor is a tumoraortitis include syphilis and rheumatic fever. located at the top of the lung.AP 1 Angina pectoris. 2 Arterial pressure. 3 aplasia Failure to develop. See also atrophy.In endocrinology, anterior pituitary gland. 4 Inanatomy, anteroposterior. aplasia of the breast See amastia.aperient Laxative. aplastic anemia See anemia, aplastic.Apert syndrome The best-known type of acro- apnea The absence of breathing (respiration).cephalosyndactyly, a group of disorders character-ized by malformations of the skull, face, hands, and apnea, sleep See sleep apnea.feet. Apert syndrome is inherited as an autosomaldominant trait. See also acrocephalosyndactyly; apophysitis calcaneus Inflammation of thefibroblast growth factor receptor. growth plate of the calcaneus, the bone at the back of the heel, where the Achilles tendon attaches.apex The Latin word for summit, the apex is the Apophysitis calcaneus occurs mainly in older chil-tip of a pyramidal or rounded structure, such as the dren and adolescents, especially active boys. It canlung or the heart. The apex of the lung is indeed its be very painful, although it may be dismissed astip—its rounded most superior portion. The apex “growing pains.” Treatment includes activity limita-of the heart is likewise its tip, but it is formed by the tion, medication, shoe inserts, heel lifts, and some-left ventricle, so it is essentially the most inferior times casting if it becomes especially severe.portion of the heart. Fortunately, it usually disappears as the child gets older. Also known as Sever condition. See alsoApgar score An objective score of the condition Achilles tendon.of a baby after birth. This score is determined byscoring the heart rate, respiratory effort, muscle apoptosis A form of cell death in which a pro-tone, skin color, and response to a catheter in the grammed sequence of events leads to the elimination
appendectomy 28of cells without releasing harmful substances into apraxia The inability to execute a voluntarythe surrounding area. Apoptosis plays a crucial role motor movement despite being able to demonstratein developing and maintaining the health of the body normal muscle function. Apraxia is not related to aby eliminating old cells, unnecessary cells, and lack of understanding or to any kind of physicalunhealthy cells. The human body replaces perhaps paralysis; rather, it is caused by a problem in theone million cells per second. Too little or too much cortex of the brain.apoptosis can play a role in many diseases. Whenapoptosis does not work correctly, cells that should apraxia of speech A severe speech disorderbe eliminated may persist and become immortal, characterized by an inability to speak or a severefor example, in cancer and leukemia. When apopto- struggle to speak clearly. Apraxia of speech occurssis works overly well, it kills too many cells and when the oral-motor muscles do not or cannot obeyinflicts grave tissue damage. This is the case in commands from the brain or when the brain cannotstrokes and neurodegenerative disorders such as reliably send those commands. Apraxia of speech isAlzheimer’s, Huntington’s, and Parkinson’s diseases. caused by damage to the Broca area in the brain.Also known as programmed cell death and cell See also dyspraxia of speech.suicide. APS Antiphospholipid syndrome.appendectomy Surgical removal of the appen-dix. An appendectomy is performed because of apthous ulcer See canker sore.probable appendicitis. See also appendicitis. aqueduct A channel for the passage of fluid.appendicitis Inflammation of the appendix, usu-ally associated with infection of the appendix. aqueduct of Sylvius A canal between the thirdAppendicitis often causes fever, loss of appetite, and and fourth ventricles in the brain within the systempain. Appendicitis may be suspected because of the of four communicating cavities that are continuousmedical history and physical examination. The pain with the central canal of the spinal cord. The ventri-of appendicitis can be located in various areas of cles are filled with cerebrospinal fluid, which is car-the belly. If the appendix ruptures and infection ried by the aqueduct of Sylvius.spreads throughout the abdomen, the pain becomeswidespread as the entire lining of the abdomen aqueduct of the midbrain See aqueduct ofbecomes inflamed. Ultrasonography and computer- Sylvius.ized tomography may be helpful in diagnosis. arachnodactyly A condition in which a personappendix A small outpouching from the begin- has long, spider-like fingers and toes.ning of the large intestine. Arachnodactyly is a frequent finding in those with Marfan syndrome. See also Marfan syndrome.appendix epididymis A small cystic projectionfrom the surface of the epididymis (a structure arachnophobia An abnormal and persistent fearwithin the scrotum that is attached to the backside of spiders. Sufferers from arachnophobia experi-of the testis), which represents a remnant of the ence undue anxiety, even though they realize that theembryologic mesonephros. risk of encountering a spider and being harmed by it is small or nonexistent. They may avoid goingappendix epiploica A finger-like projection of barefoot and may be especially alert when takingfat attached to the colon. showers or getting into and out of bed.appendix testis A small solid projection of tis- arbitration agreement An arrangement insue on the outer surface of the testis, which is a which the patient waives the right to sue the physi-remnant of the embryologic mullerian duct. cian and, instead, agrees to submit any dispute to arbitration. Arbitration agreements are legal andapposition 1 The act of adding or accretion. binding. The arguments in their favor are that, forGrowth by apposition is characteristic of many tis- patients, the case can be settled faster, and moresues in the body by which nutritive matter from the money can go to the patient (rather than to ablood is transformed on the surface of an organ into lawyer). Physicians can often get a discount on theira solid unorganized substance. 2 The act of put- malpractice insurance if the majority of theirting things in juxtaposition or side by side. To lose a patients sign such agreements.pair of apposed teeth is to lose teeth that are next toeach other. Also known as juxtaposition. arbovirus A type of virus transmitted to humans by mosquitoes and ticks. Arbovirus can cause inflammation of the brain (encephalitis). The types
29 arterial pressureof arboviral encephalitis that occur in the US arm, wrist, and hand bones See bones of theinclude LaCrosse, eastern equine, western equine, arm, wrist, and hand.and St. Louis encephalitis, all of which are transmit-ted by mosquitoes. Another arbovirus, Powassan, armed tapeworm See Taenia solium.transmitted by ticks, is a cause of encephalitis in thenorthern US. Many other types of arboviral Arnold Chiari malformation See Chiari mal-encephalitis occur throughout the world. Most are formation.problems only for travelers to countries where theviruses are endemic. One, the West Nile virus, has aromatherapy A form of alternative medicine inmade a major entry into the US. It causes West Nile which essential oils or other scents are inhaled toencephalitis, also known as West Nile fever. See also achieve therapeutic benefit. The mechanism ofhemorrhagic fever, viral. action in aromatherapy is unknown, but recent studies have shown that aromatherapy may be ben-ARC AIDS-related complex. eficial for some health problems.arch, aortic See aortic arch. arrector pili A microscopic band of muscle tis- sue that connects a hair follicle to the dermis. Whenarchaea A unique group of microorganisms that stimulated, the arrector pili contracts and causesare called bacteria (Archaeobacteria) but are genet- the hair to become more perpendicular to the skinically and metabolically different from all other surface, thereby erecting the hair (causing the hairknown bacteria. They appear to be living fossils, the to stand on end). The arrector pili muscle plays asurvivors of an ancient group of organisms that key role in forming goose bumps. See also goosebridged the gap in evolution between bacteria and bumps.multicellular organisms (eukaryotes). arrhythmia An abnormal heart rhythm. With anarcus senilis A cloudy opaque arc or circle arrhythmia, the heartbeats may be irregular or tooaround the edge of the eye, often seen in the eyes of slow (bradycardia), too rapid (tachycardia), or toothe elderly. early. When a single heartbeat occurs earlier than normal, it is called a premature contraction. SeeARDS Acute respiratory distress syndrome. also bradycardia; tachycardia.areola 1 The small, darkened area around the arrhythmia, atrial An abnormal heart rhythmnipple of the breast. 2 The colored part of the iris due to electrical disturbances in the upper cham-around the pupil of the eye. 3 Any small space in bers of the heart (atria) or the atrioventricular (AV)a tissue. node “relay station,” leading to fast heart beats. Examples of atrial arrhythmias include atrial fibril-arginine An essential amino acid and a key com- lation, atrial flutter, and paroxysmal atrial tachycar-ponent of protein. Lack of arginine in the diet dia.impairs growth, and in adult males it decreases thesperm count. Arginine is available in turkey, arrhythmia, ventricular An abnormally rapidchicken, and other meats, and as L-arginine in sup- heart rhythm that originates in the lower chambersplements. Babies born without the enzyme phos- of the heart (ventricles). Ventricular arrhythmiasphate synthetase have arginine deficiency syndrome; include ventricular tachycardia and ventricular fib-adding arginine to their diets permits normal rillation. Both are life-threatening arrhythmias, andgrowth and development. they are most commonly associated with heart attacks or scarring of the heart muscle from previ-argyria Silver poisoning, resulting in ashen, gray, ous heart attacks.discolored skin, and damage to other tissues of thebody. Caused by long-term use of silver salts or arterial anastomosis A joining of two arteries.other preparations containing silver. See also anastomosis.arm In popular usage, the appendage that arterial aneurysm See aneurysm, arterial.extends from the shoulder to the hand. However, themedical definition refers to the upper extremity arterial blood gas See ABG.extending from the shoulder only to the portion ofthe elbow, excluding the forearm, which extends arterial pressure The pressure of the bloodfrom the elbow to the wrist. The arm contains one within an artery. Also known as arterial tension andbone: the humerus. intra-arterial pressure.
arterial tension 30arterial tension See arterial pressure. artery, coronary See coronary artery.arteriogram An X-ray in which an injection of artery spasm, coronary See coronary arterydye shows blood vessels. spasm.arteriole A small branch of an artery that leads to arthralgia Pain in a joint.a capillary. The oxygenated hemoglobin (oxyhemo-globin) makes the blood in arterioles (and arteries) arthritis Inflammation of a joint. When joints arelook bright red. inflamed, they can develop stiffness, warmth, swelling, redness, and pain. There are more thanarteriosclerosis Hardening and thickening of 100 types of arthritis. See also ankylosingthe walls of the arteries. Arteriosclerosis leads to spondylitis; arthritis, degenerative; arthritis,heart attacks and strokes, as well as to peripheral gouty; arthritis, Lyme; psoriatic arthritis; arthri-vascular disease. Arteriosclerosis can be catego- tis, Reiter; arthritis, rheumatoid; arthritis,rized as atherosclerosis, medial calcification, hyper- spondylitis; gout; lupus; pseudogout.tensive, or arteriolar sclerosis. See alsoatherosclerosis; heart attack; stroke; peripheral arthritis, degenerative A type of arthritisvascular disease. caused by inflammation, breakdown, and eventual loss of the cartilage of the joints. Degenerativearteriosclerotic aneurysm See aneurysm, arthritis is the most common form of arthritis, usu-arteriosclerotic. ally affecting the hands, feet, spine, and large weight-bearing joints, such as the hips and knees.arteriovenous malformation See malforma- Also known as osteoarthritis and degenerative jointtion, arteriovenous. disease.arteritis, cranial A serious disease character- arthritis, gouty See gouty arthritis.ized by inflammation of the walls of arteries, partic-ularly those that supply blood to the head. arthritis, Lyme Joint inflammation associatedSymptoms include headache, pain in the jaw when with Lyme disease, a bacterial disease spread byrepetitively chewing, and tenderness of the scalp, ticks. See also Lyme disease.usually over the inflamed arteries of the sides of thehead (temporal area). Less specific symptoms arthritis, psoriatic See psoriatic arthritis.include fatigue, low-grade fever, and weight loss.The muscle aching of polymyalgia rheumatica is arthritis, Reiter The joint component of a syn-seen in one-fourth of patients with cranial arteritis. drome of inflammation of the joints (arthritis), eyesWhen the arteries affected by cranial arteritis (conjunctivitis), and the genitourinary and/or gas-become inflamed, they can narrow to the degree trointestinal systems. See also Reiter syndrome.that the blood flow through them is limited. This cancause serious deficiency of oxygen supply to the tis- arthritis, rheumatoid An autoimmune diseasesues that are normally supplied by these arteries. characterized by chronic inflammation of joints.Deficient oxygenation of the eyes or brain can lead Rheumatoid disease can also involve inflammationto impaired or double vision, blindness, or stroke. of tissues in other areas of the body, such as thePatients with cranial arteritis are usually over 50 lungs, heart, and eyes. Because it can affect multipleyears of age. The disease is detected by a biopsy of organs of the body, rheumatoid arthritis is referredan artery and treated with high dose cortisone- to as a systemic illness. Although rheumatoid arthri-related medications. Also known as temporal arteri- tis is a chronic illness, patients may experience longtis and giant cell arteritis. See also polymyalgia periods without symptoms. Also known as rheuma-rheumatica. toid disease.arteritis, giant cell See arteritis, cranial. arthritis, septic Joint inflammation caused by infection from blood poisoning (sepsis) or fromarteritis, temporal See arteritis, cranial. infection within the affected joint itself, or as a side effect of infection in other body tissues. Treatmentartery A blood vessel that carries blood, rich in includes antibiotic medications and surgicaloxygen, away from the heart to the body. The oxy- drainage. Also known as pyarthosis and suppurativegenated hemoglobin (oxyhemoglobin) in arterial arthritis.blood makes it look bright red. See also aorta;carotid artery; ophthalmic artery; radial artery; arthritis, spondylitis A form of arthritis thatsplenic artery; vertebral artery. causes chronic inflammation of the spine.
31 artificial insemination by partnerarthritis, systemic-onset chronic rheumatoid arthroscope A thin, flexible fiberoptic scope thatSee arthritis, systemic-onset juvenile rheuma- is introduced into a joint space through a small inci-toid. sion in order to carry out diagnostic and treatment procedures within the joint. An arthroscope is fittedarthritis, systemic-onset juvenile rheumatoid with a miniature camera, a light source, and preci-A form of joint disease in children whose systemic sion tools at the end of flexible tubes. See alsosigns and symptoms include high intermittent fever, arthroscopy.a salmon-colored skin rash, swollen lymph glands,enlargement of the liver and spleen, inflammation of arthroscopic Related to arthroscopy.the lungs (pleuritis), and inflammation around theheart (pericarditis). The arthritis itself may not be arthroscopy A surgical technique in which aimmediately apparent, but in time it surfaces and tube-like instrument is inserted into a joint tomay persist after the systemic symptoms are long inspect, diagnose, and repair tissues. It is mostgone. Also known as systemic-onset chronic arthri- commonly performed in patients with diseases oftis or Still’s disease. the knees or shoulders.arthritis in children Arthritis in children, usu- arthrosis See joint.ally in the form of juvenile/pediatric arthritis orrheumatoid arthritis. See also arthritis, systemic- articulation 1 In medicine, the joint whereonset juvenile rheumatoid. bones come together. See also joint. 2 In den- tistry, the occlusal surfaces of the teeth, where thearthritis mutilans An extremely severe form of teeth come together. 3 In speech, the productionchronic rheumatoid or psoriatic arthritis character- of intelligible words and sentences by joiningized by resorption of bones and the consequent col- together the lips, tongue, palate, and other struc-lapse of soft tissue. When this affects the hands, it tures.can cause a phenomenon sometimes referred to as“telescoping fingers.” articulation disorder A speech disorder involv- ing difficulties in articulating specific types ofarthrocentesis A procedure in which a sterile sounds. Articulation disorders often involve substi-needle and syringe are used to drain fluid from the tution of one sound for another, slurring of speech,joint. This is usually done as an office procedure or or indistinct speech. Treatment is speech therapy.at the bedside in the hospital. For certain condi-tions, medication is put into the joint after fluid artificial heart A human-made heart. An artifi-removal. The needle is then removed, and a band- cial heart is a mechanical pump that is used toage or dressing is applied over the entry point. Joint replace a damaged heart temporarily or perma-fluid can be examined to determine the cause of the nently.joint swelling, such as infection, gout, or rheuma-toid disease. Arthrocentesis can be helpful in reliev- artificial insemination A procedure in which aing joint swelling and pain. Also known as joint fine catheter (tube) is inserted through the cervix intoaspiration. the uterus to directly deposit a sperm sample. The purpose of this relatively simple procedure is toarthrogryposis Joint contractures that develop achieve fertilization and pregnancy. Also known asbefore birth and are evident at birth. With arthro- intrauterine insemination (IUI).gryposis there is a lack of the normal range ofmotion in one or more joints. In normal embryonic artificial insemination by donor A procedure indevelopment, joints can be seen moving by 8 weeks which a fine catheter (tube) is inserted through theof gestation. This motion of joints is essential to the cervix into the uterus to directly deposit a sperm sam-proper development of the joints and structures ple from a donor other than the woman’s mate. Thearound them. Limitation of joint motion before birth purpose of this procedure is to achieve fertilization andleads to joint contractures and arthrogryposis. pregnancy. Abbreviated AID. Also known as heterolo-Prenatal limitation of joint mobility can result from gous insemination.neurologic deficits, muscle defects, connective tis-sue defects, and fetal crowding (in which there is artificial insemination by partner A procedurenot enough room for the fetus to move around in which a fine catheter (tube) is inserted through thefreely in the womb). cervix into the uterus to deposit a sperm sample from the woman’s mate directly into the uterus. The pur-arthropathy Joint disease. pose of this procedure is to achieve fertilization and pregnancy. Abbreviated AIH. Also known as homolo- gous insemination.
artificial pacemaker 32artificial pacemaker A device that uses electri- iron absorption. Ascorbic acid can cause adversecal impulses to regulate the heart rhythm or repro- reactions when taken with some drugs.duce it. An internal pacemaker is one in which theelectrodes to the heart, the electronic circuitry, and ASCUS An acronym for Atypical Squamous Cellsthe power supply are all implanted internally, within of Undetermined Significance. This term is used inthe body. Although there are different types of pace- the Bethesda System for reporting Pap smear find-makers, all are designed to treat a heart rate that is ings, and indicates that some flat (squamous) cellstoo slow (bradycardia). Pacemakers may function look unusual and may or may not be pre-malignantcontinuously and stimulate the heart at a fixed rate, or malignant.or they may function at an increased rate duringexercise. A pacemaker can also be programmed to ASD Atrial septal defect.detect an overly long pause between heartbeats andthen stimulate the heart. aseptic Free from infection, sterile. See also anti- septic.artificial pancreas A machine that constantlymeasures glucose (sugar) in the blood and, in aseptic necrosis See avascular necrosis.response to an elevated level of glucose, releases anappropriate amount of insulin. In this respect, an ASO Antistreptolysin-O, a blood test that looks forartificial pancreas functions like a natural pancreas. antibodies to the streptococcus A bacteria. Also abbreviated ASLO.asbestos A natural material made up of tinyfibers that is used as thermal insulation. Inhalation aspartate aminotransferase An enzyme that isof asbestos fibers can lead to asbestosis and normally present in liver and heart cells that ismesothelioma. released into the blood when the liver or heart is damaged. Abbreviated AST. Some medications canasbestosis Scarring of the lungs caused by also raise blood AST levels. Also known as seruminhalation of asbestos fibers. When asbestos fibers glutamic oxaloacetic transaminase (SGOT).lodge in the lungs, they promote the development ofcancer, such as mesothelioma of the pleura (the lin- Asperger syndrome A disorder related toing of the lung) and bronchogenic carcinoma (can- autism characterized by obsessive interests andcer of the lung). See also mesothelioma. behavior, but without speech delay or mental retar- dation. Other features of Asperger syndromeascaris Intestinal roundworms. Infection with include physical clumsiness, and/or moderate toascaris is referred to as ascariasis. severe social deficits. Asperger syndrome is the mildest of and at the highest functioning end of theascending aorta The first section of the aorta, spectrum of pervasive developmental disorders (thewhich starts from the left ventricle of the heart and autism spectrum). Persons with Asperger syndromeextends to the aortic arch. The right and left coro- have deviations or abnormalities in three broadnary arteries that supply blood to the heart muscle aspects of development: social relatedness andarise from the ascending aorta. social skills, the use of language for communicative purposes, and certain behavioral and stylistic char-ascites An abnormal accumulation of fluid within acteristics that involve repetitive or perseverativethe abdomen. There are many causes of ascites, features and a limited but intense range of interests.including cirrhosis of the liver, cancer within the See also autism.abdomen, congestive heart failure, and tuberculosis. aspergillosis Infection with the fungusascorbic acid Vitamin C, an essential nutrient Aspergillus, seen especially in people with compro-found mainly in fruits and vegetables. The body mised immune systems in whom there may be inva-requires ascorbic acid in order to form and main- sive lung infection and sometimes spread to othertain bones, blood vessels, and skin. Ascorbic acid tissues, including the brain, the skin, and bones.also promotes the healing of cuts, abrasions and Aspergillosis also causes allergic sinusitis and aller-wounds; helps fight infections; inhibits conversion gic bronchopulmonary disease.of irritants in smog, tobacco smoke, and certainfoods into cancer-causing substances; appears to Aspergillus A family of fungal organisms andlessen the risk of developing high blood pressure molds, some of which can cause disease.and heart disease; helps regulate cholesterol levels;prevents the development of scurvy; appears to asphyxia Impaired breathing.lower the risk of developing cataracts; and aids in
33 asthma, exercise-inducedaspirate To suck in. For example, a person may for mute individuals, and closed-captioning systemsaspirate by accidentally drawing material from that help the hearing impaired enjoy televisionthe stomach into the lungs, and a physician can shows and videos. See also augmentative commu-aspirate fluid from a joint. See also arthrocentesis; nication device.aspiration. association 1 In the study of birth defects (dys-aspiration 1 Removal of a sample of fluid and morphology), the nonrandom occurrence in two orcells through a needle. 2 The accidental sucking more individuals of a pattern of multiple anomaliesof food, fluid, vomit, or other foreign material into not known to be a malformation syndrome (such asthe lungs. Down syndrome), a malformation sequence of events, or a field defect, in which all the defects areaspiration, joint See arthrocentesis. concentrated in one particular area of the body. An example of an association in dysmorphology is theaspiration pneumonia Inflammation of the VATER association. 2 In genetics, the occurrencelungs due to aspiration. together of two or more characteristics more often than would be expected by chance alone.aspirin Once the Bayer trademark for acetylsali- Association is to be distinguished from linkage. Ancylic acid, now the common name for this anti- example of association involves a feature on the sur-inflammatory pain reliever. face of white blood cells, the human leukocyte anti- gen (HLA) type. HLA type B-27 is associated with anassay 1 An analysis done to determine the pres- increased risk for a number of diseases, includingence and amount of a substance. An assay may be ankylosing spondylitis.done, for example, to determine the level of thyroidhormones in the blood. 2 An analysis done to association, VACTERL See VACTERL associa-determine the biologic or pharmacologic potency of tion.a drug. For example, an assay may be done of a vac-cine to determine its potency. 3 As a verb, to try or Association of American Medical Colleges Aattempt. For example, “She assayed this operation nonprofit association of accredited medical schoolsfor the first time and was understandably nervous.” in the US and Canada that is responsible for the4 The act of analyzing a mixture for one or more of Medical College Admission Test (MCAT), anits components. 5 The act of judging the value or entrance examination for medical schools.worth of something. AST Aspartate aminotransferase.assistant, physician See physician assistant. asthenia Weakness. Lack of strength.assisted living A type of long-term care facilityfor elderly or disabled people who are able to get asthenic 1 Having a slender, light body.around on their own but who may need help with Ectomorphic. 2 Weak. Lacking in strength.some activities of daily living or simply prefer theconvenience of having their meals in a central cafe- asthma A common lung disorder in whichteria and having nursing staff on call. inflammation causes the bronchi to swell and nar- row the airways, creating breathing difficulties thatassisted suicide Deliberate hastening of death may range from mild to life-threatening. Symptomsperformed by a terminally ill patient, with assistance include shortness of breath, cough, wheezing, andfrom a physician, a family member, or another indi- chest tightness. The diagnosis of asthma is based onvidual. See also active euthanasia. evidence of wheezing and is confirmed with breath- ing tests. Many allergens and irritants can precipi-assistive device A device that is designed, made, tate attacks of asthma. Avoidance of precipitatingor adapted to help a person perform a particular factors can be helpful. Treatment may includetask. For example, canes, crutches, walkers, wheel- lifestyle changes, activity reduction, allergy shots,chairs, and shower chairs are all assistive devices. and medications to prevent or reverse the bron-See also assistive technology. chospasm.assistive technology An assistive device or, more asthma, exercise-induced Asthma triggered bycommonly, some kind of electronic or computerized vigorous physical activity. It primarily affects chil-device that helps a disabled person to function more dren and young adults because of their high levelseasily in the world. Examples of assistive technology of physical activity, but it can occur at any age.include devices that allow people to control a com- Exercise-induced asthma is initiated by the fall inputer with the mouth, keyboards that can “speak” airway temperature during rapid breathing followed
asthma, thermally induced 34by rapid reheating with lowered ventilation. The recurrent sinus and lung infections. Abbreviated AT.more heat that is transferred, the cooler the airways Patients with AT have a striking predisposition tobecome, and the more rapidly the airways rewarm, leukemia and lymphoma and are extremely sensitivethe more the bronchi are narrowed. Acute attacks to radiation. Other features include difficulty swal-can be minimized by warming up before strenuous lowing and slowed growth. AT is inherited as an auto-activity. An inhalator may also be used before exer- somal recessive trait.tion. Also known as exercise-induced bron-chospasm and thermally induced asthma. ATCC American Type Culture Collection.asthma, thermally induced See asthma, exer- atelectasis Failure of full expansion of the lung atcise-induced. birth, or lung collapse thereafter. Also known as collapsed lung.astigmatism A common form of visual impair-ment in which part of an image is blurred due to an atelectasis, primary Failure of full expansion ofirregularity in the dome-shaped curvature of the the lung at birth.front surface of the eye, the cornea. With astigma-tism, light rays entering the eye are not uniformly atelectasis, secondary Partial or complete col-focused on the retina. The result is blurred vision at lapse of a previously expanded lung. Secondaryall distances. Significant astigmatism can cause atelectasis may occur when full chest expansion isheadaches, eye strain, and seriously blurred vision. difficult, such as after chest surgery.Astigmatism is often not detected during routine eyescreening in schools. It may coexist with other athelia Absence of the nipple. Athelia tends torefractive errors such as nearsightedness and far- occur on one side (unilaterally) in children with thesightedness. Astigmatism is corrected with slightly Poland syndrome and on both sides (bilaterally)cylindrical lenses that have greater light-bending with certain types of ectodermal dysplasia. Atheliapower in one direction than the other. Use of these also occurs in association with progeria (prematurelenses elongates objects in one direction and short- aging). See also amastia; amazia; Poland syn-ens them in the other, much like looking into a dis- drome; progeria.torting wavy mirror. atherectomy A procedure to remove plaqueastrocytoma A tumor that begins in the brain or (atheroma) from the inside of a blood vessel.spinal cord in small, star-shaped cells called astro- Atherectomy is done most often in major arteries,cytes. The location of the tumor depends on the age such as the coronary, carotid, and vertebral arter-of the person. In adults, astrocytomas most often ies, that have experienced the occlusive effects ofarise in the cerebrum, whereas in children, they may atherosclerosis. Atherectomy may be accomplishedarise in the brain stem, cerebrum, and cerebellum. by various means, including angioplasty, laser sur- gery, conventional surgical incision, or use of aasymptomatic Without symptoms. For example, small drill-tipped catheter. In the US, atherectomy isan asymptomatic infection is an infection with no nicknamed the “Rotorooter” procedure, after asymptoms. company that cleans out drainage pipes.asystole A dire form of cardiac arrest in which atheroma A fatty deposit in the inner liningthe heart stops beating and there is no electrical (intima) of an artery, resulting from atherosclero-activity in the heart. As a result, the heart is at a total sis. Also called an atherosclerotic plaque, an arte-standstill. rial plaque, or a plaque.ataxia Poor coordination and unsteadiness due atherosclerosis The presence of fatty lipidto the brain’s failure to regulate the body’s posture deposits in the lining (intima) of an artery.and regulate the strength and direction of limb Atherosclerosis is a form of arteriosclerosis. Seemovements. Ataxia is usually due to disease in the also arteriosclerosis.cerebellum of the brain, which lies beneath theback part of the cerebrum. atherosclerotic Pertaining to atherosclerosis. Atherosclerotic heart disease is the leading cause ofataxia-telangiectasia A progressive disease char- death in the US. See atherosclerosis.acterized by degeneration of the nervous system man-ifest by poor coordination and balance (cerebellar athetosis Involuntary writhing movements, par-ataxia), red eyes due to widening of small blood ves- ticularly of the arms and hands. Athetosis is associ-sels in the conjunctiva (ocular telangiectasia), and ated with several neurological disorders, such as cerebral palsy and Rett syndrome.
35 atropine psychosisathlete’s foot A skin infection caused by a fun- atrial septal defect A hole in the wall (septum)gus called Trichophyton that thrives within the between the upper chambers of the heart (atria).upper layer of the skin when it is moist, warm, and Abbreviated ASD. ASD is a major class of heart mal-irritated. The fungus can be found on floors and in formation. Usually, when clots in veins break offsocks and clothing, and it can be spread from per- (embolize), they travel first to the right side of theson to person through contact with these objects. heart and then to the lungs, where they lodge. WhenHowever, without proper growing conditions, ath- there is an ASD, however, a clot can cross from thelete’s foot fungus will not infect the skin. It can be right to the left side of the heart, and then pass intotreated with topical antifungal preparations. Also the arteries as a paradoxical embolism. Once a clotknown as tinea pedis, athlete’s foot is a form of is in the arterial circulation, it can travel to theringworm. brain, block a vessel there, and cause a stroke. ASDs are surgically closed.atlantoaxial joint The joint between the first(atlas) and second (axis) vertebrae of the neck atrial septum The wall between the right and leftbeneath the skull. The axis features a bony promi- atria of the heart.nence called the odontoid process, about which theatlas rotates. The atlantoaxial joint is a pivot type of atrioventricular Pertaining to the upper cham-joint. It allows the head to turn from side to side. bers of the heart (atria) and the lower chambers ofThe atlantoaxial joint is supported and strengthened the heart (ventricles).by the capsular, anterior, and posterior atlantoaxialand by the transverse ligaments. Also known as atrioventricular node The electrical relay sta-atloaxoid joint. tion between the upper and lower chambers of the heart. Abbreviated AV node. Electrical signals fromatlas The first vertebra in the neck. It supports the atria must pass through the AV node to reach thethe head at the base of the skull. Also known as first ventricles. The AV node, which controls the heartcervical vertebra. rate, is one of the major elements in the cardiac conduction system. The AV node serves as an elec-atonic Without normal muscle tone or strength. trical relay station, slowing the electrical currentAn atonic seizure is one in which the person sud- sent by the sinoatrial (SA) node before the signal isdenly loses muscle tone and strength; the person permitted to pass down through to the ventricles.cannot sit or stand upright and, unless supported, This delay ensures that the atria have an opportunityfalls down. to fully contract before the ventricles are stimulated. After passing the AV node, the electrical currentatopic dermatitis A skin disease characterized travels to the ventricles, along special fibers embed-by areas of severe itching, redness, scaling, and loss ded in the walls of the lower part of the heart.of the surface of the skin. Atopic dermatitis is themost common of the many types of eczema. Atopic atrium An entry chamber. On both sides of thedermatitis is frequently associated with other aller- heart, the atrium is the chamber that leads to thegic disorders, especially asthma and hay fever. A ventricle.defect of the immune system within the skin hasbeen detected in patients who have atopic dermati- atrophic vaginitis Thinning of the liningtis, but the reason for the defect is unknown. (endothelium) of the vagina due to decreased pro- duction of estrogen. Atrophic vaginitis may occurATP 1 Acute thrombocytopenic purpura. 2 with menopause.Adenosine triphosphate. atrophy A wasting away or diminution. Muscleatresia Absence of a normal opening, or failure atrophy is a decrease in muscle mass, often due toof a structure to be tubular. Atresia can affect many extended immobility.structures in the body. For example, esophagealatresia is a birth defect in which part of the esopha- atropine A drug, made from the belladonnagus is not hollow, and with anal atresia, there is no plant, that is administered via injection, eye drops,hole at the bottom end of the intestine. or in oral form to relax muscles by inhibiting nerve responses.atria The plural of atrium. atropine psychosis A syndrome characterizedatrial arrhythmia See arrhythmia, atrial. by dry mouth, blurred vision, forgetfulness, and dif- ficulty with urination that can be caused by the anti-atrial fibrillation See fibrillation, atrial. cholinergic effects of some drugs, particularly antipsychotic medications. Treatment requires
attack, vasovagal 36reducing or stopping the medication. See also audiology The study of hearing.anticholinergic. audiometry The measurement of hearing.attack, vasovagal See vasovagal reaction. auditory acuity The clarity or clearness of hear-attention The act of attending to discrete stimuli ing, a measure of how well a person hears. Auditoryin the environment. Learning is most efficient when acuity is measured in order to determine a person’sa person is paying attention. Poor attention can be a need for a hearing aid.key sign of behavior disorders in children, stress, ordepression. See also attention deficit hyperactivity auditory tube See Eustachian tube.disorder. augmentative communication device A physi-attention deficit disorder See attention cal, mechanical, or electronic device that helps adeficit hyperactivity disorder. person with a speech impairment to communicate. Augmentative communication devices range fromattention deficit hyperactivity disorder A dis- books of pictures or words that the patient canorder in which a person is unable to control behav- show to express thoughts, to computers that areior due to difficulty in processing neural stimuli, capable of synthesizing complex speech.accompanied by an extremely high level of motoractivity. Abbreviated ADHD. ADHD can affect chil- aura A sensation perceived by a patient that pre-dren and adults, but it is easiest to perceive during cedes a condition affecting the brain. An aura oftenschooling. A child with ADHD may be extremely dis- occurs before a migraine or seizure. It may consisttractible, unable to remain still, and very talkative. of flashing lights, a gleam of light, blurred vision, anADHD is diagnosed by using a combination of par- odor, the feeling of a breeze, numbness, weakness,ent and/or patient interview, observation of the or difficulty in speaking..patient, and sometimes use of standardized screen-ing instruments. Treatments include making adjust- aural vertigo, recurrent See Ménière’s dis-ments to the environment to accommodate the ease.disorder, behavior modification, and the use ofmedications. Stimulants are the most common auricle 1 The principal projecting part of the ear,drugs used, although certain other medications can also known as pinna. 2 A structure that is ear-be effective. shaped, like the atrium of the heart, which is also referred to as the auricle of the heart.attenuate To weaken, or to make or becomethin. auricular Of or pertaining to the outer ear, or to something else that is ear-shaped, such as theattenuated virus A weakened, less vigorous atrium of the heart.virus. An attenuated virus may be used to make avaccine that is capable of stimulating an immune auricular fibrillation See fibrillation, atrial.response and creating immunity, but not of causingillness. auscultate To listen, for diagnostic purposes, to the sounds made by the internal organs of the body.atypical Unusual, or not fitting a single diagnostic For example, nurses and physicians auscultate thecategory. lungs and heart of a patient by using a stethoscope placed on the patient’s chest or back.atypical measles syndrome The modifiedexpression of measles, as may occur in persons who autism A spectrum of neuropsychiatric disorderswere incompletely immunized against measles or characterized by deficits in social interaction andwho have compromised immune systems. communication and by unusual and repetitiveAbbreviated AMS. AMS begins suddenly with high behavior. Some, but not all, people with autism arefever, headache, cough, and abdominal pain. A rash nonverbal. Autism is normally diagnosed before agemay appear 1 to 2 days later, often beginning on 6, and it may be diagnosed in infancy in some cases.the limbs. Swelling (edema) of the hands and feet The cause of autism is currently unknown, althoughmay occur. Pneumonia is common. See also it is believed to involve an inherited or acquiredmeasles. genetic defect involving multiple chromosomes, possibly including chromosomes 6, 15, 17, and/oraudiogram A test of hearing at a range of sound the X chromosome. Autism is not caused by emo-frequencies. tional trauma, as was once theorized. Autistic or autistic-like behavior may be caused by other
37 autosomalneurological conditions—particularly the seizure autoimmunity The state of being attacked bydisorder Landau-Kleffner syndrome—certain forms one’s own immune system. Patients whose misdi-of encephalitis, and several genetic disorders, rected immune systems attack their own body tis-including Angelman syndrome and Rett syndrome. sues are said to have autoimmunity. See alsoAlso known as Kanner syndrome or infantile autism. antinuclear antibody; autoimmune disorder.See also Asperger syndrome; elective mutism;fragile X syndrome; Landau-Kleffner syndrome; autologous In blood transfusion and transplan-Prader-Willi syndrome; Rett syndrome. tation, a situation in which the donor and recipient are the same person. Patients scheduled for non-autistic disorder Autism, particularly the most emergency surgery may be autologous donors byserious form of autism. donating blood for themselves that will be stored until the surgery. An autologous graft is a graft (suchautoantibody An antibody that is directed as a graft of skin) that is provided for oneself.against the patient’s own body. Autoantibodies play acausative role in a number of diseases, such as automated external defibrillator A device thatrheumatoid arthritis, systemic lupus erythematosus, automatically analyzes the heart rhythm and that—and Hashimoto disease. See also autoimmune if it detects a problem that may respond to an elec-disorder. trical shock—delivers a shock to restore a normal heart rhythm. Thanks to their small size and ease ofautoclave A chamber for sterilizing with steam use, AEDs have been installed in many settingsunder pressure. The original autoclave was essen- (such as schools and airports), and serve a role intially a pressure cooker in which steam tightened expanding the number of opportunities for life-sav-the lid. ing defibrillation. Abbreviated AED.autogenous Self-produced. automatism A behavior that is performed with- out conscious knowledge and that does not appearautograft Tissue transplanted from one part of to be under conscious control. This curious type ofthe body to another in the same individual. Also behavior occurs in a number of neurological andknown as an autotransplant. psychiatric disorders. The neurologic disorders associated with automatism include narcolepsy andautoimmune disorder A condition character- some forms of epilepsy. The psychiatric conditionsized by autoimmunity in which a misdirected associated with automatism include schizophreniaimmune system acts against the tissues of one’s own and fugue states. Automatism involves doing some-body. Autoimmune disorders typically feature thing “automatically” and not remembering after-inflammation of various tissues of the body and are ward how one did it or even that one did it. Alsoassociated with antinuclear antibodies (ANAs) in the known as automatic behavior. See also epilepsy;blood. Examples of autoimmune disorders include seizure disorders.systemic lupus erythematosus, Sjogren’s syndrome,rheumatoid arthritis, polymyositis, scleroderma, autonomic nervous system A part of the nerv-Hashimoto disease, juvenile (type 1) diabetes melli- ous system that regulates key involuntary functionstus, Addison disease, vitiligo, pernicious anemia, of the body, including the activity of the heart mus-glomerulonephritis, and pulmonary fibrosis. cle; the smooth muscles, including the muscles ofAutoimmune disorders are more frequent in women the intestinal tract; and the glands. The autonomicthan in men. It is thought that the estrogen of nervous system has two divisions: the sympatheticfemales may influence the immune system to pre- nervous system, which accelerates the heart rate,dispose some women to autoimmune disorders. constricts blood vessels, and raises blood pressure,Furthermore, the presence of one autoimmune dis- and the parasympathetic nervous system, whichorder increases the chance for developing another slows the heart rate, increases intestinal and glandsimultaneous autoimmune disorder. See also anti- activity, and relaxes sphincter muscles.nuclear antibody. autopsy A postmortem examination. Also knownautoimmune hemolytic anemia A condition in as necropsy.which the immune system destroys red blood cells,resulting in fewer of these oxygen-transporting cells. autosomal Pertaining to a chromosome that isSee also hemolytic anemia. not a sex chromosome. People normally have 22 pairs of autosomes (44 autosomes) in each cell,autoimmune thyroiditis See Hashimoto dis- together with 2 sex chromosomes, X and Y in a maleease. and X and X in a female.
autosomal dominant trait 38autosomal dominant trait A genetic trait that avulsion Tearing away. A nerve can be avulsed byappears in patients who have received one copy of a an injury, as can part of a bone.specific autosomal (nonsex) gene for that particulartrait. For example, achondroplasia, Marfan syn- axilla Armpit.drome, and Huntington disease are autosomal dom-inant traits. axillary Pertaining to the armpit, the cavity beneath the junction of the arm and the body.autosomal recessive trait A genetic trait thatappears only in patients who have received two axillary dissection Removal of a portion of thecopies of a specific autosomal (nonsex) gene for lymph nodes under the arm.that particular trait, one from each parent. Forexample, sickle cell anemia and cystic fibrosis are axis The second cervical vertebra. The first cervi-autosomal recessive traits. cal vertebra (atlas) rotates around the odontoid process of the axis. See also atlas; atlantoaxialautosome Any chromosome other than the X and joint.Y sex chromosomes. People normally have 22pairs of autosomes (44 autosomes) in each cell. axon A long fiber of a nerve cell (neuron) that acts somewhat like a fiber-optic cable to carry out-aux Prefix indicating growth or increase. going messages. The neuron sends electrical impulses from its cell body through the axon to tar-AV 1 Atrioventricular. Relating to the atrium(atria) get cells. Each nerve cell has one axon. An axon canand ventricle(s) of the heart. 2 Arteriovenous. be over a foot in length. See also dendrite; neuron.Relating to an artery(ies) and a vein(s). Ayurveda India’s traditional, natural system ofAV node Atrioventricular node. medicine that has been practiced for more than 5,000 years. Ayurveda provides an integratedavascular necrosis A condition in which poor approach to preventing and treating illness throughblood supply to an area of bone leads to bone death. lifestyle interventions and natural therapies.Abbreviated AVN. Also known as aseptic necrosis Ayurvedic theory states that all disease begins withand osteonecrosis. an imbalance or stress in the individual’s con- sciousness. Lifestyle intervention is a majoravian influenza A highly contagious viral disease ayurvedic preventive and therapeutic approach.with up to 100 percent mortality in domestic fowl.Caused by influenza A virus subtypes H5 and H7. All azotemia A higher-than-normal blood level of ureatypes of birds are susceptible to the virus, but out- or other nitrogen-containing compounds. The hall-breaks occur most often in chickens and turkeys. mark test for azotemia is the serum blood urea nitro-The infection may be brought by migratory wild gen (BUN) level. Azotemia is usually caused by thebirds which can carry the virus, but show no signs of inability of the kidneys to excrete these compounds.disease. Humans are only rarely affected. Alsoknown as fowl plague, avian flu, and bird flu. AZT Azidothymidine, now renamed zidovudine, but still best known by the abbreviation AZT. ThisAVM Arteriovenous malformation. See malfor- antiviral drug is prescribed, usually in combinationmation, arteriovenous. with protease inhibitors and other drugs, to treat HIV infection in patients with AIDS.
back pain, low Pain in the lower back area that Bb can be caused by problems with the lumbar spine, the discs between the vertebrae, the ligaments around the spine and discs, the spinal cord and nerves, muscles of the low back, internal organs of the pelvis and abdomen, or the skin covering the lumbar area. See also sciatica. backbone The spine, a flexible row of bones stretching from the base of the skull to the tailbone. See also vertebral column. bacteremia The presence of live bacteria in theB cell A type of white blood cell that has an bloodstream. Also known as bacillemia. See alsoimportant role in producing antibodies for the blood culture; septicemia.immune system. B cells are lymphocytes that maturein the bone marrow (as opposed to T cells, lym- bacteria Single-celled microorganisms that canphocytes that mature in the thymus). Many B cells exist either as independent (free-living) organismsgo on to become plasma cells and produce anti- or as parasites (dependent on another organism forbodies (immunoglobulins); some B cells mature life). The plural of bacterium. Examples of bacteriainto memory B cells. See also memory B cell; include Acidophilus, a normal inhabitant of yogurt;plasma cell. Gonococcus which causes gonorrhea; Clostridium welchii, the most common cause of gangrene; E.B variant GM2-gangliosidosis See Tay-Sachs coli, which lives in the colon and can cause diseasedisease. elsewhere; and Streptococcus, the bacterium thatB. quintana See Bartonella quintana. causes the common throat infection called strep throat.Babinski reflex A reflex used to determine ade-quacy of the higher (central) nervous system. The bacteria, flesh-eating See necrotizing fasci-Babinski reflex is obtained by stimulating the out- itis.side of the sole of the foot, causing extension of the bacterial Of or pertaining to bacteria, as in abig toe while fanning the other toes. The examiner bacterial lung infection.begins the stimulation at the heel and goes forwardto the base of the toes. Most newborn babies and bacterial vaginosis A vaginal condition charac-young infants are not neurologically mature, and terized by an abnormal vaginal discharge due to anthey therefore show a Babinski reflex. A Babinski overgrowth of normal bacteria in the vagina.reflex in an older child or an adult is abnormal and Women with bacterial vaginosis also have feweris a sign of a problem in the brain or spinal cord. A than the usual population of vaginal bacteria, calledBabinski reflex that is present on one side but not lactobacilli. Symptoms of bacterial vaginosis arethe other is also abnormal, and it can indicate vaginal discharge and sometimes a fishy odor. Awhich side of the brain is involved. Also known as microscopic sign of bacterial vaginosis is anplantar response, big toe sign, and Babinski phe- unusual vaginal cell called a clue cell. Treatmentnomenon, response, or sign. options include oral antibiotics and vaginal gels. Bacterial vaginosis can cause premature labor andbaby teeth See primary teeth. delivery, as well as infection of the amniotic fluidbacillus A large family of bacteria that are rod- and of the uterus after delivery. Therefore, screen-like in shape. They include the bacteria that cause ing and treatment for bacterial vaginosis duringfood to spoil, as well as those that are responsible pregnancy may be done.for some diseases. Helpful members of the bacillus bacteriocidal Capable of killing bacteria.family are used to make antibiotics or colonize the Antibiotics, antiseptics, and disinfectants can all behuman intestinal tract and aid with digestion. bacteriocidal.back pain Pain felt in the low or upper back. bacteriophage A virus that lives within a bac-Causes of pain in the low and upper back include terium, replicating itself and eventually destroyingconditions affecting the bony spine; discs between the bacterial cell. Bacteriophages have been verythe vertebrae; ligaments around the spine and discs; helpful in the study of bacterial and molecularspinal inflammation; spinal cord and nerves; mus- genetics. They are sometimes simply called phages.cles; internal organs of the pelvis, chest, andabdomen; tumors; and the skin.
bacteriostatic 40bacteriostatic Capable of inhibiting the growth ies. Recurrent narrowing at the site of balloon infla-or reproduction of bacteria. See also bacteriocidal. tion can still develop following successful coronary angioplasty. See also coronary artery disease.bacterium Singular of bacteria. See also bacteria. balloon tamponade A procedure in which abag of waters The amniotic sac and amniotic balloon is inflated within the esophagus or stomach,fluid. to apply pressure on bleeding blood vessels, com- press the vessels, and stop the bleeding. It is used inBaker cyst A swelling in the space behind the the treatment of bleeding veins in the esophagusknee (the popliteal space) that is composed of a (esophageal varices) and stomach. Also known asmembrane-lined sac filled with synovial fluid that esophagogastric tamponade.has escaped from the joint. Also known as synovialcyst of the popliteal space. banding of chromosomes Treatment staining of chromosomes to reveal characteristic patterns ofbalanitis Inflammation of the rounded head (the horizontal bands. Thanks to these banding patterns,glans) of the penis. Inflammation of the foreskin is which resemble bar codes, each human chromo-called posthitis. In the uncircumcised male, balani- some is distinctive and can be identified withouttis and posthitis generally occur together as bal- ambiguity. Banding also permits the detection ofanoposthitis: inflammation of both the glans and chromosome deletions (lost segments), duplicationsforeskin. (extra segments), and other structural abnormalities.balanitis, circinate A skin inflammation around barbiturate A class of drugs that depresses activ-the penis in males with Reiter syndrome. With circi- ity in the brain and spinal cord (central nervous sys-nate balanitis, the skin around the shaft and tip of the tem), including many sleeping pills, sedatives,penis can become inflamed and scaly. Cortisone antispasmodics, and anesthetics. Barbiturates arecreams can be used as treatment. See also balanitis; addictive, carry a high risk of overdose, and shouldkeratodermia blennorrhagicum; Reiter syndrome. never be used with alcohol or with other nervous system depressants.balanoposthitis Inflammation of both the glanspenis and foreskin. An uncircumcised boy should bariatric surgery Surgery on the stomachbe taught to clean his penis with care to prevent and/or intestines to help a person with extreme obe-infection and inflammation of the foreskin and the sity lose weight. Bariatric surgery is an option forglans. Cleaning of the penis is done by gently people who have a body mass index (BMI) aboveretracting the foreskin, only to the point where 40. It is also an option for people with a BMIresistance is met. Full retraction of the foreskin may between 35 and 40 who have health problems likenot be possible until after age 3. See also balanitis; type 2 diabetes or heart disease. Types of bariatricposthitis. surgery include gastric banding and gastric bypass. See also bariatrics.baldness Lack or loss of hair on the scalp. Alsoknown as alopecia. There are many types of bald- bariatrician A physician who specializes inness, each with a different cause. Baldness may be bariatrics. See bariatrics.localized to the front and top of the head, as in thevery common type of male-pattern baldness; bald- bariatrics The field of medicine that focuses onness may be patchy, a condition called alopecia persons who are overweight using a comprehensiveareata; or it may involve the entire head, as in alope- program including diet and nutrition, exercise,cia capitis totalis. See alopecia; alopecia areata; behavior modification, lifestyle changes, and, whenalopecia capitis totalis; alopecia, traumatic; indicated, the prescription of appetite suppressantsalopecia universalis. and other appropriate medications. Bariatrics also includes research into overweight, as well as itsball-and-socket joint A joint in which the causes, prevention, and treatment. See alsoround end of a bone fits into the cavity of another bariatric surgery.bone. The hip joint is a ball-and-socket joint. barium enema An enema using a white, chalkyballoon angioplasty Coronary angioplasty that solution containing barium, in preparation foris accomplished by using a balloon-tipped catheter series of X-ray images of the lower intestineinserted through an artery in the groin or arm, to (colon). The barium outlines the colon on the X-rayenlarge a narrowing in a coronary artery. Angioplasty film.is commonly successful in opening coronary arter-
41 base pairbarium solution A liquid that contains barium abraded skin or into the whites of the eyes. Trenchsulfate, which produces a visible image on X-ray fever was first recognized in the trenches of Worldfilm. Barium solution outlines organs of the body so War I, and it now occurs among homeless people,they can be seen as images on X-ray film. injection drug users, street alcoholics, and others who live in cramped, unhygienic quarters. B. quin-barium sulfate An odorless, flavorless barium tana is also responsible for a disease called bacillarysalt. Barium is a metallic chemical element. See also angiomatosis in people infected with HIV, and forbarium enema; barium solution; barium swallow. infection of the heart and great vessels (endocardi- tis) in people with bloodstream infection (bac-barium swallow A test that involves filling the teremia). Also known as Rochalimaea quintana. Seeesophagus, stomach, and small intestines with a also trench fever.barium solution in preparation for an X-ray, todefine the anatomy of the upper digestive tract. Also basal cell A small, round cell found in the lowerknown as upper gastrointestinal series. part, or base, of the epidermis.barosinusitis See aerosinusitis. basal cell carcinoma The most common type of skin cancer, which commonly presents as a sorebarotitis See aerotitis. that seems to get better and then recurs and may start to bleed. Basal cell carcinoma often occurs onBarr body A microscopic feature of female cells the face and neck, where the skin is exposed to sun-that is due to the presence of two X chromosomes, light. These tumors are locally invasive and tend toone of which is inactive and crumples up. burrow in but not metastasize (spread) to distant locations.Barrett esophagus A complication of chronicsevere gastrointestinal reflux disease (GERD) that basal ganglia A region of the base of the braininvolves a change in the type of cells that line the that consists of three clusters of neurons (caudateinner wall of the lower esophagus. There is a small nucleus, putamen, and globus pallidus) that arebut definite increased risk of cancer of the esopha- responsible for involuntary movements such asgus (adenocarcinoma) in people with Barrett tremors, athetosis, and chorea. The basal gangliaesophagus. The diagnosis of Barrett esophagus is are abnormal in a number of important neurologicmade on seeing (through endoscopy) a pink conditions, including Parkinson’s disease andesophageal lining (mucosa) that extends a short Huntington’s disease.distance (usually less than 2.5 inches) up theesophagus from the gastroesophageal junction and basal metabolic rate The rate of metabolism, asfinding cell changes on biopsy of the lining. measured by the amount of heat given off when aTreatment involves acid-suppression drugs and fol- person is at rest; it is expressed as calories of energylowup monitoring of the esophagus is advised. per hour per square meter of skin. The basal meta- bolic rate can offer clues about underlying healthbarrier method A birth control method that problems. For example, a person with an overlyemploys a barrier which prevents sperm from active thyroid has an elevated basal metabolic rate.entering the cervix, thereby preventing conception.Condoms and diaphragms are examples of a barrier basal temperature 1 Usually, a person’s tem-method. See also cervical cap; condom; condom, perature on awakening in the morning. Becausefemale; diaphragm. changes in basal temperature accompany ovulation, basal temperature is often tracked by women whoBartholin gland One of a pair of glands between want to ensure or avoid pregnancy. 2 A crudethe vulva and the vagina that produce lubrication in measure of thyroid function that is achieved by tak-response to stimulation. Along with a second pair of ing and comparing basal temperatures. This meas-nearby glands, called the lesser vestibular glands, ure is now superceded by modern thyroid functionthe Bartholin glands act to aid in sexual intercourse. blood tests. Also known as Broda test.Also known as greater vestibular gland. base A unit of DNA. There are four bases in DNA:Bartonella henselae See cat scratch disease. adenine (A), guanine (G), thymine (T), and cyto- sine (C). The sequence of bases (for example, CAG)Bartonella quintana A parasitic microorganism constitutes the genetic code.in the rickettsiae family that can multiply within thegut of a louse and can then be transmitted to base pair Two DNA bases that are complemen-humans and cause trench fever. Transmission tary to one another (A and T, or G and C) and joinoccurs when infected louse feces are rubbed into
base sequence 42in strands to form the double-helix that is charac- who are confined to a bed or wheelchair, and theyteristic of DNA. can be prevented by moving the patient frequently, changing bedding, and keeping the skin clean andbase sequence The particular order of dry. Also known as pressure sore, decubitus sore,nucleotide bases in a DNA molecule. and decubitus ulcer.baseline Information or data gathered at the bedwetting Involuntary urination in bed after thebeginning of a period from which variations that usual age of toilet training. Also known as nighttimesubsequently develop are compared. enuresis and nocturnal enuresis. It may be caused by incomplete development of bladder control, abasement membrane A thin membrane that is sleep or arousal disorder, bladder or kidney dis-composed of a single layer of cells. ease, neurological problems, or psychological causes (such as fear of the dark that prevents thebasophil A type of white blood cell (leukocyte) child from leaving the bed). About 20 percent of 5-with coarse, bluish-black granules of uniform size year-olds wet the bed at least once a month; sur-within the cytoplasm. Basophils are so named prisingly, bedwetting can persist into teenage.because their cytoplasmic granules stain with basic Treatment depends on the cause and may includedyes. Basophils normally constitute 0.5 to 3 percent education, behavior modification techniques, theof the peripheral blood leukocytes, and contain his- use of alarms, bladder-retention training, and med-tamine and serotonin. Also known as a basophilic ication. See also enuresis.leukocyte. bee sting An area of skin affected by piercingbasophilic leukocyte See basophil. from the stinger of a bee. A bee sting can trigger an allergic reaction, including life-threatening anaphy-battered child syndrome A condition in which lactic shock. Avoidance and prompt treatment area person has skeletal fractures, especially multiple essential for those who are allergic to bee stings.injuries of various ages, that result from child Self-injectible adrenaline can be carried by personsabuse. All states in the US have adopted laws man- known to be allergic when in risk areas. Hikersdating the reporting of suspected instances of child should wear long pants and shirts in risk areas. If aabuse. See also child abuse. person is attacked, he or she should run for shelter, covering the face to prevent airway stings. Treatmentbattle fatigue The World War II name for what is depends on the severity of symptoms. Stingersknown today as post-traumatic stress disorder should be removed promptly, and the area should(PTSD). See also post-traumatic stress disorder. be cleansed with soap and water. Ice packs, painBCG Bacille Calmette Guérin, a weakened (atten- medications, and anti-itching medications can beuated) version of a bacterium called helpful in treating local reactions. Victims withMycobacterium bovis that is closely related to more serious symptoms can require intravenousMycobacterium tuberculosis, the agent responsible fluids, oxygen, cortisone medicine, or epinephrine,for tuberculosis. See tuberculosis vaccination. as well as medications to open the breathing pas- sages. In selected cases, allergy injection therapy isBeau’s lines Transverse lines or grooves across highly effective for prevention. For those who arethe fingernails, or transverse depressions in the nail not allergic, stings are a minor nuisance unless theyplate, from temporary disturbance of cell division occur in multiples.where the nail develops. The condition may becaused by local disease or injury of the nail fold, or bee sting, Africanized A sting from anfrom a generalized condition such as an illness or a Africanized (“killer”) bee, a species of large honeydrug, for example, chemotherapy. bees found in South and Central America, as well as in some parts of the US. This species of bees has anbedbug A blood-sucking bug in the Cimex family unusual and dangerous natural defense mechanismthat lives hidden in bedding or furniture and comes when disturbed. A loud noise or vibration, such asout at night to bite its victims. a barking dog or lawn mower, near a hive may cause the bees to display aggressive behavior. Theybedsore A painful, often reddened area of degen- attack in large numbers and for a longer period oferating, ulcerated skin that is caused by pressure time than is typical of the common European honeyand lack of movement and is worsened by exposure bee. As a result, Africanized bees inflict more stings,to urine or other irritating substances. Untreated injecting a higher dosage of bee venom into theirbedsores can become seriously infected or gan- victims. See also bee sting.grenous. Bedsores are a major problem for patients
43 Bernard-Soulier syndromebeef tapeworm The most common of the large benign Not malignant. A benign tumor is one thattapeworms that parasitize people. Beef tapeworm does not invade surrounding tissue or spread tocan be contracted from infected beef that is raw or other parts of the body; it is not a cancer.rare. Also known as Taenia saginata. benign intracranial hypertension Seebehavior modification The use of rewards pseudotumor cerebri.and/or punishments to encourage desirable behav-ior. benign partial epilepsy with centro-temporal spikes See epilepsy, benign rolandic.behavioral disorder A condition characterizedby undesirable behavior that is within the patient’s benign prostatic hyperplasia A common, non-control (for example, substance abuse and antiso- cancerous enlargement of the prostate gland. Thecial behavior). enlarged prostate may compress the urinary tube (urethra), which courses through the center of thebehavioral medicine An interdisciplinary field prostate, impeding the flow of urine from the blad-of research and practice that focuses on how peo- der through the urethra to the outside. Abbreviatedple’s thoughts and behavior affect their health. BPH. If BPH is severe enough, complete blockageBehavioral medicine is concerned, for example, can occur. BPH generally begins after age 30,with undesirable behaviors such as drug abuse, and evolves slowly, and causes symptoms only after ageutilizes behavior therapy techniques such as 50. Half of men over age 50 develop symptoms ofbiofeedback, relaxation training, and hypnosis. BPH, but only a minority need medical or surgical intervention. Medical therapy includes drugs suchbehaviorism The science of studying and modi- as finasteride and terazosin. Prostate surgery hasfying animal or human behavior, often through traditionally been seen as offering the most bene-behavior modification techniques. fits—and the most risks—for BPH. BPH is not a sign of prostate cancer. Also known as benign pro-Behcet’s syndrome A chronic disease featuring static hypertrophy and nodular hyperplasia of theinflammation of small blood vessels and character- prostate.ized by a triad of features: ulcers in the mouth,ulcers of the genitalia, and inflammation of the eye benign rolandic epilepsy of childhood See(uveitis). The mouth ulcers typically present as epilepsy, benign rolandic.recurring crops of aphthous ulcers. Arthritis is alsocommonplace. The cause of Behcet’s syndrome is bereavement The period after a loss duringnot known. It is more frequent and severe in which grief is experienced and mourning occurs.patients from the Eastern Mediterranean and Asia The duration of bereavement depends on both howthan in those of European descent. attached the person was to the person (or pet) who died, and the amount of preparation time anticipat-belching A normal process of releasing through ing the loss.the mouth air that accumulates in the stomach,thereby relieving distention. Upper abdominal dis- beriberi Inflammation of multiple nervescomfort associated with excessive swallowed air (polyneuritis), heart disease (cardiopathy), andmay extend into the lower chest, producing symp- edema (swelling) due to a deficiency of thiaminetoms that suggest heart or lung disease. (vitamin B1) in the diet.Bell’s palsy Paralysis of the nerve that supplies Bernard-Soulier syndrome A disorder inthe facial muscles on one side of the face (the sev- which the platelets crucial to normal blood clottingenth cranial nerve, or facial nerve). Bell’s palsy lack the ability to adequately stick to injured bloodoften starts suddenly. The cause may be a viral infec- vessel walls, leading to abnormal bleeding.tion. Treatment includes protecting the eye on the Bernard-Soulier syndrome usually appears in theaffected side from dryness during sleep. Massage of newborn period, infancy, or early childhood, withaffected muscles can reduce soreness. Sometimes bruises, nosebleeds, and gum bleeding. Bernard-cortisone medication, such as prednisone, is given Soulier syndrome is an inherited disease, transmit-to reduce inflammation during the first weeks of ill- ted as an autosomal recessive trait. There is noness. The outlook is generally good; the vast major- specific treatment. Bleeding episodes may requireity of patients recover within weeks or months. platelet transfusions. Specific platelet function tests, as well as tests for the glycoproteins common tobelly See abdomen. Bernard-Soulier syndrome, can confirm the diagno- sis. Also known as giant platelet syndrome.belly button The navel or umbilicus; the formersite of attachment of the umbilical cord.
Bernstein test 44Bernstein test A test to find out if heartburn is the progression of HIV-related disease, although itcaused by acid in the esophagus, and so to diagnose may also indicate cell destruction due toGERD (gastroesophageal reflux disease). The test cytomegalovirus or other causes.involves dripping a mild acid, similar to stomachacid, through a tube placed in the esophagus. Also beta-adrenergic blocking drug See betaknown as esophageal acid infusion test. blocker.berry aneurysm See aneurysm, berry. bezoar A clump or wad of swallowed food or hair. Bezoars can block the digestive system, espe-beta blocker A class of drugs that block the cially the exit of the stomach. A bezoar composed ofeffect of beta-adrenergic substances such as adren- hair is called a trichobezoar. A bezoar composed ofaline (epinephrine), that play a key role in the sym- vegetable materials is called a phytobezoar. Apathetic portion of the involuntary nervous system. bezoar composed of hair and food is called a tri-By blocking the action of the sympathetic nervous chophytobezoar.system on the heart, they slow the heartbeat andrelieve stress on the heart. Beta blockers are used to BF Physician’s shorthand for black female.treat abnormal heart rhythms, specifically to preventabnormally fast heart rates (tachycardias) or irreg- bi- Prefix indicating two, as in biceps (a muscleular heart rhythms, such as premature ventricular with two heads) or bicuspid (having two flaps orbeats. Because beta blockers reduce the demand of cusps).the heart muscle for oxygen, they can be useful intreating angina. They have also become important bias In a clinical research trial, the effects thatdrugs in improving survival after a heart attack. Due may cause an incorrect conclusion. Common exam-to their effect on blood vessels, beta blockers can ples of bias include advanced knowledge of thelower the blood pressure and are of value in the treatment being given, strong desire of thetreatment of hypertension. Other uses include the researcher for a specific outcome, or improperprevention of migraine headaches and the treatment study design. To avoid bias, a blinded study may beof familial or hereditary essential tremors. Beta done. See also blinded study; double-blindedblockers reduce pressure within the eye and they study.are therefore used to lessen the risk of damage tothe optic nerve and loss of vision in patients with bicarbonate In medicine, bicarbonate usuallyglaucoma. Beta blockers include acebutolol (brand refers to bicarbonate of soda (sodium bicarbonate,name: Sectral), atenolol (brand name: Tenormin), baking soda), a white powder that is a commonbisoprolol (brand name: Zebeta), metoprol (brand ingredient in antacids. Also, the bicarbonate level isnames: Lopressor, Lopressor LA, Toprol XL), an indirect measure of the acidity of the blood thatnadolol (brand name: Corgard), and timolol is determined when electrolytes are tested. The nor-(brand name: Blocadren). Topical beta blockers for mal serum range for bicarbonate is 22–30the eye include timolol ophthalmic solution (brand mmol/liter.name: Timoptic) and betaxolol hydrochloride biceps A muscle that has two heads, or origins.(brand name: Betoptic). There is more than one biceps muscle. The bicepsbeta carotene A protective antioxidant vitamin brachii is the well-known flexor muscle in the upperthat is a natural component of carrots. See also arm; it bulges when the arm is bent in a C-shapeAppendix C, “Vitamins.” with the fist toward the forehead. The biceps femoris is in the back of the thigh.beta cell, pancreatic A cell that makes insulinand is found in the areas of the pancreas called the bicornuate Having two horns or horn-shapedislets of Langerhans. Destruction of beta cells branches. The uterus is normally unicornuate, but itcauses type 1 (insulin-dependent) diabetes melli- can sometimes be bicornuate.tus. See also diabetes mellitus. bicuspid Having two flaps or cusps.beta error The statistical error (said to be “of the bicuspid aortic valve An aortic valve in thesecond kind,” or type II) that is made in testing heart that has two flaps (cusps) that open and close.when it is concluded that something is negative when A normal aortic valve in the heart has three flaps.it really is positive. Also known as false negative. There may be no symptoms of bicuspid aortic valvebeta-2 microglobulin A nonspecific test that in childhood, but in time the valve may become nar-measures the amount of cell destruction present. It rowed, making it harder for blood to pass throughis considered to be one of the best ways to measure it, or blood may start to leak backward through the
45 biliary sludgevalve (regurgitate). Treatment depends on how the the urinary tract or the intestine, where they hatchvalve is working. For a severely deteriorated valve, to form another form of the parasite, calledreplacement surgery may be necessary. miracidia, that can then infect snails again, com- pleting the parasite’s life cycle. Also known as schis-bicuspid valve See mitral valve. tosomiasis.b.i.d. An abbreviation commonly used on pre- biliary Having to do with the gallbladder, bilescriptions that means twice a day. See also Appendix ducts, or bile. The biliary system consists of the gall-A, “Prescription Abbreviations.” bladder, bile ducts, and bile. See also bile.bifid Split in two. biliary cirrhosis, primary See cirrhosis, pri- mary biliary.bifid uvula See uvula. biliary sand A term used by surgeons to describebig toe sign See Babinski reflex. small particles in bile that are visible to the naked eye and are large enough to be counted easily in abilateral Affecting both sides. For example, bilat- gallbladder that has been removed. Biliary sand mayeral arthritis affects joints on both the left and right be looked upon as a stage of growth between bilarysides of the body. sludge, which is made up of microscopic particles, and gallstones. The composition of biliary sandbile A yellow-green fluid that is made by the liver varies but is similar to that of gallstones, the mostand stored in the gallbladder. Bile passes through common components being cholesterol crystals andthe common bile duct into the duodenum, where it calcium salts. Biliary sand may cause no symptoms,helps digest fat. The principal components of bile or it may cause intermittent symptoms, includingare cholesterol, bile salts, and the pigment biliru- pain in the abdomen, nausea, and vomiting, partic-bin. Cholesterol is normally kept in liquid form by ularly after a fatty meal. Biliary sand can cause com-the dissolving action of the bile salts. An increased plications, including inflammation of the pancreasamount of cholesterol in the bile overwhelms the (pancreatitis) and inflammation of the gallbladderdissolving capacity of the bile salts and leads to the (cholecystitis). Biliary sand can often be detected byformation of cholesterol gallstones. Similarly, a defi- an ultrasound of the abdomen. If patients with bil-ciency of bile salts promotes cholesterol gallstone iary sand develop symptoms or complications, gall-formation. See also gallstone. bladder removal (cholecystectomy) is performed. See also gallstone.bile acid resin A substance that binds in theintestine with bile acids that contain cholesterol and biliary sludge Microscopic particulate matter inis then eliminated in the stool. The major effect of bile. The composition of biliary sludge varies. Thebile acid resin is to lower LDL-cholesterol. Bile acid most common particulate components are choles-resin may be prescribed, together with a statin med- terol crystals and calcium salts. Biliary sludge hasication, for patients with heart disease, to reduce been associated with certain conditions, includingcholesterol. Cholestyramine (brand name: rapid weight loss, fasting, pregnancy, the use of cer-Questran) and colestipol (Colestid) are examples of tain medications (for example, ceftriaxone,bile acid resins. Side effects may include constipa- octreotide), and bone marrow or solid organ trans-tion, bloating, nausea, and gas. Although bile acid plantation. However, it most commonly occurs inresin is not absorbed, it may interfere with the individuals with no identifiable conditions. Biliaryabsorption of other medicines if taken at the same sludge can be considered microscopic gallstones.time as the other medicines. See also statin. Biliary sludge usually causes no symptoms, and it may appear and disappear over time. It may, how-bile sludge See biliary sludge. ever, cause intermittent pain in the abdomen, oftenbilharzia A schistosome, a trematode worm par- with nausea and vomiting. Biliary sludge may alsoasite. Three main species of these worms— cause more serious complications, includingSchistosoma haematobium, S. japonicum, and S. inflammation of the pancreas (pancreatitis) andmansoni—cause disease in humans. Larval forms inflammation of the gallbladder (cholecystitis).of the parasite live in freshwater snails. When the Biliary sludge can be detected with ultrasound of theparasite is liberated from the snail, it burrows into abdomen, or by directly examining bile contentthe skin, transforms to the schistosomulum stage, under a microscope. If patients with biliary sludgeand migrates to the urinary tract (S. haematobium), develop symptoms or complications, the gallblad-or liver or intestine (S. japonicum or S. mansoni), der may be removed. See also gallstone.where the adult worms develop. Eggs are shed into
bilirubin 46bilirubin A yellow-orange compound that is pro- and selection as agents of change. New variants induced by the breakdown of hemoglobin from red biologic evolution are often harmful, and when theseblood cells. new variants are transmitted from parents to off- spring, this occurs according to classical genetics.binaural Relating to both ears. While hearing Humans require cultural as well as biological evolu-aids may be binaural (in both ears) or monaural tion. See also cultural evolution.(in just one ear), binaural aids are generally con-sidered to be superior. Synonymous with stereo- biological response modifier A substance thatphonic. stimulates the body’s response to infection and dis- ease. Abbreviated BRM. The body naturally pro-binge drinking The dangerous practice of con- duces small amounts of certain BRMs. Some BRMssuming large quantities of alcoholic beverages in a are made in the laboratory in large amounts for usesingle session. Binge drinking carries a serious risk in treating cancer, rheumatoid arthritis, Crohn’s dis-of harm, including alcohol poisoning. See also ease, hepatitis, and other diseases. BRMs used inalcohol poisoning. biological therapy include monoclonal antibodies, interferon, interleukin-2 (IL-2), and colony-stimu-binge eating disorder An eating disorder char- lating factor. Also known as biologics.acterized by periods of extreme overeating, but notfollowed by purging behaviors, as in bulimia. Binge biological therapy Treatment to stimulate oreating disorder can occur alone or in association restore the ability of the immune system to fight infec-with abnormality of the brain’s hypothalamus gland, tion and disease. Biological therapy is thus any formPrader-Willi disorder, or other medical conditions. of treatment that uses the body’s natural abilities toIt can contribute to high blood pressure, weight cause the immune system to fight infection, treat dis-gain, diabetes, and heart disease. Treatment may ease, or to protect the body from side effects of treat-include therapy, dietary education and advice, and ment. For example, biological therapy to block themedication. action of a messenger of inflammation, called tumor necrosis factor (TNF), is being used to treat condi-binocular vision The ability to maintain visual tions such as Crohn’s disease and rheumatoid arthri-focus on an object with both eyes, creating a single tis. Also known as biotherapy or immunotherapy. Seevisual image. Lack of binocular vision is normal in also biological response modifier.infants. Adults without binocular vision experiencedistortions in depth perception and visual measure- biomarker A biologic feature that can be used toment of distance. measure the presence or progress of disease or the effects of treatment. For example, prostate specificbio- Prefix indicating living plants or creatures, antigen (PSA) is a biomarker for cancer of theas in biology (the study of living organisms). prostate.biofeedback A method of treatment that uses a biopsy The removal of a sample of tissue formonitor to measure patients’ physiologic informa- examination under a microscope to check for can-tion of which they are normally unaware. By watch- cer cells or other abnormalities.ing a monitor, patients can learn by trial and error toadjust their thinking and other mental processes in biopsy, endometrial A procedure for samplingorder to control “involuntary” bodily processes such the lining of the uterus (the endometrium).as blood pressure, temperature, gastrointestinal Endometrial biopsy is usually done to detect thefunctioning, and brain wave activity. Biofeedback is cause of abnormal uterine bleeding, but it may benow used to treat a wide variety of conditions and used to determine the cause of infertility, test fordiseases, including stress, alcohol and other addic- uterine infections, and even monitor responses totions, sleep disorders, epilepsy, respiratory prob- certain medications. The procedure can be done inlems, fecal and urinary incontinence, muscle a physician’s office. There are few risks, the mostspasms, partial paralysis, muscle dysfunction common being cramping and pain. Oral pain med-caused by injury, migraine headaches, hyperten- ications taken beforehand may help reduce cramp-sion, and a variety of blood vessel conditions, ing and pain. See also biopsy.including Raynaud’s phenomenon. biopsy, excisional A surgical procedure inbioflavinoid An antioxidant compound that is which an entire abnormal area is removed for diag-found in various plants and is available in supple- nostic examination under a microscope.ment form. Once known as vitamin P. biopsy, incisional A surgical procedure inbiologic evolution A process mediated by genes which only a portion of an abnormal area isthat shows a slow rate of change and uses mutations
47 birth controlremoved for diagnostic examination under a micro- require special action for public health prepared-scope. An incisional biopsy is used when the abnor- ness. Examples of Category A diseases includemal area is too large for excisional biopsy or when anthrax, botulism, the plague, smallpox, tularemia,excision would destroy important tissue or pose a and hemorrhagic fever due to the Ebola andcosmetic problem. See also biopsy, excisional. Marburg viruses. Category B agents are moderately easy to disseminate; cause moderate morbidity andbiopsy, needle A procedure in which a small low mortality; and require specific enhancements ofamount of tissue is taken for examination by using a the CDC’s diagnostic capacity and enhanced diseasehollow needle. See also biopsy; biopsy, stereotac- surveillance. Examples of Category B diseasestic needle. include Q fever, Brucellosis, Glanders, Ricin toxin, epsilon toxin of the gas gangrene bacillus, andbiopsy, punch See punch biopsy. Staphylococcus enterotoxin B. Category C agents are emerging pathogens that could be engineered forbiopsy, sentinel-lymph-node Examination of mass dissemination in the future because of theirthe first lymph node that receives lymphatic availability; ease of production and dissemination;drainage from a tumor to learn whether that node and potential for high morbidity and mortality andhas tumor cells in it. The sentinel node’s identity is major health impact. Examples of Category C dis-determined by injecting around the tumor a tracer eases include Nipah virus, Hantavirus, tickbornesubstance that travels through the lymphatic system hemorrhagic fever and encephalitis viruses, Yellowto the first draining node, thereby identifying it. If fever, and Tuberculosis (multi-drug-resistant TB).the sentinel node contains tumor cells, removal ofmore nodes in the area may be warranted. If the bipolar disorder A disorder, formerly calledsentinel node is normal, extensive dissection of the manic-depressive illness, in which the patient cyclesregional lymphnode basin is generally not required. through uncontrollable mood states. Less prevalentSee also biopsy. than simple clinical depression, bipolar disorders involve cycles of depression, hypomania (elevatedbiopsy, stereotactic needle A procedure in mood), mania (extremely elevated mood), and inwhich the spot to be biopsied is located three- some cases psychosis. Sometimes the mooddimensionally, the information is entered into a switches are dramatic and rapid, but most often theycomputer, and then the computer calculates the are gradual. Both depression and mania affectinformation and positions a needle to remove the thinking, judgment, and social behavior in ways thatbiopsy sample. Stereotactic needle biopsy can be cause serious problems. For example, unwise busi-done in a properly equipped physician’s office, and ness, financial, and personal decisions may beit carries a minimal amount of pain and risk com- made when an individual is in a manic phase.pared to other types of biopsy. See also biopsy. Bipolar disorder is usually a chronic recurring con- dition, with serious impairment and suicide com-biotechnology The fusion of biology and tech- mon in untreated cases. The cause is as yetnology, the application of biological techniques to unknown, although bipolar disorders appear toproduct research and development. In particular, have a strong genetic basis and may be influencedbiotechnology involves the use by industry of by seasonal patterns, hormones, or viral infection. Arecombinant DNA, cell fusion, and new bioprocess- strategy that combines medication and psychosocialing techniques to produce large molecules useful in treatment is optimal for managing bipolar disease.treating and preventing disease. Slang biotech. Also known as manic-depressive disease and manic depression. See also cyclothymia; seasonal affec-bioterrorism Terrorism using biologic agents tive disorder; depression; mania; mixed mania.that are harmful to humans. Biological diseases andthe agents that might be used for terrorism have birth The process of delivering a fetus from thebeen listed by the US Centers for Disease Control uterus. Normally, the fetus is expelled through theand Prevention (CDC). These agents include cervix and birth canal with the assistance of rhyth-viruses, bacteria, rickettsiae (microorganisms that mic muscle contractions. Birth may instead be ahave traits common to both bacterial and viruses), surgical procedure: a Caesarean section. See alsofungi, and biological toxins. The biologica disease caesarean section.agents are classified into three categories, accord-ing to the degree of danger each agent is felt to pose. birth control The practice of exercising someCategory A poses high risk to national security level of control over contraception. Birth controlbecause they can be easily disseminated or trans- methods are many, and they vary in effectiveness.mitted from person to person; cause high mortality, The most effective method is abstinence from sex,with the potential for major public health impact; followed by oral, injectible, or implanted contra-might cause public panic and social disruption; and ceptives; barrier methods used consistently and
birth control pill 48with spermicidal gel; and the basal temperature bitewing X-ray A dental X-ray that depicts howmethod, if used carefully and consistently. See also the teeth fit together on one side of the mouth.barrier method; cervical cap; coitus interruptus;condom; condom, female; contraceptive; contra- BKA Below-the-knee amputation. See amputa-ceptive, emergency; contraceptive, implanted; tion.Depo-Provera; diaphragm; intrauterine device;natural family planning; oral contraceptive. Black Death See bubonic plague.birth control pill See oral contraceptive. black eye Bruising of the eyelid and/or the area around the eye as a result of trauma to the eye.birth defect Any defect present in a baby at birth. Colloquially known as a shiner.Birth defects involve many different tissues, includ-ing the brain, heart, lungs, liver, bones, and intes- black lung disease A disease of the lungs that istinal tract. These defects can occur for many caused by inhaling coal dust, which in some patientsreasons, including genetic conditions and toxic can lead to progressive massive fibrosis of the lungsexposures of the fetus (for example, to alcohol). All and severely impaired lung function. Also known asparents are at risk of having a baby with a birth anthracosis and coal miner’s pneumoconiosis.defect. Birth defects are now the leading cause ofinfant mortality (death) in the US and many other Black Plague See bubonic plague.developed nations. Infrequent, but significant, birthdefects include heart defects, cleft lip and palate, blackhead A familiar term for what is medicallyDown syndrome, and spina bifida. Also known as called an open comedo. A comedo, the primary signcongenital malformation or congenital anomaly. See of acne, consists of a widened hair follicle filled withalso dysmorphology. skin debris, bacteria, and oil called sebum. A black- head has a wide opening to the skin and is cappedbirthmark A discoloration of the skin that may with a blackened mass of skin debris. In contrast, aor may not be raised and is present at birth. Most closed comedo, commonly called a whitehead, hasbirthmarks are harmless. Occasionally a specific an obstructed opening to the skin and may rupturetype of birthmark can be a visible marker for a to cause a low-grade skin inflammatory reaction inmore serious health problem. See also café au lait; the area.port-wine stain. bladder A hollow organ in the lower abdomenbirthrate The number of live births divided by that stores urine. The kidneys filter waste from thethe average population, or by the population at blood and produce urine, which enters the bladdermidyear. Also known as crude birthrate. through two tubes, called ureters. Urine leaves the bladder through another tube, the urethra. Inbisexual 1 An individual who engages in both women, the urethra is a short tube that opens just inheterosexual and homosexual sexual relations. front of the vagina. In men, it is longer, passingBisexual can also refer to the corresponding through the prostate gland and then the penis. Alsolifestyle. 2 In physical biology, bisexual refers to known as urinary bladder and vesical.an individual who was born with gonadal tissue ofboth sexes (that is, both testicular and ovarian tis- bladder, overactive A condition in which sud-sue). Also known as true hermaphrodite. den involuntary contractions of the muscular wall of the bladder cause urinary urgency, immediate andbisphosphonate A class of drugs used to unstoppable needs to urinate. Overactive bladder isstrengthen bone. Bisphosphonates are used to treat a form of urinary incontinence (the unintentionalosteoporosis and the bone pain from diseases such loss of urine) and is relatively common, particularlyas metastatic breast cancer, multiple myeloma, and in older adults. Treatment may include pelvic mus-Paget’s disease. Bone is in a constant state of cle strengthening, behavioral therapy, and medica-remodeling, whereby new bone is laid down by cells tions. Also called urge incontinence.called osteoblasts, while old bone is removed bycells called osteoclasts. Bisphosphonates inhibit bladder cancer A common form of cancer thatbone removal (resorption) by the osteoclasts. The begins in the lining of the bladder. The most com-bisphosphonates include Fosamax (alendronate), mon warning sign is blood in the urine. SymptomsActonel (risedronate), Boniva (ibandronate), and include pain during urination, frequent urination,Reclast (zoledronate). and feeling the need to urinate without results. A diagnosis of bladder cancer is supported by findingsbite In dental terms, how well the teeth fit in the medical history, physical examination, exam-together (occlude) in the mouth. ination of the urine, and intravenous pyelogram
49 blepharitis(IVP). Confirmation of the diagnosis requires a bladder pain Pain from the urinary bladder.biopsy, usually using a cystoscope. The bladder is Among the symptoms of bladder infection are feel-lined with cells called transitional cells and squa- ings of pain, pressure, and tenderness around themous cells. A tumor may grow through the lining bladder, pelvis, and perineum (the area between theinto the muscular wall of the bladder and extend anus and vagina or anus and scrotum), which mayinto nearby organs such as the uterus or vagina (in increase as the bladder fills and decrease as it emp-women) or the prostate gland (in men). When blad- ties; decreased bladder capacity; an urgent need toder cancer spreads beyond the bladder, the malig- urinate; painful sexual intercourse; and, in men,nant cells are frequently found in nearby lymph discomfort or pain in the penis and scrotum.nodes and may have spread to other lymph nodes orother places, including the lungs, liver, or bones. Blalock-Taussig operation A pioneering oper-Risk factors for bladder cancer include age over 40 ation to treat children born with the heart malfor-years, race (Caucasians are at twice the risk of mation tetralogy of Fallot named for the US surgeonAfrican-Americans and Hispanic-Americans, with Alfred Blalock and the US pediatric cardiologistAsian-Americans at least risk), gender (men are two Helen B. Taussig.to three times more likely to get bladder cancer),family history of bladder cancer, use of tobacco blast An immature blood cell.(which is a major risk factor), occupational expo-sures (for example, workers in the rubber, chemi- blast crisis A phase of advanced leukemia, usu-cal, and leather industries, hairdressers, ally chronic myelogenous leukemia (CML), inmachinists, metal workers, printers, painters, textile which the number of immature, abnormal whiteworkers, and truck drivers), and prior treatment blood cells (blasts) in the bone marrow and bloodwith cyclophosphamide or arsenic exposure. is extremely high. Also known as the blast phase.Treatment depends on the growth, size, and location See also leukemia.of the tumor. Surgical operations are commonlyneeded. Chemotherapy, biological therapy, or radio- blastoma A tumor thought to arise in embryonictherapy may also be used. tissue. This term is commonly used as part of the name for a tumor, as in glioblastoma and medul-bladder infection Infection of the urinary blad- loblastoma (types of brain tumors), hepatoblas-der. Some people are at greater risk for bladder toma (a liver tumor), nephroblastoma (a Wilmsinfections and other urinary tract infections (UTIs) tumor of the kidney), neuroblastoma (a childhoodthan others. Women are at greater risk than men; tumor of neural origin), osteoblastoma (a boneone woman in five develops a UTI during her life- tumor), and retinoblastoma (a tumor of the retinatime. Not everyone with a UTI has symptoms. in the eye).Common symptoms include a frequent urge to uri-nate and a painful burning when urinating. bleb See blister.Underlying conditions that impair the normal uri- bleeding Hemorrhaging. Losing blood, typicallynary flow can lead to more complicated UTIs. Also because of injury to blood vessels. With simpleknown as bacterial cystitis. See also bladder pain. bleeding, cleaning the site of injury and applyingbladder inflammation Inflammation of the uri- mild pressure or a bandage is sufficient treatment. Ifnary bladder. Also called cystitis. Can be due to bleeding is caused by injury to a major blood vessel,infection from bacteria that ascend the urethra to emergency care is necessary. Spontaneous bleedingthe bladder or for unknown reasons, such as with in the skin can represent a serious underlying illnessinterstitial cystitis. Symptoms include a frequent and requires medical evaluation. Menstrual bleedingneed to urinate, often accompanied by a burning involves the normal expulsion of uterine tissue. Seesensation. As bladder inflammation progresses, also hemorrhage; menstruation.blood may be observed in the urine and the patient blepharitis Inflammation of the eyelids.may suffer cramps after urination. In young chil- Blepharitis occurs in two forms, anterior and poste-dren, attempts to avoid the pain of cystitis can be a rior. Anterior blepharitis affects the outside front ofcause for daytime wetting (enuresis). Treatment the eyelid, where the eyelashes are attached. Theincludes avoiding irritants, such as perfumed soaps, two most common causes of anterior blepharitis arenear the urethral opening; increased fluid intake; bacteria (Staphylococcus) and scalp dandruff.and, for infectious cystitis, antibiotics. Untreated Posterior blepharitis affects the inner eyelid (thebladder inflammation can lead to scarring and the moist part that makes contact with the eye) and isformation of stones when urine is retained for long caused by problems with the oil (meibomian)periods of time to avoid painful urination. glands in this part of the eyelid. Two skin disorders can cause this form of blepharitis: rosacea and seb- orrheic dermatitis.
blepharospasm 50blepharospasm The involuntary, forcible clo- Bloch-Sulzberger syndrome See incontinen-sure of the eyelids. The first symptoms may be tia pigmenti.uncontrollable blinking. Only one eye may beaffected initially, but eventually both eyes are usually blocker, beta See beta blocker.involved. The spasms may leave the eyelids com-pletely closed, causing functional blindness even blood The red fluid in the body that containsthough the eyes and vision are normal. white and red blood cells, platelets, proteins, andBlepharospasm is a form of focal dystonia. other elements. Blood is transported throughout the body by the circulatory system. Blood flows in twoblighted ovum A fertilized ovum (egg) that did directions: away from the heart (arterial blood) andnot develop or whose development ceased at an toward the heart (venous blood). Arterial blood hasearly stage, before 6 or 7 weeks of gestation. On the a high concentration of oxygen and nutrients forultrasound examination of a blighted ovum, only the body tissues, and venous blood is the means bygestational sac that normally surrounds the embryo which carbon dioxide is transported to the lungs forcan be seen. There is usually no embryo inside the removal from the body. See also blood cell.gestational sac. A blighted ovum is a form of earlyspontaneous abortion (miscarriage). blood cell One of several different types of cells that make up the blood. The red blood cells (ery-blind Unable to see. See also blindness. throcytes) contain hemoglobin, which carries oxy- gen in the blood. The white blood cells (leukocytes)blinded study A clinical trial of drugs in which are a blood-borne part of the immune system. Thethe test participants do not know whether they are platelets help blood to clot. Together, these threereceiving the product being tested or a placebo types of cells make up about half of the volume of(dummy). This blinding is intended to ensure that blood. The remainder is made up of plasma. Seethe study results are not affected by the power of also erythrocyte; leukocyte; plasma; platelet.suggestion (the placebo effect). See also double-blinded study. blood clot A mass of coagulated blood. A blood clot can block a major blood vessel, causing strokeblindness Loss of useful sight. Blindness can be or other problems.temporary or permanent, and there are manycauses of blindness. Damage to any portion of the blood clot, estrogen-associated A blood cloteye, the optic nerve, or the area of the brain that is associated with estrogen therapy. Blood clots areresponsible for vision can lead to blindness. Also occasional but serious side effects of estrogen ther-known as visually handicapped, visually impaired, apy. They occur most frequently with high doses ofand visually challenged. See also blindness, legal. estrogen. Cigarette smokers on estrogen therapy are at a higher risk for blood clots than nonsmokersblindness, legal A degree of blindness that enti- are. Therefore, patients requiring estrogen therapytles a person to certain benefits according to the law. are strongly encouraged to quit smoking. See alsoThe definition of legal blindness varies from country estrogen; estrogen replacement therapy.to country. In the US, the definition of legal blindnessthat is used to determine eligibility for government blood coagulation The aggregation of blooddisability benefits is as follows: 1 visual acuity of platelets and other blood elements to form a semi-20/200 or worse in the better eye with corrective solid clot. Coagulation occurs under the influencelenses (20/200 means that a person must be at 20 of the clotting factors fibrinogen, prothrombin, andfeet from an eye chart to see what a person with nor- thrombin, which are normally activated in responsemal vision can see at 200 feet); or 2 visual field to injury. Working together, these substancesrestriction to 20 degrees diameter or less (tunnel thicken the blood and produce fibrin, a substancevision) in the better eye. Note that these criteria do that closes off the wound. When blood coagulatesnot necessarily indicate a person’s ability to function. abnormally, dangerous blood clots can enter the bloodstream.blindness, night See nyctanopia. blood conservation Actions taken during med-blindness, river See river blindness. ical treatment and surgery to limit the amount of donor blood needed.blister A collection of fluid underneath the toplayer of skin (epidermis). There are many causes of blood count, complete See CBC.blisters, including burns, friction forces, and dis-eases of the skin. Also known as bleb and bulla. blood culture A test that is designed to detect microorganisms, such as bacteria and fungi, in
51 bloody showblood. A sample of blood obtained using a sterile blood pressure cuff is used to measure pressure.technique is placed in a culture medium and incu- See also hypertension; hypotension; sphygmo-bated in a controlled environment. If microorgan- manometer.isms grow, their type can be identified, and they canbe tested against different antibiotics for proper blood pressure, high See hypertension.treatment of the infection. Because microorganismsmay be only intermittently present in blood, a series blood pressure, low See hypotension.of blood cultures is often done before the result isconsidered negative. See also bacteremia; sepsis; blood sugar, high See hyperglycemia.septicemia. blood sugar, low See hypoglycemia.blood group An inherited feature on the surfaceof the red blood cells. A series of related blood types blood test A test that requires a sample of blood.constitutes a blood group system, such as the Rh or Some blood tests require only a finger stick, andABO system. The frequencies of the ABO and Rh others require a venipuncture (blood taken from ablood types vary from population to population. In vein) or blood withdrawn from an artery.the US, the most common type is O+ (meaning O in blood thinner An anticoagulant agent; a medica-the ABO system and positive in the Rh system), which tion that works against coagulating process ofis present in 37.4 percent of the population. The fre- blood.quencies in the US (in descending order) are O+(37.4 percent), A+ (35.7 percent), B+ (8.5 per- blood titer A blood test that tests for the level, orcent), O- (6.6 percent), A- (6.3 percent), AB+ (3.4 amount (titer), of something in the blood. Forpercent), B- (1.5 percent), and AB- (0.6 percent). example, a strep titer looks for the level of strepto- coccus antibodies in the blood.blood group, ABO See ABO blood group. blood transfusion The transfer of blood orblood in the urine Blood that appears in theurine. Also known as hematuria. Gross hematuria blood components from one person (the donor)refers to blood that is so plentiful in the urine that into the bloodstream of another person (the recipi-the blood is visible with just the naked eye. ent). Blood transfusion may be done as a lifesavingMicrohematuria refers to blood in urine that is visi- maneuver to replace blood cells or blood productsble only under a microscope; there is so little blood lost through bleeding or due to depression of thethat it cannot be seen without magnification. bone marrow. Transfusion of one’s own bloodHematuria, whether gross or microscopic, is abnor- (autologous) is the safest method but requiresmal and should be further investigated. It may or may advanced planning, and not all patients are eligiblenot be accompanied by pain. Painful hematuria can for it. Directed donor blood allows the patient tobe caused by a number of disorders, including infec- receive blood from known donors. Volunteer donortions and stones in the urinary tract. Painless hema- blood is usually most readily available and, whenturia can also be due to a large number of causes, properly tested, has a low risk of side effects.including cancer. blood urea nitrogen A measure of the ureablood marker A sign of a disease or condition level in blood. Abbreviated BUN. Diseases that com-that can be isolated from a blood sample. For exam- promise the function of the kidney frequently lead tople, the monoclonal antibody D8/17 is a diagnostic increased BUN levels.sign of pediatric autoimmune disorders associated blood, urinary See blood in the urine.with streptococcus. blood–brain barrier A protective network ofblood poisoning A bacterial infection of the blood vessels and cells that filters blood flowing toblood. See also bacteremia; sepsis; septicemia. the brain. The blood–brain barrier normally pre- vents infectious agents and foreign substances fromblood pressure The pressure of the bloodwithin the arteries. Blood pressure is produced pri- getting into the brain. Medications designed to workmarily by the contraction of the heart muscle. The within the brain and spinal fluid must cross thetraditional measurement of blood pressure is blood–brain barrier to be effective.recorded by two numbers. The first number (the bloody nose See nosebleed.systolic pressure) is measured after the heart con-tracts, and it is the higher number. The second num- bloody show Literally, the appearance of blood,ber (the diastolic pressure) is measured before a classic sign of impending labor. The bloody showthe heart contracts, and it is the lower number. A
bloody sputum 52consists of blood-tinged mucus created by extrusion body dysmorphic disorder A psychiatric disor-and passage of the mucous plug that filled the cervical der characterized by excessive preoccupation withcanal during pregnancy. imagined defects in physical appearance. It is classi- fied as an anxiety disorder, and it is believed to be abloody sputum Coughed up blood or bloody variant of obsessive-compulsive disorder. Also knownmucus. Bloody sputum can be caused by infection in as somatoform disorder and dysmorphophobia.the lungs and airways, such as acute bronchitis orpneumonia, or cancer. Whenever bloody sputum is body mass index A key index for relating weightpresent and cannot be attributed to a curable infec- to height. Abbreviated BMI. BMI is a person’s weighttious condition, a complete lung evaluation is war- in kilograms (kg) divided by his or her height inranted, including bronchoscopy, to be certain cancer meters squared. The National Institutes of Healthis not present. Also known as hemoptysis. (NIH) now defines normal weight, overweight, and obesity according to BMI rather than the traditionalblot, Western A technique in molecular biology height/weight charts. Overweight is a BMI of 27.3 orthat is used to separate and identify proteins. It is more for women and 27.8 or more for men. Obesitycalled a Western blot merely because it is similar to is a BMI of 30 or more for either sex (about 30a Southern blot, which was named after its inventor, pounds overweight). A very muscular person mightthe British biologist M.E. Southern. For example, have a high BMI without health risks.the Western blot assay method is commonly used todiagnose Lyme disease. body surface area The total suface area of the human body. The BSA is used in many measure-Blount disease See tibia vara. ments in medicine, including the calculation of drug dosages and the amount of fluids to be administeredblue baby See cyanosis. intravenously. Abbreviated BSA.blush Redness of the skin as a result of dilated body type A somewhat old-fashioned term usedcapillaries, typically over the cheeks or neck. to classify the human shape into three primaryBlushing is an involuntary response of the nervous types: ectomorphic, mesomorphic, or endomor-system that leads to widening of the capillaries in phic.the involved skin. A blush is temporary, and it maybe brought on by excitement, exercise, fever, or bodywork Any of a number of therapeutic orembarrassment. Also known as flush. simply relaxing practices that involve the manipula- tion, massage, or regimented movement of bodyBM Physician’s shorthand for black male. parts. Examples include massage, craniosacral ther- apy, and Pilates. Bodywork may be used as anBMD See bone mineral density. adjunct to medical treatment, or it may be pre- scribed as a form of physical therapy for certainBMI Body mass index. conditions.BMJ British Medical Journal, one of the major boil A skin abscess that forms at a hair folliclegeneral medical journals in the world. BMJ states infected with pus-forming bacteria. The main treat-that it “aims to help doctors everywhere practice ments include hot packs and draining (lancing) thebetter medicine and to influence the debate on boil when it is soft. Antibiotics are usually not veryhealth.” helpful in treating boils. A person who has a fever or long-term illness, such as cancer or diabetes, or isBNP See B-type natriuretic peptide. taking medications that suppress the immune sys-board certified In medicine, a description for a tem should contact a health care practitioner onphysician who has taken and passed a medical spe- developing a boil. Also known as furuncle.cialty examination by one of several recognizedboards of specialists. Before obtaining board certi- bone The hard connective tissue that forms the skeleton of the body. It is composed chiefly of colla-fication, the physician must become board eligible. gen fibers that contain calcium phosphate and cal-board eligible In medicine, a description for a cium carbonate. Bones also serve as a storage areaphysician who has completed the requirements for for calcium, playing a large role in calcium balanceadmission to a medical specialty board examination in the blood. The 206 bones in the human bodybut has not passed that examination. For example, a serve a wide variety of purposes. They support andphysician must have 3 years of training in an protect internal organs; for example, the ribs pro-approved pediatric residency to be eligible for cer- tect the lungs. Muscles pull against bones to maketification by the American Board of Pediatrics. the body move. See also bone marrow.
53 bone scanbone, breast See sternum. bone density See bone mineral density.bone, cuboid The outer bone in the instep of the bone marrow The soft blood-forming tissue thatfoot. It is called the cuboid bone because it is fills the cavities of bones and contains fat and imma-shaped like a cube. The cuboid bone is jointed in ture and mature blood cells, including white bloodback with the heel bone (calcaneus) and in front cells, red blood cells, and platelets. Diseases orwith the bones just behind the fourth and fifth toes drugs that affect the bone marrow can affect the(metatarsals). total counts of these cells.bone, heel See calcaneus. bone marrow aspiration The removal of a small amount of liquid bone marrow through a nee-bone, sesamoid A little bone that is embedded dle. The needle is placed through the top layer ofin a joint capsule or tendon; for example, the bone, and a liquid sample containing bone marrowkneecap (patella). cells is obtained through the needle by sucking (aspirating) it into a syringe. The suction causesbone, shin The larger of the two bones in the pain for a few moments. Bone marrow aspiration islower leg. The shin bone is anatomically known as done to diagnose and follow the progress of variousthe tibia. Its smaller companion is the fibula. conditions, including anemia and cancer, and to obtain marrow for transplantation.bone cancer A malignancy of bone. Primarybone cancer (cancer that begins in bone) is rare, bone marrow biopsy The removal of a samplebut it is not unusual for cancers to metastasize of bone marrow and a small amount of bone(spread) to bone from other parts of the body, such through a large needle. Two samples are taken. Theas the breast, lung, and prostate. The most common first is bone marrow by aspiration (suction with atype of primary bone cancer is osteosarcoma, which syringe). The second is a core biopsy to obtain bonedevelops in new tissue in growing bones. Another marrow along with bone fibers. After the needle istype of cancer, chondrosarcoma, arises in cartilage. removed, this solid sample is pushed out of the nee-Ewing’s sarcoma begins in immature nerve tissue in dle with a wire. Both samples are examined under abone marrow. Osteosarcoma and Ewing’s sarcoma microscope to examine the cells and the architec-tend to occur in children and adolescents, and ture of the bone marrow.chondrosarcoma occurs most often in adults. Painis the most frequent symptom of primary and bone marrow transplant A procedure in whichmetastatic cancer in bone. Bone cancer can also diseased or damaged bone marrow is replaced withinterfere with normal movements and can weaken healthy bone marrow. The bone marrow to bethe bones, leading to fractures. Diagnosis of bone replaced may be deliberately destroyed by highcancer is supported by findings of the medical his- doses of chemotherapy and/or radiation therapy.tory and examination, blood tests (including meas- Replacement marrow may come from another per-uring the level of the enzyme for the enzyme alkaline son, or the patient’s own marrow may be removedphosphatase), and X-ray studies, and it is confirmed and stored before treatment for later use. Whenby a biopsy. Treatment depends on the type, loca- marrow from an unrelated donor is used, the pro-tion, size, and extent of the tumor. Surgery is often cedure is referred to as allogeneic. If the marrow isthe primary treatment. Although amputation of a from an identical twin, it is termed syngeneic.limb is sometimes necessary for primary bone can- Autologous bone marrow transplantation uses thecer, chemotherapy has made limb-sparing surgery patient’s own marrow. Abbreviated BMT. See alsopossible in many cases. Radiation may also be used. transplant.bone cyst, aneurysmal A benign lesion in a bone mineral density Also known as BMD andbone that contains connective tissue and blood bone density. A measure of bone density, reflectinginside a thin bony shell. Aneurysmal bone cysts act the strength of bones as represented by calcium con-like tumors and expand the bone, and they typically tent. The BMD test detects osteopenia (mild boneoccur in the second decade of life. They can affect loss, usually without symptoms) and osteoporosisany bone in the arms, legs, trunk, or skull. (more severe bone loss, which may cause symp- toms). See also osteopenia; osteoporosis.bone cyst, simple A solitary fluid-filled cavity(cyst) in a bone, usually in the shaft of a long bone, bone scan A nuclear medicine technique for cre-especially the humerus, in a child. A simple bone ating images of bones on a computer screen orcyst can cause pain in or near the bone. Also known on film. A small amount of radioactive materialas unicameral bone cyst and solitary bone cyst. is injected into a vein and travels through the bloodstream. It collects in the bones, especially in
bones, appendicular 54abnormal areas of the bones, and is detected by an bones of the trunk The 51 trunk bones consistinstrument called a scanner. Bone scans are used of 26 vertebrae, 24 ribs, and the sternum. The 26for the detection and monitoring of disorders that vertebrae comprise 7 cervical, 12 thoracic, and 5affect the bones, including Paget disease, cancer, lumbar vertebrae, plus the sacrum and the coccyx.infections, and fractures. Bone scanning is also The 24 ribs comprise 14 true ribs, 6 false ribs, andhelpful in evaluating and measuring the activity of 4 floating ribs. The sternum is the breastbone. Alongcertain joint diseases. with the bones of the head, also known as axial bones.bones, appendicular See bones of the arm,wrist, and hand. bony syndactyly A condition in which the bones of the fingers or toes are joined together. Bony syn-bones, axial See bones of the head. dactyly is not the same as cutaneous syndactyly, which only involves webbing of the skin between thebones, lower extremity See bones of the leg, digits.ankle, and foot. bony tarsus A structure that is made up of sevenbones of the arm, wrist, and hand There are bones situated between the bones of the lower leg64 bones in the upper extremities. They consist of and the metatarsus bones of the feet. The seven10 shoulder and arm, 16 wrist, and 38 hand bones. bones of the bony tarsus are the calcaneus, talusThe 10 shoulder and arm bones are the clavicle, (astragalus), cuboid, and navicular (scaphoid),scapula, humerus, radius, and ulna on each side. plus the first, second, and third cuneiform bones.The 16 wrist bones are the scaphoid, lunate, tri- The bony tarsus contributes to the broad, flat frame-quetrum, pisiform, trapezium, trapezoid, capitate, work of the foot.and hamate on each side. The 38 hand bones arethe 10 metacarpal bones and 28 finger bones (pha- booster shot An additional dose of a vaccinelanges). Also known as appendicular bones. needed periodically to “boost” the immune system. For example, a booster shot of the tetanus and diph-bones of the head There are 29 bones in the theria (Td) vaccine is recommended for adultshuman head. They include 8 cranial bones, 14 facial every 10 years.bones, the hyoid bone, and 6 ear (auditory) bones.The 8 cranial bones are the frontal, 2 parietal, borborygmus A gurgling, rumbling, or squeak-occipital, 2 temporal, sphenoid, and ethmoid ing noise from the abdomen that is caused by thebones. The 14 facial bones are the 2 maxilla, the movement of gas through the bowels. Also known asmandible, 2 zygoma, 2 lacrimal, 2 nasal, 2 stomach rumbling. The plural is borborygmi.turbinate, vomer, and 2 palate bones. The hyoidbone is the horseshoe-shaped bone at the base of borderline personality disorder A personalitythe tongue. The 6 small auditory bones (ossicles) type characterized by difficulty forming and keepingare the malleus, incus, and stapes in each ear. Along stable relationships, highly emotional or aggressivewith the bones of the trunk, also known as axial behavior, impulsivity, and rapid shifts in values, self-bones. See also bones of the trunk. image, mood, and behavior.bones of the leg, ankle, and foot There are 62 Bornholm disease A viral infection that is mostlower extremity bones. They consist of 10 hip and commonly caused by an enterovirus calledleg, 14 ankle, and 38 foot bones. The 10 hip and leg Coxsackie B. Symptoms include fever, intensebones are the innominate, or hip, bone (which is a abdominal and chest pain, and headache. The chestfusion of the ilium, ischium, and pubis), and the pain is caused by inflammation of the tissue liningfemur, tibia, fibula, and patella (kneecap) on each the lungs, and it is typically worsened by breathing orside. The 14 ankle bones are the talus, calcaneus coughing. The illness usually lasts from 3 to 14 days.(heel bone), navicular, cuboid, internal cuneiform, Also known as epidemic myalgia and pleurodynia.middle cuneiform, and external cuneiform on eachside. The 38 foot bones are the 10 metatarsals and botox A highly purified preparation of botulinum28 toe bones (phalanges). toxin A, a toxin produced by the bacterium Clostridium botulinum. Botox is injected, in verybones of the skeleton The human body has 206 small amounts, into specific muscles, as a treatment.bones. These consist of 80 axial (head and trunk) It acts by blocking the transmission of nervebones and 126 appendicular (upper and lower impulses to muscles and so paralyzes (relaxes) theextremity) bones. See also bones of the arm, wrist, muscles. Botox treatment has found a growing num-and hand; bones of the head; bones of the leg, ber of uses from easing muscle spasms (as, forankle, and foot; bones of the trunk.
55 brachial arteryexample, in spastic cerebral palsy) to its increasingly ited to the intestine or associated with diseasewidespread cosmetic use in flattening wrinkles. involving the skin, joints, spine, liver, eyes, and other organs. The cause is not always known,bottlefeeding The practice of feeding an infant a although it can be caused or made worse by infec-substitute for breast milk. Pediatricians generally tion. Symptoms include abdominal pain and diar-advise exclusively breastfeeding (that is, breastfeed- rhea. Symptoms tend to wax and wane, and longing with no supplementary formula) for all full- remissions and even spontaneous resolution ofterm, healthy infants for the first 6 months of life. symptoms are well known. Although people of anyHowever, many infants are bottlefed today, at least in age can be affected, IBD is most common in youngpart. For infants to achieve normal growth and adults. Treatment involves dietary changes, the usemaintain normal health, infant formulas must of medicines, and sometimes surgery, depending oninclude proper amounts of water, carbohydrate, the type and course of the disease under care.protein, fat, vitamins, and minerals. Effective therapy exists for the majority of cases. Narcotics, codeine, and antidiarrheal medicationsbotulinum toxin A toxin produced by the bac- should be avoided during severe episodes of IBDterium Clostridium botulinum, which is the most because they may cause dangerous colon swellingpoisonous biological substance known. Botulinum (toxic megacolon). See also Crohn’s disease; coli-toxin is toxic to nerves. It binds to the nerve ending tis, ulcerative.at the point where the nerve joins a muscle, block-ing the release by the nerve of the chemical acetyl- bowel disorders and fiber High-fiber dietscholine (the principal neurotransmitter at the help delay the progression of and number of boutsneuromuscular junction), preventing the muscle with diverticulosis. In many cases, high-fiber dietsfrom contracting. The result is weakness and paral- help reduce the symptoms of irritable bowel syn-ysis of the muscle. Purified botulinum toxin A was drome (IBS). It is generally accepted that a dietthe first bacterial toxin to be used as a medicine. It high in fiber is protective or at least reduces theis marketed under the trade name Botox. See also incidence of colon polyps and colon cancer.botox; botulism. Bowen’s disease See cancer, skin.botulism An uncommon but potentially very seri-ous type of food poisoning that produces paralysis bowlegs A condition in which the legs curve out,of muscles, from a nerve toxin called botulinum leaving a gap between the knees, after infancy.toxin that is produced by the bacteria Clostridium Bowlegs can be corrected with surgery or casting.botulinum. There are various types of botulism, Also known as genu varum and tibia vara.including food-borne, wound, infant intestinal, andadult intestinal botulism. The symptoms of botulism BP In general medicine, blood pressure. On acan range from mild, including transient nausea medical chart, you might see “BP90/60 T98.6and vomiting, to severe that progress to heart and Ht60/reg R15,” which signifies that the blood pres-lung failure and death. Food-borne botulism occurs sure (BP) is 90/60 mm Hg, the temperature (T) istypically in unrefrigerated or poorly refrigerated 98.6° Fahrenheit, the heart rate (Ht) is 60 beats perfoods and foods without preservatives, especially minute and regular, and respirations are occurringuncooked or half-cooked meats. It can be pre- at 15 per minute.vented by careful use of refrigeration and preserva-tive techniques, and the toxin can be destroyed with BPH Benign prostatic hyperplasia, benign prosta-heat. Clostridium botulin and botulinum toxin tic hypertrophy.might, it is feared, be misused as agents of bioter-rorism. See also bioterrorism; food poisoning; brace, foot drop See ankle-foot orthosis.botox. braces, dental Devices used by orthodontists toboutonneuse See typhus, African tick. move the position teeth or adjust underlying bone. Temporomandibular joint (TMJ) problems can alsobowel The small and large intestine. sometimes be corrected with dental braces. Teeth can be moved by removable appliances or by fixedbowel disease, inflammatory A group of braces. If there is crowding of teeth, some teeth maychronic intestinal diseases characterized by inflam- need to be extracted before braces are applied.mation of the bowel (the small and large intestine). Retainers may be necessary long after dental bracesAbbreviated IBD. The most common types of IBD are placed, especially in orthodontic treatment ofare ulcerative colitis and Crohn’s disease. The por- adults.tion of the intestine that is affected becomes irritatedand swollen, and ulcers may form. IBD can be lim- brachial artery The artery that runs from the shoulder down to the elbow. See also brachial vein.
brachial plexus 56brachial plexus A bundle of nerves that begins factors, including the age of the individual and thein the back of the base of the neck and extends degree of exertion.through the armpit. It is formed by the union of por-tions of the fifth through eighth cervical spinal Braille A system of raised-dot writing for thenerves and the first thoracic spinal nerve. Damage blind in which each letter is represented as a raisedto the brachial plexus can affect nerves responsible pattern that can be read by touching it with the fin-for muscle function and sensation of the arm and gers. In Braille, dot patterns are assigned to letterschest. of the alphabet, punctuation marks, and other sym- bols. Braille was devised by Louis Braille.brachial vein A vein that accompanies thebrachial artery between the shoulder and the elbow. brain The portion of the central nervous systemThe route of the brachial vein is from the elbow up that is located within the skull. It functions as a pri-to the shoulder. See also brachial artery. mary receiver, organizer, and distributor of infor- mation for the body. It has a right half and a left half,brachy- Prefix indicating short, as in brachy- each of which is called a hemisphere.cephaly (short head) and brachydactyly (short fin-gers and toes). brain, fornix of the One of a pair of arching fibrous bands in the brain that connects the twobrachycephaly A condition in which the head is lobes of the cerebrum.unusually short in diameter from front to back.Brachycephaly is frequently a feature in congenital brain, water on the See hydrocephalus.malformation syndromes, including Down syn-drome (trisomy 21). brain aneurysm See aneurysm, brain.brachydactyly A condition in which the fingers brain cancer A malignant growth of the brain.and toes are short and stubby. Brachydactyly is a See also brain tumor.common finding in malformation sydromes, such asDown syndrome (trisomy 21). brain death The permanent, irreversible cessa- tion of all brain functions. Brain death is not thebrachytherapy Radiation treatment given by same thing as a coma or vegetative state. The pres-placing radioactive material directly in or near the ence of brain death is legally synonymous with deathtarget, which is often a tumor. Brachytherapy for itself in most US states.prostate cancer, for example, is also called intersti-tial radiation therapy or seed implantation. In brain freeze A headache that occurs when onebrachytherapy for prostate cancer, radioactive seeds puts ice, a cold food, or a chilled beverage in theare implanted in the prostate. The seeds might be mouth, chilling the roof of the mouth. Ice cream istitanium-encased pellets that contain the radioiso- by far the most frequent offender. Brain freeze istope iodine-125. characterized by a stabbing, aching pain that begins a few seconds after ingestion of something cold. Thebrady- Prefix indicating slow, as in bradycardia pain peaks in 30 to 60 seconds. No treatment is(slow heart rate), bradykinesia (slow movement), required. Also known as an ice cream headache.and bradyphrenia (slow thought processes). brain malleability See brain plasticity.bradycardia A slow heart rate, usually defined asless than 60 beats per minute. brain plasticity The phenomenon of change and learning in the adult brain. Also known as brainbradykinesia Slow movement. Bradykinesia is malleability.often associated with an impaired ability to adjustthe body’s position. Bradykinesia can be a symptom brain stem The stem-like part of the base of theof nervous system disorders, particularly brain that is connected to the spinal cord. The brainParkinson’s disease, or a side effect of medications. stem controls the flow of messages between the brain and the rest of the body, and it also controlsbradyphrenia A slow thought process. basic body functions such as breathing, swallowing,Bradyphrenia can be a side effect of certain psychi- heart rate, blood pressure, consciousness, andatric medications. whether one is awake or sleepy. The brain stem con- sists of the midbrain, pons, and medulla oblongata.bradypnea Abnormally slow breathing. A respira-tory rate that is too slow. The normal rate of respira- brain stem glioma A type of brain tumor thattions (breaths per minute) depends on a number of involves the glial cells.
57 breast, infiltrating lobular carcinoma of thebrain tumor A benign or malignant growth in the BRCA1 and BRCA2 are responsible for about halfbrain. Primary brain tumors initially form in brain the cases of inherited breast cancer, especially thosetissue. Secondary brain tumors are cancers that that occur in relatively young women. From thehave spread (metastasized) to the brain tissue from words breast and cancer. See also breast cancertissue elsewhere in the body. Brain tumors can susceptibility gene.occur in people of any age. BRCA2 A tumor suppressor gene that normallybrain ventricle One of the communicating cavi- acts to restrain the growth of cells. Mutations ofties within the brain. There are four ventricles: two BRCA2, like those of BRCA1, are responsible mainlylateral ventricles, the third ventricle, and the fourth for hereditary breast cancer. They seldom appear toventricle. The lateral ventricles are in the cerebral be involved in sporadic, noninherited breast can-hemispheres. Each lateral ventricle consists of a tri- cer—the 95 percent of breast cancer that does notangular central body and four horns. The lateral run in families. Both BRCA1 and BRCA2 are large,ventricles communicate with the third ventricle complex genes. From the words breast and cancer.through the interventricular foramen (opening). See also breast cancer susceptibility gene.The third ventricle is a median (midline) cavity inthe brain, bounded by the thalamus and hypothala- breadbasket A popular term for the stomach.mus on either side. In front, the third ventricle com-municates with the lateral ventricles, and in back it breakbone fever See dengue fever.communicates with the aqueduct of the midbrain(the aqueduct of Sylvius). The fourth ventricle is the breast The front of the chest or the mammarymost inferior of the four ventricles of the brain. It gland. The mammary gland is a milk-producingextends from the aqueduct of the midbrain to the gland that is largely composed of fat. Within thecentral canal of the upper end of the spinal cord, mammary gland are sac-like structures called lob-with which it communicates by the two foramina ules, which produce the milk, as well as a complex(openings) of Luschka and the foramen of network of branching ducts. These ducts exit fromMagendie. The ventricles are filled with cere- the lobules at the nipple. The lobules and ducts arebrospinal fluid, which is formed by structures, supported in the breast by surrounding fatty tissuecalled choroid plexuses, that are located in the walls and ligaments. The breast contains blood vesselsand roofs of the ventricles. and lymphatics, but no muscles. The lymphatics are thin channels similar to blood vessels; they do notbranchial cleft cyst A cavity that is a remnant carry blood, but they collect and carry tissue fluid,from embryologic development and is still present which ultimately reenters the bloodstream. Breastat birth in one side of the neck, just in front of the tissue fluid drains through the lymphatics into thelarge angulated muscle on either side (the stern- lymph nodes located in the armpit and behind theocleidomastoid muscle). The cyst may not be rec- breastbone (sternum). The appearance of the nor-ognized until adolescence, when it enlarges its oval mal female breast differs greatly among individualsshape. Sometimes a branchial cleft cyst develops a and at different times during a woman’s life: before,sinus or drainage pathway to the surface of the skin, during, and after adolescence; during pregnancy;from which mucus can be expressed. Total surgical during the menstrual cycle; and after menopause.excision is the treatment of choice. Also known as The nipple of the breast becomes erect because ofbranchial cyst. cold, breastfeeding, and sexual activity. The pig- mented area around the nipple is called the areola.branchial cyst See branchial cleft cyst. See also gland, mammary.Braxton Hicks contraction An irregular con- breast, infiltrating ductal carcinoma of thetraction of the womb (uterus) that occurs toward One of several recognized specific patterns of breastthe middle of a woman’s first pregnancy and earlier, cancer that begins in the cells that form the ducts ofand more intensely, in her subsequent pregnancies. the breast. The most common form of breast can-Braxton Hicks contractions tend to occur during cer, it may appear as a smooth-edged lump in thephysical activity. The uterus tightens for 30 to 60 breast. On physical examination, this lump usuallyseconds, beginning at the top of the uterus, and the feels much harder or firmer than benign lumps incontraction gradually spreads downward before the the breast.uterus relaxes. Braxton Hicks contractions may bequite uncomfortable and sometimes difficult to dis- breast, infiltrating lobular carcinoma of thetinguish from the contractions of true labor. The second most common invasive breast cancer. Infiltrating lobular carcinoma starts in the lobules,BRCA1 A tumor suppressor gene that normally the glands that secrete milk, and then infiltrates sur-acts to restrain the growth of cells. Mutated forms of rounding tissue. Lobular carcinoma can occur in
breast, Paget’s disease of 58more than one site in the breast or in both breasts screening. Most breast cancers are treatable whenat the same time (a bilateral lobular carcinoma). caught early, and survival rates are high. See also breast cancer susceptibility gene; breast cancer,breast, Paget’s disease of The combination of familial; breast, infiltrating ductal carcinoma ofscaly skin on the nipple that resembles eczema and the; breast, infiltrating lobular carcinoma of the;an underlying cancer of the breast. The nipple is mastectomy.inflamed because of the presence of Paget’s cells,large, irregular cells that are almost always associ- breast cancer, familial A form of breast cancerated with cancer in the breast. In Paget’s disease, the that tends to occur in members of the same family. Anipple and areola (the area surrounding the nipple) number of factors have been identified as increasingare typically red, inflamed, and itchy. There may be the risk of breast cancer. One of the strongest is acrusting, bleeding, or ulceration. The nipple may be family history of breast cancer in a relative. About 15inverted (turned inward), and there may be a dis- to 20 percent of women with breast cancer havecharge from the nipple. Paget’s disease of the breast such a family history of the disease, clearly reflectingaccounts for a small but significant minority of all the participation of inherited (genetic) componentsbreast tumors. It usually occurs in women in their in the development of some breast cancers.50s, but it can occur at a later age. It is very rare in Dominant breast cancer susceptibility genes, includ-men. Also called Paget’s disease of the nipple. ing BRCA1 and BRCA2, appear to be responsible for about 5 percent of all breast cancer. See also BRCA1;breast absence See amastia. BRCA2; breast cancer susceptibility gene.breast augmentation Artificial enlargement of breast cancer, male Breast cancer in men. Malethe breasts. Breast augmentation may be done by breast cancer is much less common than breastinsertion of a silicone bag (prosthesis) under the cancer in women. Fewer than 1 percent of personsbreast (submammary) or under the breast and with breast cancer are male. However, breast can-chest muscle (subpectoral), after which the bag is cer is no less dangerous in males than in females.filled with saline solution. This prosthesis expands After the diagnosis of breast cancer is made, thethe breast area to give the appearance of a fuller mortality rates are virtually the same for men andbreast (increased cup size). for women.breast cancer A common form of cancer that breast cancer susceptibility gene An inheritedbegins in the breast. There are many types of breast factor that predisposes an individual to breast can-cancer, and they differ in their capability of spread- cer. Two of these genes, BRCA1 and BRCA2, haveing to other body tissues (metastasis). Breast can- been identified. Several other genes (those for Li-cer can occur in both men and women, although it Fraumeni syndrome, Cowden disease, Muir-Torreis more common in women. Some forms of breast syndrome, and ataxia-telangiectasia) are alsocancer are genetic (inherited), and others are known to predispose women to breast cancer.linked to exposure to cancer-causing substances, However, because all these known breast cancerbut most cases of breast cancer occur for unknown susceptibility genes together do not account forreasons. Risk factors for breast cancer may include more than a minor fraction of breast cancer thatgenetic predisposition, as indicated by a history of clusters in families, it is clear that more breast can-breast cancer in close relatives; overexposure of the cer genes remain to be discovered. See also BRCA1;chest to radiation, smoking, childlessness, induced BRCA2.abortion, obesity and diet, and exposure to carcino-genic substances. Breast cancer is diagnosed with breast implant See breast augmentation.self-examination and physician examination of thebreasts, mammography, ultrasound testing, and breast milk Milk from the breast. Human milkbiopsy. Treatment depends on the type and location contains a balance of nutrients that closely matchesof the breast cancer, as well as the age and health of infant requirements for brain development, growth,the patient. Options may include lumpectomy and a healthy immune system. Human milk also(removal of the small, cancerous area only), contains immunologic agents and other compoundschemotherapy, radiation, and partial or total mas- that act against viruses, bacteria, and parasites.tectomy. The American Cancer Society recommendsthat all women should perform regular breast self- breast reduction Surgical reduction of breastexams and that women should have a baseline size in order to reduce the weight of the breasts andmammogram done between the ages of 35 and 40 relieve symptoms from unusually large, pendulousyears. After age 40, yearly mammograms are rec- breasts. Breast reduction can relieve skin irritationommended. Breast cancer prevention includes diet of the chest, and pain in the back and shoulders.changes, avoiding carcinogens when possible, and Also known as reduction mammaplasty.
59 bronchoscopybreastbone See sternum. Broca area An area of the cerebral motor cortex in the frontal lobe of the brain that is responsible forbreastfeeding The highly recommended prac- speech development. Damage to the Broca area cantice of feeding an infant with the mother’s natural cause speech disorders, including aphasia, apraxia,milk. Breast milk contains vitamins, minerals, and and dyspraxia. See also aphasia; apraxia ofenzymes that aid the baby’s digestion, and immunity speech; dyspraxia of speech.factors in breast milk can help infants fight off infec-tions. Breast milk can be expressed, manually or Broda test See basal temperature.with the assistance of a breast pump, for use whilethe mother is away, or breastfeeding and formula- bronchi The plural of bronchus.feeding can be used together. The activity of breast-feeding has strong benefits for mothers as well as bronchiectasis Permanent abnormal wideninginfants: It encourages the release of hormones that of the bronchi (air tubes that branch deep into theimprove uterine muscle tone, and it may help to lungs). Bronchiectasis can cause recurrent lungprevent breast cancer. The ability of the breast to infections, a disabling cough, shortness of breath,produce milk diminishes soon after childbirth with- and coughing up blood.out the stimulation of breastfeeding. Also known asnursing. See also lactation. bronchiole The tiny branch of air tubes within the lungs that is a continuation of the bronchus. Thebreathing The process of respiration, during bronchioles connect to the alveoli (air sacs).which air is inhaled into the lungs through themouth or nose due to muscle contraction and then bronchiolitis Inflammation of the bronchioles,exhaled due to muscle relaxation. usually due to viral infections.breech The buttocks. bronchitis Inflammation and swelling of the bronchi. Bronchitis can be acute or chronic.breech birth Birth of a baby with the buttocks,rather than the head, emerging first. Breech birth is bronchitis, acute An infection of the bronchi ofmore likely to cause injury to the mother or the recent origin, typically characterized by cough,infant than head-first birth. In many cases a baby in chest discomfort, and production of mucus (spu-the breech position can be turned before delivery by tum). Acute bronchitis is treated with antibiotics.using repeated, gentle massage. bronchitis, chronic Inflammation and swellingBrenner tumor A tumor of the surface of the of the lining of the airways, leading to narrowingovary. Brenner tumors are usually benign, but in and obstruction generally resulting in daily cough.rare cases, they are cancerous. The inflammation stimulates production of mucus, which can cause further blockage of the airways.bridge 1 A set of one or more false teeth that is Obstruction of the airways, especially with mucus,supported by a metal framework and used to increases the likelihood of bacterial lung infection.replace one or more missing teeth. 2 A form of Chronic bronchitis is common in persons who havetreatment that serves as a transition from a previous smoked for extended periods.form of treatment and is followed with anotherform, such as in “bridge therapy.” 3 Tissue that bronchopulmonary dysplasia A chronic lungforms an arc over adjacent tissue(s). For example, disease in infants who received mechanical respira-heart tissue that has formed over a coronary artery, tory support with high oxygenation in the neonatalsometimes physically pinching the artery, is referred period.to as a myocardial bridge. bronchopulmonary segment A subdivision ofBrill-Zinsser disease Reactivation of epidemic one lobe of a lung, based on the connection to thetyphus years after an earlier attack of the disease. segmental bronchus. For example, the right upperRickettsia prowazekii, the agent that causes epi- lobe of the lung has apical, anterior, and posteriordemic typhus, remains viable for many years. When segments.the host’s defenses are down, it can be reactivated.See also rickettsial diseases; typhus, epidemic. bronchoscope A thin, flexible instrument with a lighted viewing tube that is used to visualize the airbrittle bone disease See osteogenesis imper- passages to the lungs.fecta. bronchoscopy A procedure using a broncho-BRM See biological response modifier. scope to diagnose and treat lung conditions and dis- ease. See also bronchoscope.
bronchospasm 60bronchospasm A temporary narrowing of the ing or rubbing together of the teeth. Bruxism canairways in the lung. Bronchospasm causes the injure teeth and cause local pain in the mouth orbreathing difficulties seen in asthma. See also jaw and may contribute to temporomandibular jointasthma. (TMJ) syndrome.bronchospasm, exercise-induced See asthma, BSA See body surface area.exercise-induced. B-type natriuretic peptide A 32-amino-acidbronchus A large air tube that begins at the end polypeptide secreted by the ventricles of the heart inof the trachea and branches into the lungs. The sup- response to excessive stretching of heart muscleporting walls of the bronchus are made up in part of cells. The levels of B-type natriuretic peptide arecartilage. elevated in patients with congestive heart failure, and correlate with both the severity of symptomsBrown’s syndrome An eye abnormality that can and the prognosis. Also known as BNP.present at birth characterized by an inability to ele-vate the eyeball when trying to move the eyeball to bubo An enlarged lymph node that is tender andthe outside. Brown’s syndrome can also be caused painful. Buboes particularly occur in the groin andby other conditions that affect the normal function armpit (the axillae). These swollen glands are seenof the eye muscles, such as nodules from rheuma- in a number of infectious diseases, including gon-toid arthritis or rare tumors in the eye muscle. orrhea, syphilis, tuberculosis, and the eponymous bubonic plague.Brucellosis An infectious disease characterizedby rising and lowering (undulant) fever, sweating, bubonic plague An infectious disease that ismuscle and joint pains, and weakness. Brucellosis caused by the bacterium Yersinia pestis and is trans-is caused by the bacterium Brucella, which can be mitted to humans from infected rats by the orientaltransmitted in unpasteurized milk from cattle, rat flea. It is named for the characteristic feature ofsheep, and goats; cheese made from this unpasteur- buboes (painfully enlarged lymph nodes) in theized milk; and contact with diseased animals. groin, armpits, neck, and elsewhere. Other symp-Antibiotics are used to treat Brucellosis. Also known toms of bubonic plague include headache, fever,as undulant fever. chills, and weakness. Bubonic plague can lead to gangrene (tissue death) of the fingers, toes, andbruise Injury of the soft tissues that results in nose. Also called Black Death and Black Plague.breakage of the local capillaries and leakage of redblood cells. In the skin it can be seen as a reddish- buccal mucosa The inner lining of the cheekspurple discoloration that does not blanch when and lips.pressed. When a bruise fades, it becomes green andbrown, as the body metabolizes the blood cells in bulbourethral gland A pea-sized gland in thethe skin. It is best treated with local application of a male located behind and to the side of the urethracold pack immediately after injury. Also known as that discharges a component of seminal fluid intocontusion. the urethra. There are two bulbourethral glands, one on each side. Also known as the Cowper’sbruit A sound heard over an artery or vascular gland.channel, reflecting turbulence of flow. Most com-monly, a bruit is caused by abnormal narrowing of bulimia An eating disorder characterized byan artery. Listening for a bruit in the neck with a periods of extreme overeating, often interrupted bystethoscope is a simple way to screen for narrowing periods of anorexia. Bulimia is usually accompa-(stenosis) of the carotid artery, which can be a nied by self-induced vomiting or other forms ofresult of cholesterol plaque accumulation. purging, including the use of laxatives, obsessive exercise, or fasting. Bulimia can be life-threateningBrushfield spot A little white spot on the surface due to dehydration, and it can cause permanentof the iris. Brushfield spots are arranged in a ring, damage to the bowels, liver, kidney, teeth, and heart.concentric with the pupil. These spots occur in nor- It also raises a person’s risk of seizures. It ismal children but are far more frequent in those with believed to be closely related to obsessive-compul-Down syndrome. Also called speckled iris. sive disorder. Treatment may include cognitive behavior therapy, dietary and health education, andbruxism Grinding and gnashing of the teeth. antidepressant medication. Also known as bulimiaBruxism is due to clenching of the teeth other than nervosa. See also anorexia nervosa; body dysmor-in chewing and is associated with forceful lateral or phic disorder; obsessive-compulsive disorder.protrusive jaw movements. This results in the grind-
61 bursitis, hipbulla See blister. burn, second degree A burn severe enough to cause blistering of the skin. The pain of a second-bullous Characterized by blistering, such as a degree burn is usually somewhat more intense thansecond-degree burn. the pain of a first-degree burn.bullous pemphiguoid A disease characterized burn, third degree A burn in which the damageby tense, blistering eruptions of the skin caused by has progressed to the point of skin death. The skininflammation associated with antibodies in the base- is white and without sensation. In extreme casesment membrane layer of skin. It is diagnosed by damage may extend beyond the skin and into under-skin biopsy showing the abnormal antibodies lying tissue. In these cases the skin may be black-deposited in the skin layer. Treatment is with topical ened or burned away. Unless skin grafts are feasible,cortisone creams but sometimes requires high loss of the affected limb, permanent disfigurement,doses of cortisone (steroids) or other medicines and even death are likely in such severe cases.taken internally. burning mouth syndrome An intense burningbump A raised area resulting from blood and sensation on the tongue, often at the tip of theserum leaking from injured blood vessels into the tongue. Burning mouth syndrome tends to developtissues, as well as from the body’s inflammatory in “supertasters”—people with an unusually largeresponse to the injury. A purplish, flat bruise that density of taste buds, each surrounded by painoccurs when blood leaks out into the top layers of fibers—and in postmenopausal women, who mayskin is referred to as an ecchymosis. lose their ability to sense bitter tastes as a result of burning mouth syndrome.BUN Blood urea nitrogen. burp 1 Gas brought up from the stomach throughbunion A localized, painful swelling at the base of the mouth, producing a guttural noise. 2 As athe big toe due to new bone formation. The affected verb, to bring up gas from the stomach through thetoe is often curved outward. Bunions are frequently mouth. Also, to help a baby bring up gas after feed-associated with inflammation of the nearby bursa ing, by rubbing or patting its back. Also known as(bursitis) and degenerative joint disease eructation.(osteoarthritis). Bunions most commonly affectwomen, particularly those who wear tight-fitting bursa A closed, fluid-filled sac that functions as ashoes and high heels. Treatment includes rest, a gliding surface to reduce friction between tissues ofchange in shoes, foot supports, medications, or sur- the body. When a bursa becomes inflamed, the con-gery. dition is known as bursitis.Burkitt lymphoma A type of non-Hodgkin lym- bursitis Inflammation of a bursa, causing painphoma that most often occurs in young people and tenderness. See also bursa; bursitis, aseptic;between the ages of 12 and 30. Burkitt lymphoma bursitis, calcific; bursitis, elbow; bursitis, hip;usually causes a rapidly growing tumor in the bursitis, knee; bursitis, septic; bursitis, shoulder.abdomen and, less often, tumors in the testis,sinuses, bone, lymph nodes, skin, bone marrow, or bursitis, aseptic Bursitis that is not due to ancentral nervous system. Burkitt lymphoma is a infectious condition. Treatment of noninfectioustumor of B cell origin. See also lymphoma, non- bursitis includes rest, ice, and medications forHodgkin’s. inflammation and pain. Sometimes local cortisone injections are given to quiet inflammation.burn Damage to the skin or other body partscaused by extreme heat, flame, contact with heated bursitis, calcific Chronic bursitis with calcifica-objects, or chemicals. Burn depth is generally cate- tion of the bursa. The calcium deposition can occurgorized as first, second, or third degree. The treat- as long as the inflammation is present.ment of burns depends on the depth, area, andlocation of the burn, as well as additional factors, bursitis, elbow Inflammation of the bursa at thesuch as material that may be burned onto or into the tip of the elbow, called the olecranon bursa. Theskin. Treatment options range from simply applying olecranon bursa is a common site of bursitis.a cold pack to emergency treatment to skin grafts. bursitis, hip Inflammation of a bursa of the hip.burn, first degree A superficial burn with simi- There are two major bursae of the hip, which is alar characteristics to a typical sunburn. The skin is common location for bursitis.red in color, without blistering, sensation is intact,and the burn is usually somewhat painful.
bursitis, knee 62bursitis, knee Inflammation of a bursa of the bypass An operation in which a new pathway isknee. There are three major bursae of the knee, created for the transport of substances in the body.which is a common site for bursitis. bypass, cardiopulmonary A bypass of the heartbursitis, septic Inflammation of a bursa due to and lungs as, for example, in open heart surgery. Ininfection, usually with bacteria. Septic bursitis is this procedure, blood returning to the heart istreated with antibiotics, aspiration, and surgery. diverted through a heart-lung machine (a pump-Also known as infectious bursitis. oxygenator) before being returned to the arterial circulation.bursitis, shoulder Inflammation of a bursa ofthe shoulder. There are two major bursae of the bypass, coronary A form of bypass surgery thatshoulder, which is a common location for bursitis. can create new routes around narrowed and blocked arteries, permitting increased blood flow tobutterfly rash A red, flat, butterfly-shaped facial deliver oxygen and nutrients to the heart muscles.rash over the bridge of the nose. More than half of Also known as coronary artery bypass graft (CABG)patients with systemic lupus erythematosus develop surgery, it is an option for selected patients with sig-this characteristic rash. The butterfly rash of lupus nificant narrowings and blockages of the heartis typically painless and does not itch. Along with arteries. The bypass graft for a CABG can be a veininflammation in other organs, the rash can be pre- from the leg or an inner chest-wall artery. CABG sur-cipitated or worsened by exposure to sunlight. This gery is one of the most commonly performed majorphotosensitivity can be accompanied by a worsening operations. Coronary artery disease developsof inflammation throughout the body, causing a because of hardening of the arteries (atherosclero-flare-up of the disease. A somewhat similar rash can sis) that supply blood to the heart muscle.also occur in other conditions, such as rosacea. Diagnostic tests include electrocardiogramsAlso known as a malar rash. See also lupus; lupus, (EKGs), stress tests, echocardiograms, and coro-discoid; lupus erythematosis, systemic. nary angiographies.
Army Medical Corps and a well-known symbol of Cc physicians and medicine. The Corps should have chosen the symbol of medicine: the rod of Aesculapius, which has only one snake and no wings. No wings were necessary because the essence of medicine was not speed. The single ser- pent that could shed its skin and emerge in full vigor represented the renewal of youth and health. caesarean section A procedure in which an infant is surgically removed from the uterus rather than being born vaginally. Caesarean sections wereC 1 In genetics, cytosine, a member of the G-C performed in ancient civilizations to salvage babies(guanine-cytosine) base pair in DNA. 2 In bio- upon the death of nearly full-term pregnant women.science, carbon, an essential element in the basic Julius Caesar is said to have been born by this pro-structure of living things. cedure, hence the name. The term section in sur- gery refers to the division of tissue. In the case of aC1 through C7 The seven cervical vertebrae of caesarean section, the abdominal wall of the motherthe neck. C1 supports the head and is named atlas, and the wall of the uterus are divided in order tofor the Greek god who supported the world. C2 is extract the baby. Also known as C-section.called the axis because the atlas rotates about theodontoid process, a bony projection of the axis. C7 caesarean section, lower segment A cae-is sometimes called the prominent vertebra because sarean section in which the surgical incision isof its long spine that projects from the back of the made in the lower segment of the uterus.vertebral body at the base of the neck. Abbreviated LSCS.CA 19–9 A tumor marker found in patients with caesarean section, vaginal birth after A vagi-colorectal, pancreatic, stomach, and bile duct can- nal delivery for a woman who previously had a cae-cer. sarean section. It was once the rule that after a caesarean section, the next delivery also had to beCA 125 Cancer antigen 125, a protein normally by caesarean section. Now vaginal delivery after cae-made by certain cells in the body, including those of sarean section is sometimes feasible. Age is one ofthe ovaries, Fallopian tubes, uterus, cervix, and lin- the factors that need to be considered becauseing of the chest and abdominal cavities (the pleura women over 30 who try a vaginal delivery after aand peritoneum). When CA 125 is found in higher caesarean section are more likely than youngerthan normal amounts (more than 35 kU/ml), it is women to have a uterine rupture. Abbreviatedconsidered a marker for cancer. Benign conditions VBAC.that can raise CA 125 include infections of the liningof the abdomen and chest, menstruation, preg- café au lait spot A flat spot on the skin that hasnancy, endometriosis, and liver disease. Benign a color similar to that of coffee with milk (café autumors of the ovaries can also cause abnormal test lait) in persons with light skin or that has a darkerresults. appearance than the surrounding skin in persons with dark skin. About 10 percent of the generalCABG Coronary artery bypass graft. See bypass, population has café au lait spots, which can becoronary. removed with a Yag laser technique. Café au lait spots are normally harmless, but in some cases theycachetic Having cachexia. Patients with cancer, are a sign of neurofibromatosis. The presence of sixAIDS, and other serious chronic diseases may or more café au lait spots, each of which is 1.5 cmappear cachetic. See also cachexia. or more in diameter, is diagnostic of neurofibro- matosis. See also neurofibromatosis; Yag lasercachexia General physical wasting with loss of surgery.weight and muscle mass due to a disease. Alsoknown as marasmus. caffeine A stimulant compound found naturally in coffee, tea, cocoa (chocolate), and kola nutsCAD Coronary artery disease. (cola) and added to soft drinks, foods, and medi- cines. Caffeine can cause anxiety, insomnia, nerv-caduceus A staff with two snakes entwined about ousness, and hypertension. Caffeine is a diureticit, topped by a pair of wings. The caduceus was car- and increases urination. It can decrease a person’sried by the Greek messenger god Hermes, whose ability to lose weight because it stimulates insulinRoman counterpart was Mercury, and is therefore secretion, which reduces blood sugar, whichthe sign of a herald. By a curious misconception, increases hunger. Caffeine can help to relievethe caduceus also became the insignia of the US headaches, so a number of over-the-counter and
Caffey disease 64prescription pain relievers include it as an ingredi- a microscope (granuloma) and contains calciument, usually with aspirin or another analgesic. deposits. Because it usually takes some time for cal- cium to be deposited in a granuloma, it is generallyCaffey disease An inflammatory bone disorder assumed that a calcified granuloma is an old granu-seen only in newborn and very young babies, char- loma, or an old area of inflammation. For example,acterized by swelling of soft tissues, irritability, fever, a calcified granuloma in the lung may be due toand paleness. Also known as infantile cortical tuberculosis contracted years earlier that is nowhyperostosis. inactive and dormant.calamine An astringent made from zinc carbon- calcinosis An abnormal deposit of calcium saltsate or zinc oxide, customarily used in lotion form to in body tissues. Examples include the calcificationstreat skin problems or insect bites that cause itching in the skin from scleroderma and in the muscleor discomfort. from polymyositis.calcaneal spur A bony spur, also known as a calcitonin A hormone produced by the thyroidheel spur, that projects from the back or underside gland that lowers the levels of calcium and phos-of the heel bone (the calcaneus) and that may make phate in the blood and promotes the formation ofwalking painful. Calcaneal spurs are associated with bone. Bone is in a constant state of remodeling. Oldinflammation of the Achilles tendon (Achilles ten- bone is removed by cells called osteoclasts, and newdinitis), and cause tenderness and pain at the back bone is added by cells called osteoblasts. Calcitoninof the heel, which is made worse by pushing off the inhibits bone removal by the osteoclasts and at theball of the foot. Spurs under the sole (the plantar same time promotes bone formation by thearea) are associated with inflammation of the plan- osteoblasts. Calcitonin is given in hypercalcemiatar fascia, which is the bowstring-like tissue that (high blood calcium) to lower the calcium level; instretches from the heel underneath the sole. These osteoporosis to increase bone density and decreasespurs can cause localized tenderness and pain that the risk of a fracture; and in Paget disease tois made worse by stepping down on the heel. decrease bone turnover and bone pain. Also knownCalcaneal spurs and plantar fasciitis can occur as thyrocalcitonin.alone, or they can be related to underlying diseasesthat cause arthritis, such as reactive arthritis and calcium A mineral found mainly in the hard partankylosing spondylitis. Treatment is designed to of bones, where it is stored. Calcium is added todecrease the inflammation and avoid reinjury. Heel bone by cells called osteoblasts and removed fromlifts reduce stress on the Achilles tendon and relieve bone by cells called osteoclasts. Calcium is essentialpainful spurs at the back of the heel. Donut-shaped for healthy bones and is also important for muscleshoe inserts take pressure off plantar spurs. contraction, heart action, and normal blood clot-Infrequently, surgery is done on chronically ting. Food sources of calcium include dairy foods;inflamed spurs. some leafy green vegetables, such as broccoli and collards; canned salmon; clams; oysters; calcium-calcaneocuboid joint The joint located in the fortified foods; and soy foods, such as tofu.foot between the calcaneus bone and the cuboid According to the National Academy of Sciences, ade-bone. It is a gliding type of joint. The ligaments that quate intake of calcium is 1 gram daily for both menserve to support and strengthen this joint are called and women. The upper limit for calcium intake isthe capsular, dorsal calcaneocuboid, bifurcated, 2.5 grams daily.long plantar, and plantar calcaneocuboid ligaments. calcium deficiency A low blood level of calciumcalcaneus The heel bone, a more or less rectan- (hypocalcemia), which can make the nervous sys-gular bone at the back of the foot. Also known as os tem highly irritable, causing spasms of the handscalcis. and feet (tetany), muscle cramps, abdominal cramps, overly active reflexes, and so on. Chroniccalcific bursitis Chronic inflammation of a calcium deficiency contributes to poor mineraliza-bursa (bursitis) that leads to calcium deposits in the tion of bones, soft bones (osteomalacia) and osteo-bursa. The calcification can occur as long as the porosis, and, in children, rickets and impairedinflammation is present. See also bursa; bursitis. growth.calcification The process of suffusing tissues calcium excess An elevated blood calcium levelwith calcium salts. (hypercalcemia), which can cause muscle weak- ness and constipation, affect the conduction of elec-calcified granuloma A node-like type of tissue trical impulses in the heart (heart block), lead toinflammation that has a specific appearance under calcium stones in the urinary tract, impair kidney
65 cancer, brainfunction through nephrocalcinosis, and interfere and typically last a week. They resemble the symp-with the absorption of iron, predisposing the person toms of viral gastroenteritis—diarrhea, fever,to iron deficiency. abdominal pain, cramping, nausea, and vomiting— but with campylobacter, fever is typical and the diar-calculus A stone, as in the urinary tract, or cal- rhea is often bloody. Antibiotics can be helpfulcium salt deposits on the teeth. In Latin, the word treatment. Most people recover completely.calculus means “a pebble.” Pebbles were once used However, some suffer long-term consequences,for counting, from which came the mathematical such as arthritis or Guillain-Barré syndrome. Bothfield of calculus. are thought to occur when a person’s immune sys- tem is activated by the Campylobacter jejuni andcalculus, renal See kidney stones. misdirected to attack the person’s own body.calf The belly or fleshy hind part of the back of Canavan disease A progressive, inherited disor-the leg below the knee. The calf is made up mainly der of the central nervous system that is caused by aof the gastrocnemius muscle. Pain in the calf is deficiency of the enzyme aspartoacylase. Signscommonly caused by muscle strain, but can be appearing in children between 3 and 6 months ofcaused by blood clots in veins of the legs. age include developmental delay, significant motor slowness, enlargement of the head (macrocephaly),caliper 1 A metal or plastic instrument used to loss of muscle tone (hypotonia), poor head control,measure the diameter of an object. The skin-fold and severe feeding problems. As the disease pro-thickness in several parts of the body can be meas- gresses, seizures, shrinkage of the nerve to the eyeured with calipers, as can fat deposits. This meas- (optic atrophy), and often blindness develop, as dourement is done in medicine, especially in the heartburn (gastrointestinal reflux) and deteriora-diagnosis and treatment of obesity, and in physical tion of the ability to swallow. Canavan disease isanthropology. Calipers are also used to measure the inherited as an autosomal recessive condition, withdiameter of the pelvis in pregnant women to ensure both parents silently carrying a single Canavan genethat it is large enough to permit birth. 2 A type of and each of their children running a 25 percent riskleg splint. of receiving both genes and having the disease. Canavan disease is more prevalent among individu-callus 1 A localized, firm thickening of the super- als of Eastern European Jewish (Ashkenazi) back-ficial layer of skin as a result of repetitive friction. A ground than in others. There is currently nocallus on the skin of the foot may have become thick effective treatment and affected children die in theand hard from rubbing against an ill-fitting shoe. first decade of life. Also known as spongy degener-Calluses of the feet may lead to other problems, ation of the central nervous system and Canavan-Vansuch as serious infections. Shoes that fit well can Bogaert-Bertrand disease.keep calluses from forming on the feet. Also knownas keratoma. 2 Hard new bone substance that cancer An abnormal growth of cells that tend toforms in an area of a bone fracture. It is part of the proliferate in an uncontrolled way and, in somenatural process of bone repair. cases, to metastasize (spread) to other areas of the body. Cancer is not one disease; rather, it is a hostcalor Heat, one of the four classic signs of inflam- of more than 100 different and distinctive diseases.mation together with dolor, rubor, and tumor (pain, A tumor can involve any tissue of the body. Mostredness, and swelling, respectively). types of cancer are named for the type of cell or organ in which they start. If a cancer metastasizes,calorie A unit of food energy. The word calorie is the new tumor bears the same name as the originalordinarily used instead of the more precise, scien- primary tumor. Skin cancer is the most commontific term kilocalorie. A kilocalorie represents the type of cancer in both men and women. The secondamount of energy required to raise the temperature most common types of cancer are prostate cancerof a liter of water 1° centigrade at sea level. in men and breast cancer in women. Lung cancer isTechnically, a kilocalorie represents 1,000 true the leading cause of death from cancer for bothcalories of energy. men and women in the US. Cancer is not conta-Campylobacter jejuni A bacterium that typically gious. Also known as malignancy, malignant tumor,infects the bowels. Now the leading cause of bacter- and malignant neoplasm. See also cancer, causes.ial food poisoning, Campylobacter jejuni is most cancer, bladder See bladder cancer.often spread by contact with raw or undercookedpoultry. A single drop of juice from a contaminated cancer, bone See bone cancer.chicken is enough to make someone sick.Symptoms tend to start 2 to 5 days after exposure cancer, brain See brain cancer.
cancer, breast 66cancer, breast See breast cancer. can prevent colorectal cancer. Colon polyps and early colon cancer can have no symptoms. Therefore, reg-cancer, breast, familial See breast cancer, ular screening is important, starting at age 50 (or ear-familial. lier, if added risk factors are present). Diagnosis can be made by barium enema or by colonoscopy, withcancer, breast, susceptibility gene See breast biopsy confirmation of cancer tissue. Surgery is thecancer susceptibility gene. most common treatment for colorectal cancer.cancer, causes Causes of cancer. In most indi- cancer, colorectal See cancer, colon.vidual cases, the exact cause of cancer is unknown.It’s likely that each case represents an interplay of cancer, esophagus See esophageal cancer.several factors, which may include increasedgenetic susceptibility; environmental insults, such as cancer, gastric A malignant tumor of the stom-chemical exposure or smoking cigarettes; lifestyle ach. Gastric cancer can develop in any part of thefactors, including diet; and damage caused by infec- stomach and can spread from the stomach to othertious disease. Although they are not causes per se, a organs. Symptoms of stomach cancer are oftennumber of factors—including gender, race, age, vague, such as loss of appetite and weight. Gastricand the health of the patient’s immune system—can cancer is diagnosed via a biopsy of stomach tissueinfluence the development of cancer. When com- during an endoscopy. Also called stomach cancer.mon causes for a type of cancer are discovered, thisinformation can be very helpful in prevention and cancer, Hodgkin’s lymphoma A type of lym-sometimes in treatment. For example, the link phoma (cancer of the lymphatic system). Alsobetween overexposure to the sun and skin cancer is known as Hodgkin’s disease. The most commonwell known, and individuals can easily reduce their symptom is painless swelling of the lymph nodes inrisk of skin cancer by avoiding sun tanning and sun- the neck, underarm, or groin. Most patients are inburns. Alcohol is associated with an increased risk their teens or 20s. It is diagnosed with a biopsy of anof cancer of the esophagus, mouth, pharynx, larynx, enlarged lymph node. Treatment usually includesliver, breast, rectum, and pancreas. radiation therapy or chemotherapy. Patients treated for Hodgkin’s disease have an increased risk ofcancer, cervical A malignant tumor of the cervix, developing other types of cancer, especiallythe lowest part of the uterus, which forms a canal leukemia, later in life. See also Hodgkin’s disease.that opens into the vagina. Regular pelvic exams andPap tests are of great importance and can detect cancer, kidney A malignant tumor of the kidney.precancerous changes in the cervix. The most com- Childhood kidney cancer is different from adult kid-mon symptom is abnormal bleeding. Cancer of the ney cancer. The most common type of childhoodcervix can be diagnosed by using a Pap test or other kidney cancer is Wilms tumor. The most commonprocedures that sample the cervix tissue. type of adult kidney cancer is renal cell cancer (alsoPrecancerous changes in the cervix may be treated known as renal adenocarcinoma). A frequent signwith cryosurgery, cauterization, or laser surgery. of kidney cancer is blood in the urine. The diagno-Women who begin having sexual intercourse before sis of kidney cancer is supported by findings of theage 18 and have many sexual partners are at medical history and examination, blood, urine, andincreased risk. Furthermore, women whose part- X-ray tests, and is confirmed with biopsy. Kidneyners begin having sexual intercourse at a young age cancer is treated with surgery, embolization, radia-and have many sexual partners, especially one who tion therapy, hormone therapy, biological therapy,had cervical cancer, are at increased risk. The or chemotherapy. See also cancer, renal cell;human papillomavirus (HPV) is a sexually transmit- Wilms tumor.ted virus that is a known cause of cervical cancer.Other risk factors include exposure before birth to cancer, laryngeal A malignant tumor of thethe drug diethylstilbestrol (DES), smoking, and voice box (larynx), which is located at the top of theimmunodeficiency. See also Pap test. windpipe (trachea). Cancer of the larynx occurs most often in people over the age of 55, especiallycancer, colon A malignant tumor arising from those who have been heavy smokers. People whothe inner wall of the large intestine (the colon). In stop smoking can greatly reduce their risk.the US, colon cancer is the third leading type of can- Hoarseness without pain can be a symptom of can-cer in males and the fourth in females. Risk factors cer of the larynx. The larynx can be examined withfor cancer of the colon and rectum (colorectal can- a viewing tube called a laryngoscope. Cancer of thecer) include colon polyps, long-standing ulcerative larynx is usually treated with radiation therapy orcolitis, and genetic family history. Most colorectal can- surgery. Chemotherapy can also be used for laryn-cers develop from polyps. Removal of colon polyps geal cancers that have spread.
67 cancer, renal cellcancer, lung A malignant tumor of the lung, the cancer, pancreatic A malignant tumor of themajor organ of respiration. Lung cancer kills more pancreas. Pancreatic cancer has been called amen and women than any other form of cancer. “silent” disease because early pancreatic cancerEight out of 10 lung cancers are due to damage usually does not cause symptoms. If the tumorcaused by tobacco smoke. Persistent cough and blocks the common bile duct, and bile cannot passbloody sputum can be symptoms of lung cancer. into the digestive system, the skin and whites of theDiagnosis of lung cancer can be based on examina- eyes may become yellow (jaundiced), and the urinetion of sputum or on tissue examination with biopsy, may become darker as a result of accumulated bileusing bronchoscopy, a needle through the chest pigment (bilirubin).wall, or surgical excision. cancer, penis A malignant tumor in which can-cancer, male breast See breast cancer, male. cer cells develop in the tissues of the penis. It is rare in the US. A physician should be consulted forcancer, melanoma A skin cancer that begins in growths or sores on the penis, any unusual dis-cells called melanocytes, which normally grow charge from the penis, or bleeding. If warranted, atogether to form benign (noncancerous) moles. A biopsy is performed. If cancer is found, more testschange in size, shape, or color of a mole can be a are done to find out whether the cancer has spreadsign of melanoma. Melanoma can be cured if it is to other parts of the body (staging). Treatmentdetected early. If it is not detected early, however, it options include surgery, radiation therapy,may spread to other areas of the body, and that can chemotherapy, and biological therapy. The chancecause death. Diagnosis is confirmed with a biopsy of of recovery and choice of treatment depend on thethe abnormal skin. Sun exposure can cause skin stage of the cancer and the patient’s general state ofdamage, which can in turn lead to melanoma. See health. Men who are not circumcised at birth mayalso melanoma. have a higher risk of getting cancer of the penis.cancer, multiple myeloma See multiple cancer, prostate A malignant tumor of themyeloma. prostate, the gland that produces some of the com- ponents of semen. Prostate cancer is the secondcancer, myeloma See multiple myeloma. leading cause of death of males in the US. It is often first detected as a hard nodule found during a rou-cancer, non-Hodgkin’s lymphoma See lym- tine rectal examination. The PSA blood test is aphoma, non-Hodgkin’s. screening test for prostate cancer. Diagnosis of prostate cancer is established when cancer cells arecancer, oral A malignant tumor of the mouth identified in prostate tissue obtained via biopsy. Inarea. A sore in the mouth that does not heal can be some patients, prostate cancer is life threatening. Ina warning sign of oral cancer. A biopsy is the only many others, prostate cancer can exist for yearsway to determine whether an abnormal area in the without causing any health problems. Treatmentoral cavity is cancerous. Oral cancer is almost options for prostate cancer include observation,always caused by tobacco (smoking and chewing) radiation therapy, surgery, hormone therapy, andor alcohol use. Surgery to remove the tumor in the chemotherapy.mouth is the usual treatment. cancer, rectal A malignant tumor arising fromcancer, ovarian A malignant tumor of the ovary, the inner wall of the end of the large intestine (rec-the egg sac in a female. Women who have a family tum). In the US, it is the third leading cause of can-history of ovarian cancer are at an increased risk of cer in males and the fourth in females. Risk factorsdeveloping ovarian cancer. Hereditary ovarian can- include heredity, colon polyps, and long-standingcer makes up a small percentage of all cases of ulcerative colitis. Most rectal cancers develop fromovarian cancer. Three hereditary patterns have been polyps in the colon. Removal of these polyps canidentified: ovarian cancer alone, ovarian and breast prevent cancer. Colon polyps and early rectal can-cancers, and ovarian and colon cancers. Ovarian cer can have no symptoms, so regular screening iscancer is difficult to detect early because there usu- important. Diagnosis can be made by barium enemaally are no symptoms and the symptoms that do or by colonoscopy, with biopsy confirmation of can-occur tend to be vague. Detection involves physical cer tissue. Surgery is the most common treatment.examination (including pelvic exam), ultrasound,X-ray tests, CA 125 test, and biopsy of the ovary. cancer, renal cell A malignant tumor that devel-Most ovarian growths in women under age 30 are ops in the lining of the kidney tubules that filter thebenign (noncancerous), fluid-filled cysts. blood and produce urine. Also known as renal cell carcinoma and renal adenocarcinoma. See also cancer, kidney.
cancer, skin 68cancer, skin A malignant tumor of the outer sur- cancer symptoms Symptoms that may be associ-face of the body. Skin cancer is the most common ated with cancer, including changes in bowel orcancer in the US. There are many types of skin can- bladder habits, a sore that does not heal, unusualcer; the three most common types are basal cell bleeding or discharge, thickening or a lump in thecarcinoma, squamous cell carcinoma, and the most breast or any other part of the body, indigestion ordeadly, melanoma. The main cause of skin cancer is difficulty swallowing, obvious change in a wart orultraviolet light from sunlight. Tanning lamps are a mole, and a nagging cough or hoarseness. Thesehazard in this regard. Unexplained changes in the symptoms are not always signs of cancer; they canappearance of the skin that last longer than 2 weeks result from less serious conditions. Some forms ofshould be evaluated by a physician. The cure rate cancer cause little or no discomfort until the diseasefor skin cancer could be 100 percent if all skin can- is far advanced, so it is important to see a physiciancers were brought to a physician’s attention before for regular checkups rather than wait for problemsthey had a chance to spread. See also basal cell car- to occur.cinoma; squamous cell carcinoma; melanoma. Candida albicans A yeast-like fungal organismcancer, stomach See cancer, gastric. found in small amounts in the normal human intes- tinal tract. Normally kept in check by the body’s owncancer, testicular A malignant tumor of the male helpful bacteria, C. albicans can increase in num-sex organ (testicle) that normally produces the hor- bers when this balance is disturbed causing can-mone testosterone. It is one of the most common didiasis of the intestinal tract or yeast infections ofcancers in young men. Most testicular cancers are other parts of the body. See also candidiasis.found by men themselves, as lumps in the testicles.The risk of testicular cancer is increased in males candidiasis Disease caused by the yeast Candidawhose testicles did not move down normally into the albicans. Candida albicans can cause vaginal yeastscrotum during childhood (undescended testicles). infections, diaper rash, skin rashes that emerge inWhen a growth in a testicle is detected, cancer is moist, warm folds of skin, and thrush (whiteconfirmed after surgical removal of the affected tes- patches inside the mouth and throat). Candidiasisticle (orchiectomy) and examination of the tissue tends to develop when the normal balance of bacte-under a microscope. Testicular cancer is almost ria is upset, as sometimes occurs with the use ofalways curable if it is found early. antibiotics. Prevention measures include the use of probiotics, and in some cases, dietary changes.cancer, thyroid A malignant tumor of the gland Candidiasis can be treated with antifungal medica-in front of the neck that normally produces thyroid tions. Candidiasis is usually a minor and easilyhormone, which is important to the normal regula- addressed problem, but it can be an importanttion of the metabolism in the body. There are four problem for those with immune-system disorders,major types of cancer of the thyroid gland: papillary, such as AIDS.follicular, medullary, and anaplastic. Persons whoreceived radiation to the head or neck in childhood canker sore A common small, frequently painfulshould be examined by a physician for thyroid can- and sensitive crater in the lining of the mouth. Alsocer every 1 to 2 years. The most common symptom known as aphthous ulcer. Sores typically last for 10of thyroid cancer is a lump, or nodule, that can be to 14 days and generally heal without scarring.felt in the neck. The only certain way to tell whethera thyroid lump is cancer is by examining thyroid tis- cannabis Marijuana (Cannibis sativa), a drugsue obtained via biopsy. derived from the family of plants that includes hemp. Cannabis can be smoked or eaten. Use ofcancer, uterine A malignant tumor of the uterus cannabis produces a mild sense of euphoria, as well(womb), which occurs most often in women as impairments in judgment and lengthenedbetween the ages of 55 and 70. Abnormal bleeding response time. Although cannabis use is illegal inafter menopause is the most common symptom. most parts of the world, the plant appears to haveCancer of the uterus is diagnosed based on the some potential for medical use, particularly as aresults of a pelvic examination, Pap test, biopsy of palliative for glaucoma and disease-related loss ofthe uterus, and/or dilation and curettage (D & C). appetite and wasting, as is often seen in cancer, AIDS, and other illnesses. In some areas of the US,cancer antigen 125 See CA 125. individuals whose physicians recommend the med- ical use of cannabis can obtain special permission.cancer survivor Someone who has received thediagnosis of a potentially fatal form of cancer and is cannula A hollow tube with a sharp, retractablethereby forced to face his or her own mortality. inner core that can be inserted into a vein, an artery, or another body cavity.
69 carcinoma, squamous cellcapillary A tiny blood vessel that connects an carbuncle A skin abscess (boil) that extends intoarteriole (the smallest division of an artery) with a subcutaneous layers of skin, usually caused by localvenule (the smallest division of a vein). Although infection with the bacteria Staphylococcus aureus.tiny, the capillary plays an imortant role in the cir- Treatment includes antibiotics (typically in the formculatory system. The walls of capillaries act as semi- of topical creams) and, in severe cases, surgicalpermeable membranes that permit the exchange of drainage. See also abscess.various substances, including fluids and the gasesoxygen and carbon dioxide, between the blood carcinoembryonic antigen A protein found instream and the tissues of the body. many types of cells that is associated with a devel- oping fetus and tumors and measurable by bloodcapillary hemangioma See hemangioma, cap- testing. Abbreviated CEA. Conditions that increaseillary. CEA include smoking, infection, inflammatory bowel disease, pancreatitis, cirrhosis of the liver,capitation In US health services, a fixed “per and some benign tumors (in the same organs thatcapita” amount that is paid to a hospital, clinic, or have cancers with increased CEA). The normal levelphysician for each person served. If that person is less than 2.5 ng/ml (nanograms per milliliter) inuses few services, the excess amount paid is poten- an adult nonsmoker and less than 5.0 ng/ml in atial profit for the payee. If the person uses many smoker. Benign disease rarely elevates the CEA overservices, the payee may lose money. 10 ng/ml. The main use of CEA test is as a tumor marker, especially with intestinal cancer. The mostcaps Abbreviation for capsules. common cancers that elevate CEA are in the colon and rectum. Others include cancer of the pancreas,carbohydrate One of the three nutrient com- stomach, breast, and lung, as well as certain types ofpounds, along with fat and protein, used as energy thyroid and ovarian cancer. Levels over 20 ng/mlsources (calories) by the body. Carbohydrates take before therapy are associated with cancer that hasthe form of simple sugars or of more complex already metastasized (spread). CEA tests are usefulforms, such as starches and fiber. Complex carbo- in monitoring the treatment of CEA-rich tumors.hydrates come naturally from plants. Intake of com-plex carbohydrates, when they are substituted for carcinogen A substance or an agent that causessaturated fat, can lower blood cholesterol. cancer. The International Agency for Research onCarbohydrates produce 4 calories of energy per Cancer has classified many substances andgram. When eaten, all carbohydrates are broken processes as probably or definitely causing cancerdown into the sugar glucose. in humans. The agency has divided these substances and processes into three categories: agents (such ascarbon monoxide poisoning A potentially arsenic, asbestos, and benzene); mixtures (such asdeadly condition caused by breathing carbon in coal tars, tobacco products, and smoke); andmonoxide gas, which prevents oxygenation of the exposures (such as in aluminum production, shoeblood. Common causes of carbon monoxide poison- manufacturing and repair, and the rubber industry).ing include malfunctioning furnaces and the use of One of the best-known carcinogens is ultravioletkerosene heaters or similar devices in unventilated radiation from sunlight causing skin cancers.indoor spaces. Carbon monoxide is also emitted byautomobile and other engines, so these should not carcinogenic Having a cancer-causing potential.be run in unventilated spaces, such as closedgarages. Inexpensive alarms are available that can carcinoma Cancer that begins in the skin or indetect dangerous buildups of carbon monoxide. The tissues that line or cover body organs. Examples aretreatment for carbon monoxide poisoning is imme- carcinoma of the breast, colon, liver, lung, pan-diate reoxygenation of the blood in a hospital. creas, prostate, or stomach.carboxyhemoglobin Hemoglobin that has car- carcinoma, large cell See large cell carci-bon monoxide instead of the normal oxygen bound noma.to it. Carbon monoxide has a much stronger bind-ing to hemoglobin than oxygen. Carboxyhemoglobin carcinoma, squamous cell Cancer that beginsis formed in carbon monoxide poisoning and leads in squamous cells, which are thin, flat cells thatto oxygen deficiency in the body. The source of the resemble fish scales. Squamous cells are found incarbon monoxide may be exhaust (such as from a the tissue that forms the surface of the skin and thecar, truck, boat, or generator), smoke from a fire, lining of some organs of the body. See also carci-or tobacco smoke. The level of carboxyhemoglobin noma in situ, squamous cell.is a measure of the degree of carbon monoxideexposure.
carcinoma, transitional cell 70carcinoma, transitional cell Cancer that devel- cardiac conduction system The electrical con-ops in the lining of the renal pelvis, ureter, or blad- duction system that stimulates the heart to contractder. and pump blood. This system generates electrical impulses and conducts them throughout the musclecarcinoma in situ Cancer that has stayed in the of the heart. Among the major elements in the car-place where it began and has not spread to neigh- diac conduction system are the sinoatrial node, theboring tissues (for example, squamous cell carci- atrioventricular (AV) node, and the autonomic nerv-noma in situ). ous system. See also atrioventricular node; auto- nomic nervous system; sinoatrial node.carcinoma in situ, squamous cell An earlystage of skin cancer that develops from squamous cardiac defibrillator, implantable A devicecells (the flat, scale-like cells in the outer layer of that is designed to be put in the body to recognizethe skin). The hallmark is a persistent, progressive, certain types of abnormal heart rhythms (arrhyth-slightly raised, red, scaly, or crusted plaque that may mias) and correct them by delivering precisely cal-occur anywhere on the skin surface or on mucosal ibrated and timed electrical shocks to restore asurfaces, such as in the mouth. Under a micro- normal heartbeat. Defibrillators continuously mon-scope, atypical squamous cells are seen to have pro- itor the heart rhythm in order to detect overly rapidliferated through the whole thickness of the life-threatening arrhythmias, such as ventricularepidermis (the outer layer of the skin) but not tachycardia (rapid regular beating of the ventricles,beyond. Squamous cell carcinoma in situ is com- the bottom chambers of the heart) or ventricularmonly caused by sun exposure, but can be from fibrillation (rapid irregular beating of the ventri-prolonged exposure to arsenic. Also known as cles). Today’s implantable defibrillators can beBowen disease. implanted with less invasive surgical techniques than in the past.carcinoma of the breast, infiltrating ductalOne of several recognized specific patterns of can- cardiac index A cardiodynamic measure basedcer of the breast, so named because it begins in the on the cardiac output, which is the amount of bloodcells that form the ducts of the breast. It is the most the left ventricle ejects into the systemic circulationcommon form of breast cancer. On a mammogram, in one minute, measured in liters per minuteinvasive ductal carcinoma is usually visualized as a (l/min). Cardiac output is indexed to a patient’smass with fine spikes radiating from the edges body size by dividing by the body surface area to(spiculation). It can sometimes be felt as a firm yield the cardiac index.lump in the breast. Treatment may include radia-tion, chemotherapy, and surgery. cardiac muscle A type of muscle tissue that is found only in the heart and is distinguishable fromcarcinoma of the breast, infiltrating lobular the two other forms of muscle, smooth muscle (thatThe second most common type of invasive breast moves internal organs, such as the bowels, and ves-cancer. Infiltrating lobular carcinoma starts in the sels, such as the artery walls) and skeletal muscleglands that secrete milk (lobules). On a mammo- (that powers joints). Cardiac muscle is responsiblegram, a lobular carcinoma can look similar to a for pumping blood throughout the body.ductal carcinoma, appearing as a mass with finespikes radiating from the edges (spiculation). cardiac output The amount of blood the heartInfiltrating lobular carcinoma can cause a thicken- pumps through the circulatory system in a minute.ing of the breast tissue. Lobular carcinoma can The amount of blood put out by the left ventricle ofoccur in more than one site in the breast or in both the heart in one contraction is called the stroke vol-breasts at the same time. Treatment may include ume. The stroke volume and the heart rate deter-radiation, chemotherapy, and surgery. mine the cardiac output. A normal adult has a cardiac output of 4.7 liters (5 quarts) of blood percardiac Having to do with the heart. minute.cardiac aneurysm See aneurysm, cardiac. cardiac septum The dividing wall between the right and left sides of the heart. That portion of thecardiac arrest A heart attack in which the heart septum that separates the two upper chambers (thesuddenly stops pumping sufficient blood. A cardiac right and left atria) of the heart is termed the atrialarrest that results in the death of heart muscle is (or interatrial) septum; the portion that liesreferred to as a myocardial infarction. See also between the two lower chambers (the right and leftmyocardial infarction, acute. ventricles) of the heart is called the ventricular (or interventricular) septum.cardiac atrium See atrium.
71 carotid arterycardiac tamponade See tamponade, cardiac. of the peripheral vascular system, and congenital heart disease.cardiac ventricle See ventricle, heart. cardiovascular system The heart and bloodcardiologist A physician who specializes in treat- vessels. Also known as circulatory system.ing heart disorders. cardioversion The conversion of a cardiac rhythmcardiology The study and treatment of heart dis- or electrical pattern to another, generally from anorders. abnormal one to a normal one. Cardioversion can be accomplished by using medications or by electricalcardiomyopathy Disease of the heart muscle shock with a special defibrillator.(myocardium). cardioverter A defibrillator that is used in car-cardiomyopathy, hypertrophic A heart defect dioversion (the conversion of one cardiac rhythm tocharacterized by increased thickness (hypertrophy) another). See also cardiac defibrillator,of the wall of the left ventricle, the largest of the four implantable.chambers of the heart. carditis Inflammation of the heart.cardioplegia Paralysis of the heart, as may bedone electively in stopping the heart during cardiac care, ambulatory See ambulatory care.surgery. Cardioplegia may be done using chemicals,cold (cryocardioplegia), or electrical stimulation. care, managed See managed care.cardiopulmonary Having to do with both the care, nail See nail care.heart and lungs. care proxy, health See health care proxy.cardiopulmonary bypass Bypass of the heartand lungs (for example, during open-heart sur- caries Dental cavities in the two outer layers of agery). Blood returning to the heart is diverted tooth (the enamel and the dentin). Small caries maythrough a heart-lung machine (a pump-oxygenator) not cause pain, and may not be noticed by thebefore it is returned to the arterial circulation. The patient. Larger caries can collect food, and the innermachine does the work of both the heart and the pulp of the affected tooth can become irritated bylungs, by pumping blood as well as supplying oxy- bacterial toxins or by foods that are cold, hot, sour,gen to red blood cells. or sweet causing a toothache. Caries are caused by the Streptococcus bacteria, which produces ancardiopulmonary resuscitation A life-saving enamel-dissolving acid as it devours carbohydrateemergency procedure that involves breathing for the deposits (plaque) on the teeth. To prevent caries,victim and applying external chest compression to one should brush and floss the teeth daily, use amake the heart pump. Abbreviated CPR. In the early bacteriocidal mouthwash, and have regular dentalstages of a heart attack, death can often be avoided cleanings by a professional. If caries do occur, theif a bystander starts CPR within 5 minutes of the eroded area can be cleaned and filled by a dentist toonset of ventricular fibrillation. When paramedics prevent further damage.arrive, medications and/or electrical shock (car-dioversion) to the heart can be administered to con- carotene, beta See beta carotene.vert ventricular fibrillation to a normal heartrhythm. Prompt CPR and rapid paramedic response carotenemia An excessive blood level ofcan improve the chances of survival from a heart carotene, which causes a temporary yellowing of theattack. skin (pseudojaundice). Carotenemia is most com- monly seen in infants fed too much mashed carrotscardiovascular Relating to the circulatory sys- and adults consuming high quantities of carrots,tem, which comprises the heart and blood vessels carrot juice, or beta carotene in supplement form.and carries nutrients and oxygen to the tissues ofthe body and removes carbon dioxide and other carotid Pertaining to the carotid artery and thewastes from them. Cardiovascular diseases are con- area near that key artery, which is located in theditions that affect the heart and blood vessels and front of the neck.include arteriosclerosis, coronary artery disease,heart valve disease, arrhythmia, heart failure, hyper- carotid artery Either of the two key arteriestension, orthostatic hypotension, shock, endocardi- located in the front of the neck, through whichtis, diseases of the aorta and its branches, disorders blood from the heart goes to the brain. The right
carotid endarterectomy 72and left common carotid arteries are located on carrier test A test designed to detect carriers ofeach side of the neck. Together, these arteries pro- a gene for a recessive genetic disorder. For exam-vide the principal blood supply to the head and ple, carrier testing is done for the sickle cell trait,neck. The left common carotid artery arises directly thalassemia trait, and Tay-Sachs gene.from the aorta. The right common carotid arteryarises from the brachiocephalic artery, which, in cartilage Firm, rubbery tissue that cushionsturn, comes off the aorta. Each of the two divides to bones at joints. A flexible kind of cartilage makes upform external and internal carotid arteries. other parts of the body, such as the larynx and theCholesterol plaque on the inner wall of the carotid outside parts of the ears.artery can lead to a stroke. casein The main protein found in milk and othercarotid endarterectomy An operation to clear dairy products.the carotid artery of buildup of cholesterol-contain-ing matter along its inner wall. See also endarterec- cast 1 A protective shell of plaster and bandagetomy. that is molded to protect a broken or fractured limb as it heals. 2 An abnormal mass of dead cells thatcarpal tunnel A tunnel in the wrist formed by forms in a body cavity. For example, casts of cellsbone and tissues in the palm side of the wrist that that form in the tubules of the kidneys are some-provides passage for the median nerve to the hand. times detected in urine samples.carpal tunnel release A surgical procedure to casting The application of a molded orthopedicrelieve pressure exerted on the median nerve within appliance, usually composed of plaster or fiber-the carpal tunnel causing carpal tunnel syndrome. glass, to immobilize part or all of a limb for the pur-Surgical release is performed via a small incision, pose of healing injured tissues.using conventional surgery techniques or a fiber-optic scope (endoscopic carpal tunnel repair). casting, serial The use of successive casts to reshape deformed or spastic limbs or contractedcarpal tunnel syndrome Compression and irri- joints.tation of the median nerve as it passes under thetransverse carpal ligament in the wrist. Abbreviated castration Removal or destruction of the sexCTS. CTS can be due to trauma from repetitive work, glands. The term is usually used in reference to thesuch as that of retail checkers and cashiers, assem- testicles, but it also can apply to the ovaries.bly line workers, meat packers, typists, writers, andaccountants. Other factors that can cause CTS CAT scan Computerized axial tomography scan.include obesity, pregnancy, hypothyroidism, arthri- CAT scanning is a painless X-ray test in which a com-tis, and diabetes. The symptoms of CTS include puter generates cross-section views of a patient’snumbness, tingling, a “pins and needles” feeling anatomy. It can identify normal and abnormal struc-especially at night in the hand, particularly in the tures, and it can be used to guide procedures.thumb, index, and middle fingers. CTS can also Iodine-containing contrast material is sometimescause wrist pain, weakness in the grip, and a feeling used in CAT scanning. A patient who is allergic toof hand incoordination. In some cases the pain iodine or contrast materials and is scheduled to haveseems to migrate up from the wrist and into the a CAT scan should notify the physician and the radi-arm, shoulder, and neck. The diagnosis is suspected ology staff about the allergy. Also known as CT scan.based on symptoms, supported by signs on physicalexamination, and confirmed by nerve conduction cat scratch disease See cat scratch fever.testing. Treatment depends on the severity of symp- cat scratch fever An infection caused by thetoms and the underlying cause. Early CTS is usually Bartonella henslae bacteria. Almost half of alltreated by modification of activities, a removable domestic cats carry these bacteria and can transmitwrist brace, exercises and/or manipulation (mas- it to humans through a scratch or bite. Cat scratchsage), and anti-inflammatory medicines. If detected fever causes swelling of the lymph nodes, soreearly, CTS is reversible. If numbness and pain con- throat, fatigue, fever, chills, sweats, vomiting, loss oftinue in the wrist and hand, cortisone injection into appetite, and weight loss. There is usually a littlethe carpal tunnel can help. Surgery is used only bump (a papule), which may be pus-filled (a pus-when other treatments have failed. In advanced CTS, tule), at the site of the scratch. In people withparticularly if there is profound weakness and mus- immunodeficiency, cat scratch fever can progress tocle atrophy (wasting), surgery is done to avoid per- bacillary angiomatosis, a bacterial skin infectionmanent nerve damage. that can be treated with the antibiotics rifampin, ciprofloxacin, trimethoprim-sulfamethoxazole, and gentamicin.
73 caudalcatabolism See metabolism. drainage. After the catheter is inserted in the blad- der, a balloon on the bladder end is inflated with aircatalepsy A body’s persistence in unusual pos- or fluid so that the catheter cannot be removed.tures, with waxy rigidity of the limbs, mutism, and Removal is accomplished by deflating the ballooncomplete inactivity, regardless of outside stimuli, as and slipping the catheter out. See also catheter,is sometimes seen in catatonic schizophrenia. indwelling bladder.catalyst A substance that speeds up a chemical catheter, indwelling bladder A catheterreaction but is not consumed or altered in the inserted into the bladder that remains there to pro-process. Catalysts are of immense importance in vide continuous urinary drainage. The principalchemistry and biology. All enzymes are catalysts that type is the Foley catheter. See also catheter, Foley.expedite the biochemical reactions necessary forlife. The enzymes in saliva, for example, accelerate catheter, IV A catheter placed in a vein to pro-the conversion of starch to glucose, doing in min- vide a pathway for drugs, nutrients, fluids, or bloodutes what would otherwise take weeks. products. Blood samples can also be withdrawn through an IV catheter.cataplexy A debilitating condition in which a per-son suddenly feels weak and collapses at times of catheter, oximetry A catheter used with moni-strong emotion such as during laughter, anger, fear, toring equipment that can measure the amount ofor surprise. In so collapsing, people with cataplexy oxygenated hemoglobin in the bloodstream. Seemay injure themselves. For example, laughter and also catheter, Swan-Ganz.other emotions may trigger a reflex that can bringmany of the muscles of the body to the point of col- catheter, PA A catheter that is inserted into thelapse. Cataplexy often affects people who have nar- pulmonary artery.colepsy. catheter, Swan-Ganz A style of oximetrycataract A clouding or loss of transparency of the catheter that is inserted into a major vein under thelens in the eye as a result of increased water con- collarbone or in the neck, threaded through thetent. There are many causes of cataracts, including right side of the heart, and then threaded into theaging, cortisone medication, trauma, diabetes, and pulmonary artery. Physicians can use monitoringother diseases. Cataracts affect most people who live equipment with a Swan-Ganz catheter to measureinto old age. Symptoms include double or blurred blood pressure inside the heart and to find out howvision and sensitivity to light and glare. A physician much blood the heart is pumping.can diagnose cataracts by examining the eyes with aviewing instrument. Sunglasses can help to prevent cathexis In psychiatry, the concentration of psy-cataracts. See also cataract surgery. chic energy on an idea.cataract surgery Removal of the clouded cauda equina A bundle of spinal nerve roots that(cataractous) lens in its entirety via surgery and arise from the end of the spinal cord. The caudareplacement of the lens with an intraocular lens equina comprises the roots of all the spinal nerves(IOL) made of plastic. A typical cataract operation below the first lumbar (L1) vertebra in the lowertakes about an hour, requires local anesthesia only, back.and usually does not require hospitalization. cauda equina syndrome Impairment of thecatatonic In a state of catalepsy. See catalepsy. nerves in the cauda equina, characterized by dull pain in the lower back and upper buttocks and lackcath Medical shorthand for catheter or a proce- of feeling (analgesia) in the buttocks, genitalia, anddure using a catheter. thigh, together with disturbances of bowel and blad- der function.cathartic A laxative. caudad Toward or of the feet or tail. The oppositecatheter A thin, flexible tube. of cranial. See also Appendix B, “Anatomic Orientation Terms.”catheter, bladder A flexible plastic tube insertedinto the bladder. See also catheter, Foley; catheter, caudal 1 An anatomic term pertaining to, situ-indwelling bladder. ated in, or directed toward the tail or the hind part. 2 Inferior to another structure, in the sense of beingcatheter, Foley A flexible plastic tube inserted below it.into the bladder to provide continuous urinary
caudal anesthesia 74caudal anesthesia Anesthesia produced by because of its location and its contents, whichinjection of a local anesthetic into the caudal canal, include the third cranial (oculomotor) nerve, thethe sacral portion of the spinal canal. Caudal anes- fourth cranial (trochlear) nerve, parts 1 (the oph-thesia is used to provide anesthesia and analgesia thalmic nerve) and 2 (the maxillary nerve) of the(pain relief) below the umbilicus. It may be the sole fifth cranial (trigeminal) nerve, and the sixth cranialanesthetic or combined with general anesthesia. (abducens) nerve.Also known as caudal epidural anesthesia or a cau-dal block. cavernous sinus syndrome A condition char- acterized by swelling of the eyelids and the conjunc-caudal regression syndrome A disorder char- tivae of the eyes, as well as paralysis of the cranialacterized by absence of all or part of the sacrum and nerves that course through the cavernous sinus. It isdysfunction of the bowels, bladder, and legs. About caused by a cavernous sinus thrombosis.20 percent of children with caudal regression areborn to mothers with diabetes. Treatment involves cavernous sinus thrombosis A blood clotsurgery to correct these defects, when possible. within the cavernous sinus. A thrombosis in this key crossroads causes cavernous sinus syndrome.caul Folk term for the membranes that surroundthe fetus in the womb, particularly for the presence cavity See caries.of these membranes over the newborn infant’s faceor head at birth, a relatively common and usually cavity, abdominal See abdominal cavity.harmless occurrence. In some cultures, the pres-ence of a caul at birth is considered spiritually sig- CBC Complete blood count, a set of values of thenificant. cellular (formed) elements of blood. CBC measure- ments are usually determined by specially designedcauliflower ear An acquired deformity of the machines that analyze the different components ofexternal ear to which wrestlers and boxers are par- blood in less than a minute. The values generallyticularly vulnerable, due to trauma. When a blood included in a CBC are the following:clot (hematoma) forms under the skin of the ear, • The number of white blood cells in a vol-the clot disrupts the connection of the skin to the ume of blood. The normal range variesear cartilage. The cartilage has no other blood sup- slightly among laboratories but is gener-ply except from the overlying skin, so if the skin is ally between 4,300 and 10,800 cells perseparated from the cartilage, it is deprived of nutri- cubic millimeter (cmm).ents and dies. The ear cartilage then shrivels up toform the classic cauliflower ear, so named because • The automated white cell differential,the tissue resembles that lumpy vegetable’s surface. which is a machine-generated percentageTreatment involves draining the blood clot through of the different types of white blood cells,an incision in the ear and then applying a compres- usually split into granulocytes, lympho-sive dressing, to sandwich the two sides of the skin cytes, monocytes, eosinophils, andagainst the cartilage. basophils. • Red cell count, which is the number ofcausalgia Intense burning pain and sensitivity to red blood cells in a volume of blood. Thethe slightest vibration or touch, usually in the hand normal range varies slightly among labo-or foot, at a site some distance removed from a ratories but is generally between 4.2 andwound that has healed. 5.9 million cells/cmm. • The amount of hemoglobin in a volumecauses of cancer See cancer, causes. of blood. The normal range for hemoglo-cauterization The use of heat to destroy abnor- bin is different between the sexes; it ismal cells. Also known as diathermy and electro- approximately 13–18 g/deciliter for mendiathermy. and 12–16 g/deciliter for women (inter- national units 8.1–11.2 millimoles/litercavernous hemangioma See hemangioma, for men and 7.4–9.9 millimoles/liter forcavernous. women). • Hematocrit, the ratio of the volume of redcavernous sinus A large channel of venous cells to the volume of whole blood. Theblood that creates a cavity (sinus) bordered by the normal range for hematocrit is differentsphenoid bone and the temporal bone of the skull. between the sexes and is approximatelyThe cavernous sinus is an important structure 45 to 52 percent for men and 37 to 48 percent for women.
75 cell cloning • Mean cell volume, which is the average cDNA Complementary DNA. volume of a red cell. This is a calculated value derived from the hematocrit and CEA Carcinoembryonic antigen. red cell count, and the normal range is 86–98 femtoliters. CEA assay CEA test. • Mean cell hemoglobin, which is the aver- cecal Pertaining to the cecum. age amount of hemoglobin in the average red cell. This is a calculated value that is cecum The first portion of the large bowel, which derived from the measurement of hemo- is situated in the lower-right quadrant of the globin and the red cell count. The nor- abdomen. The cecum receives fecal material from mal range is 27–32 picograms. the small bowel (ileum), which opens into it. The • Mean cell hemoglobin concentration, appendix is attached to the cecum. which is the average concentration of hemoglobin in a given volume of red celiac disease, adult See celiac sprue. cells. This is a calculated volume that is derived from the hemoglobin measure- celiac sprue An immune disorder whereby the ment and the hematocrit. The normal small intestine is injured when exposed to gluten, a range is 32 to 36 percent. protein found in wheat and related grains. Celiac sprue causes impaired absorption and digestion of • Red cell distribution width, which is a nutrients through the small intestine. Symptoms measurement of the variability of red cell include frequent diarrhea and weight loss. A skin size. Higher numbers indicate greater condition called dermatitis herpetiformis is some- variation in size. The normal range is times associated. The most accurate test for celiac 11–15. sprue is a biopsy of the small bowel. Treatment • Platelet count, which is the number of involves avoidance of gluten in the diet. Medications platelets in a volume of blood. Platelets are used for refractory (stubborn) sprue. Also are not complete cells; they are actually known as gluten enteropathy. fragments of cytoplasm from a cell called a megakaryocyte that is found in the bone cell The basic structural and functional unit of marrow. Platelets play a vital role in any living thing. Each cell is a small container of blood clotting. The normal range varies chemicals and water wrapped in a membrane. slightly among laboratories but is in There are 100 trillion cells in a human, and each the range of 150,000–400,000/cmm contains all of the genetic information necessary to (150×109/liter to 400×109/liter). manufacture a human being. This information isCBT Cognitive behavior therapy. encoded within the cell nucleus in 6 billion subunits of DNA called base pairs. These base pairs are pack-CCP antibody See citrulline antibody. aged in 23 pairs of chromosomes, with 1 chromo- some in each pair coming from each parent. EachCD4 Transmembrane glycoprotein, which is of the 46 human chromosomes contains the DNAexpressed by T-4 cells (also known simply as T for thousands of individual genes.cells). See also T cell; T-4 cell. cell, alpha See alpha cell, pancreatic.CD4 count, absolute See T-4 count. cell, beta See beta cell, pancreatic.CD8 Transmembrane glycoprotein expressed byT-8 cells. See also T lymphocyte, cytotoxic; T-sup- cell, delta See delta cell, pancreatic.pressor cell. cell, germ The egg or sperm. Each mature germCDC The Centers for Disease Control and cell is haploid, meaning that it has a single set of 23Prevention, the US agency charged with tracking chromosomes that contains half the usual amountand investigating public health trends. A part of the of DNA and half the usual number of genes. ThisUS Public Health Services (PHS) under the makes germ cells notable exceptions to the usualDepartment of Health and Human Services (HHS), rules governing chromosomes, genes, and DNA.the CDC is based in Atlanta, Georgia. It publishes cell, reproductive See cell, germ.key health information, including weekly data on alldeaths and diseases reported in the US and travel- cell cloning The process of producing a group ofers’ health advisories. The CDC also fields special cells that are genetically identical (clones) to a sin-rapid-response teams to halt epidemic diseases. gle ancestral cell.
cell cycle 76cell cycle The sequence of events within the cell central line An infusion tube located in or nearbetween mitotic (cell) divisions. The cell cycle is the heart, which is at the center of the circulatoryconventionally divided into five phases: G0 (the system. For example, a Swan-Ganz catheter with itsgap); G1, (the first gap); S (the synthesis phase, tip in the right atrium and ventricle of the heart is aduring which the DNA is synthesized and repli- central line.cated); G2 (the second gap); and M (mitosis). Cellsthat are not destined to divide again are considered central nervous system That part of the nerv-to be in the G0 phase. The transition from G0 to G1 ous system that consists of the brain and spinalis thought to commit the cell to completing the cell cord. Abbreviated CNS. The CNS is one of the twocycle by dividing. major divisions of the nervous system. The other is the peripheral nervous system (PNS), which is out-cellulite In popular language, deposits of fat that side the brain and spinal cord. The PNS connectshave a cottage cheese-like texture. Medically, cel- the CNS to sensory organs, such as the eye and ear,lulite is not considered abnormal. and to other organs of the body, muscles, blood ves- sels, and glands.cellulitis A spreading bacterial infection under-neath the skin surface characterized by redness, central nervous system, spongy degenerationwarmth, swelling, and pain. Cellulitis commonly of the See Canavan disease.appears in areas where there is a break in the skin. central vision A process in which millions ofCenters for Disease Control and Prevention cells change light into nerve signals that tell theSee CDC. brain what the person is seeing. As a person reads, drives, and performs other activities that requireCentigrade A thermometer scale in which the fine, sharp, straight-ahead vision, light is focusedfreezing point of water at sea level is 0°C and the onto the macula in the center of the retina, the light-boiling point of water at sea level is 100°C. The sensitive layer of tissue at the back of the eye.Centigrade scale is used in most of the world to indi-cate the temperature on a thermometer, but the centromere The “waist” of the chromosome thatFahrenheit scale is still popular in the US. This is essential for the division and retention of theanachronism requires conversion from Centigrade chromosome in the cell. The centromere is a(°C) to Fahrenheit (°F), and vice versa. 1°C = uniquely specialized region of the chromosome to(5/9) (°F–32). 1°F = (9/5)(°C) + 32°. which spindle fibers attach during cell division.centimorgan A unit of measure of genetic cephal- Prefix indicating the head.recombination frequency. Abbreviated cM. One cMis equal to a 1 percent chance that a marker at one cephalgia Headache.genetic locus will be separated from a marker atanother locus due to crossing over in a single gen- cephalgia, histamine See cluster headache.eration. In humans, 1 cM is equivalent, on average,to 1 million base pairs. cephalosporin antibiotics A group of more than 20 antibiotic drugs that are based on com-central auditory processing disorder A neu- pounds originally isolated from the fungusrological disorder in which a person has difficulty Cephalosporium acremonium. See also antibiotic.properly interpreting sounds received by the ears,particularly the phonemes of speech. Abbreviated cephalothoracic lipodystrophy A disorderCAPD. CAPD can result in difficulties with attention, characterized by painless symmetrical diffusespeech production, and reading. deposits of fat beneath the skin of the neck, upper trunk, arms, and legs. The condition is genetic andcentral core disease of muscle One of the is inherited as an autosomal dominant trait. Alsoconditions that produces “floppy baby” syndrome. known as multiple symmetrical lipomatosis,Central core disease of muscle causes hypotonia Launois-Bensaude syndrome, Madelung disease,(low muscle tone) in a newborn baby, slowly pro- and familial benign cervical lipomatosis.gressive muscle weakness, and muscle cramps afterexercise. Muscle biopsy shows a key diagnostic cerclage Encirclement with a ring, loop, wire, orfinding of absent mitochondria in the center of ligature. Cerclage can be done around bone frag-many muscle fibers. It is caused by an abnormal ments to hold them together, but it usually refers togene on chromosome 19 involving ryanodine recep- an operation performed on the cervix to prevent ator 1, and is inherited as a dominant trait. miscarriage.
77 cervicalcerebellar Pertaining to the cerebellum, the part the thalamus and hypothalamus on either side. Inof the brain in the back of the head between the front, the third ventricle communicates with the lat-cerebrum and the brain stem. eral ventricles, and in back it communicates with the aqueduct of the midbrain (also known as thecerebellum The portion of the brain that is in the aqueduct of Sylvius). The fourth ventricle, which isback of the head, between the cerebrum and the the lowest of the four ventricles of the brain, extendsbrain stem. It is involved in the control of voluntary from the aqueduct of the midbrain to the centraland involuntary movement as well as balance. canal of the upper end of the spinal cord, with which it communicates, through the two foraminacerebral Of or pertaining to the cerebrum or the of Luschka and the foramen of Magendie. The ven-brain. tricles are filled with cerebrospinal fluid.cerebral aneurysm See aneurysm, brain. cerebritis Inflammation of the brain. Cerebritis can be caused by infection or inflammation fromcerebral fornix An arching fibrous band in the disease.brain that connects the two lobes of the cerebrum.There are two such bands, each of which is an cerebrospinal fluid A watery fluid that is con-arched tract of nerves. tinuously produced and absorbed and that flows in the ventricles within the brain and around the sur-cerebral hemisphere One of the two halves of face of the brain and spinal cord. Abbreviated CSF.the cerebrum, which is the largest part of the brain. CSF is produced by the choroid plexus, a series of infolded blood vessels that project into the cerebralcerebral palsy An abnormality of motor function ventricles, and it is absorbed into the venous system.(the ability to move and control movements) that is If production exceeds absorption, CSF pressureacquired at an early age, usually less than 1 year, rises, and the result is hydrocephalus. This can alsoand is due to a brain lesion that is nonprogressive. occur if the CSF pathways are obstructed, causingAbbreviated CP. CP is frequently the result of abnor- the fluid to accumulate. The CSF obtained during amalities that occur while a fetus is developing inside lumbar puncture is analyzed to detect disease.the womb. Such abnormalities may include acci-dents of brain development, genetic disorders, cerebrovascular accident See stroke.stroke due to abnormal blood vessels or bloodclots, or infection of the brain. In rare instances, cerebrovascular disease Disease of the arteriesobstetrical accidents during particularly difficult that supply blood to the brain. Cerebrovascular dis-deliveries can cause brain damage and result in CP. ease is usually caused by atherosclerosis and canCP can take three forms: spastic, choreoathetoid, lead to a stroke. See also atherosclerosis; stroke.and hypotonic (flaccid). In spastic CP, there is anabnormality of muscle tone in which one or more cerebrum The largest part of the brain, which isextremities (arms or legs) are held in a rigid pos- divided into two hemispheres (halves). The left andture. Choreoathetoid CP is associated with abnor- right hemispheres are connected by two archingmal, uncontrollable writhing movements of the bands of nerves (cerebral fornices). See also cere-arms and/or legs. A child with hypotonic CP appears bral fornix.floppy—like a rag doll. Treatment may include theuse of casting and braces to prevent further loss of ceruloplasmin deficiency A genetic disorderlimb function, speech therapy, physical therapy, that is due to a lack of ceruloplasmin, a protein thatoccupational therapy, the use of augmentative com- is involved in iron transport. The absence of cerulo-munication devices, and the use of medications or plasmin leads to the abnormal deposition of iron inbotulism toxin (botox) injections to treat spasticity. the pancreas (causing diabetes), liver (causing cir- rhosis), retina (damaging vision), and brain (caus-cerebral ventricle One of a system of four com- ing dementia and Parkinson’s disease). Aggressivemunicating cavities within the brain that are contin- treatment with deferoxamine, a chelating agent thatuous with the central canal of the spinal cord. They takes up iron, halts the progression of these com-include two lateral ventricles in the cerebral hemi- plications. Also known as aceruloplasminemia.spheres, each consisting of a triangular central bodyand four horns. The lateral ventricles communicate cervical Having to do with any kind of neck,with the third ventricle through an opening called including the neck on which the head is perchedthe interventricular foramen. The third ventricle, a and the neck of the uterus.median (midline) cavity in the brain, is bounded by
cervical cancer 78cervical cancer See cancer, cervical. chalazion See cyst, Meibomian.cervical cap A specially fitted contraceptive CHAMPUS Civilian Health and Medical Programdevice that bars the entry of sperm into the cervix. of the Uniformed Services. CHAMPUS is a US feder-The cervical cap is a thimble-shaped dome made of ally funded health program that provides benefici-latex rubber and is much smaller than a diaphragm. aries with medical care, supplemental to thatFor best results, a cervical cap is customarily used available in US military and Public Health Servicewith spermicidal gel or cream. See also birth con- facilities. All CHAMPUS beneficiaries switch to usingtrol; contraceptive. Medicare at age 65. CHAMPUS is like Medicare in that the government contracts with private parties tocervical cerclage The process of encircling a administer the program. CHAMPUS was revampedcervix that is abnormally liable to dilate (an incom- as a managed care system and renamed TRICARE.petent cervix) with a ring or loop to prevent a mis-carriage. chancre The classic nonpainful ulcer of syphilis that teems with spirochetes. A chancre forms in thecervical intraepithelial neoplasia The growth first (primary) stage of syphilis, is highly conta-of abnormal precancerous cells on the surface of gious, and can last from 1 to 5 weeks. Syphilis canthe cervix. Grades from one to three (least to most) be transmitted from any contact with a chancre. If amay be used to describe the degree of involvement. chancre is outside the vagina or on the scrotum of the male, the use of condoms may not help in pre-cervical rib See rib, cervical. venting transmission of syphilis. Likewise, if a chan- cre is in the mouth, merely kissing an infectedcervical vertebrae The upper seven vertebrae in individual can spread syphilis. See also syphilis.the spinal column, which make up the neck. Theyare designated C1 through C7, from the top down. change of life See menopause.See C1 through C7. Charcot-Marie-Tooth disease A genetic dis-cervicitis Inflammation of the uterine cervix. ease of nerves that is characterized by progressively debilitating weakness, particularly of the limbs. Thecervix The low, narrow part of the uterus, which foremost feature is marked wasting of the extremi-forms a canal that opens from the uterus into the ties, particularly in the calves, resulting in “storkvagina. The inner surface of the cervix is covered legs.” The disease usually weakens the legs before itwith mucus. During ovulation, this mucus is spe- weakens the arms. Pes cavus (deformity of the foot)cially adapted to speed sperm to the egg. The tiny is often the first sign of the disease. The disease isopening of the cervix dilates during birth to permit one of the most common genetic diseases, and it isthe newborn’s head to emerge. the most common genetic disorder of peripheral nerves. The disease can be inherited as an autoso-cervix, incompetent A cervix that has an abnor- mal dominant trait, an autosomal recessive trait, ormal tendency to dilate and so may not be able to an X-linked trait. There are also sporadic cases inkeep a fetus from being spontaneously aborted which there is no family history due to a new domi-(miscarried). nant mutation. Abbreviated CMT. Also known as peroneal muscular atrophy and hereditary motorcesarean section See caesarean section. and sensory neuropathy.CFS Chronic fatigue syndrome. charley horse Slang for a cramp in a muscle inChagas disease An infectious disease found in the leg, usually caused by a strain or injury. ACentral and South America caused by the parasite charley horse can last anywhere from a few secondsTrypanosoma cruzi. The parasite can be transmitted to over a quarter of an hour. It is not uncommon forthrough bites from bugs that carry it (known as one to recur before it finally resolves.kissing bugs) or via blood transfusion. Soon afterinfection, there may be symptoms such as swelling chart, Snellen The familiar eye chart used to measure how well a person sees at various dis-of the eye on one side of the face, usually at the bite tances. A Snellen chart is imprinted with block let-wound, but many people do not become ill until ters that decrease in size line by line, correspondingmany years after being infected. Infants and persons to the distance at which that line of letters is nor-with immunodeficiency are at risk of severe infec- mally visible.tions and complications such as meningitis andheart failure. Also known as American trypanosomi- chase the dragon A practice of heroin use thatasis. See also kissing bugs. involves heating heroin and then inhaling it. This
79 chickenpoxpractice carries a risk of irreversible brain damage men, sperm banking before treatment may be con-and death. sidered; women may choose to have eggs extracted and stored. Women’s menstrual periods may stop,cheek The side of the face, which forms the side and women may have hot flashes and vaginal dry-wall of the mouth. The cheekbone is part of the tem- ness due to induced menopause. In some cases,poral bone of the skull, and it provides the promi- bone marrow transplantation and peripheral stem-nence of the cheek. The term cheek also refers to cell support are used to replace bone marrow tissuesomething that has the form of the human cheek, that has been destroyed by the effects of chemother-particularly with two laterally paired parts, such as apy. See also adjuvant chemotherapy; cancer.a buttock. chemotherapy, adjuvant See adjuvantchemical menopause See menopause, chemi- chemotherapy.cal. cherubism A genetic disorder of childhood thatchemical reaction A process in which one sub- leads to prominence of the lower face and anstance is transformed into another. appearance reminiscent of the cherubs portrayed in Renaissance art. Cherubism is inherited as an auto-chemokine One of a large group of proteins that somal dominant condition. The gene responsibleact as chemical messengers and were first found for cherubism is called SH3BP2 (for SH3-domainattracting white blood cells to areas of inflamma- binding protein 2). Exactly how a mutation intion. Chemokines are involved in several forms of SH3BP2 leads to cherubism is not known.acute and chronic inflammation, infectious dis-eases, and cancer. chest The area of the body located between the neck and the abdomen. The chest contains thechemokine receptor A molecule that receives a lungs, the heart, and part of the aorta. The walls ofchemokine and associated proteins (chemokine the chest are supported by the dorsal vertebrae, thedocks). Several chemokine receptors are essential ribs, and the sternum. Also known as thorax.co-receptors for the HIV virus. chest film See chest X-ray.chemoprevention The use of natural or labora-tory-made substances to prevent cancer. chest pain Pain in the chest that can be a result of many things, including angina, heart attackchemotherapy Of or pertaining to treatment with (coronary occlusion), and other important dis-drugs to kill cancer cells. Most anticancer drugs are eases. Chest pain is a warning to seek medical atten-injected into a vein, but some are given by mouth. tion, so one should try not to ignore chest pain andChemotherapy is usually systemic treatment, mean- “work through it.”ing that the drugs flow through the bloodstream tonearly every part of the body. Chemotherapy is gen- chest X-ray A type of X-ray commonly used toerally given in cycles: A treatment period is followed detect abnormalities in the lungs. A chest X-ray canby a recovery period, another treatment period, and also detect some abnormalities in the heart, aorta,so on. The side effects of chemotherapy depend and the bones of the thoracic area.mainly on the drugs and doses the patient receives.Generally, anticancer drugs affect cells that divide CHF Congestive heart failure.rapidly, including blood cells, which fight infection,help the blood to clot, and carry oxygen to all parts Chiari malformation A condition in whichof the body. When white blood cells are affected by brain tissue protrudes into the spinal canal as aanticancer drugs, patients are more likely to result of a small or misshapen skull. Chiari malfor-develop infections. When red blood cells are mation is usually present at birth (congenital), butaffected, they may have decreased energy. Cells that occasionally develops after birth. Also known asline the digestive tract also divide rapidly, so Arnold Chiari malformation.chemotherapy can cause loss of appetite, nauseaand vomiting, hair loss or thinning, and mouth chickenpox A highly infectious viral diseasesores. For some patients, medicines can be pre- characterized by an itchy rash. Also known as vari-scribed to help with side effects, especially with nau- cella. It is caused by herpes zoster, a member of thesea and vomiting. Usually these side effects herpes family of viruses. Chickenpox has nothing togradually go away during the recovery period or do with chicken; the name originated to distinguishafter treatment stops. In some men and women, this mild pox from smallpox (chicken being used,chemotherapy drugs may result in temporary or as in chickenhearted, to mean weak or timid).permanent loss of the ability to have children. For Chickenpox is not a major matter unless it occurs in
chickenpox immunization 80an immunodeficient person or the pox become focation, and poisoning. Child abuse should alwaysinfected with bacteria through scratching. be reported, investigated, and stopped.Treatment, other than the use of calamine lotion orother topical solutions to diminish itching, is not child health The care and treatment of children.normally necessary. However, adults (and some- Child health is the purview of pediatrics, whichtimes children) can have major problems from became a medical specialty in the mid-nineteenthchickenpox, including pneumonia and encephalitis century. Before that time the care and treatment of(inflammation of the brain) that can lead to diffi- childhood diseases were included within such areasculty with balance and coordination (cerebellar as general medicine, obstetrics, and midwifery.ataxia). Other serious complications can includeear infections, damaged nerves (palsies), and childbed fever Fever due to an infection afterReye’s syndrome. In such cases, antiviral medica- childbirth, usually of the placental site within thetions may be tried. Reinfection with chickenpox can uterus. If the infection involves the bloodstream, itoccur. Reactivation of the chickenpox virus is constitutes puerperal sepsis. Childbed fever wasresponsible for shingles. The current aim in the US once a common cause of death for women of child-is to achieve universal immunization of children bearing age, but it is now comparatively rare in thewith the chickenpox vaccine. See also chickenpox developed world due to improved sanitary practicesimmunization; herpes zoster; neuralgia, posther- in midwifery and obstetrics. Also known as child-petic; shingles. birth fever and puerperal fever.chickenpox immunization A vaccination that childbirth See labor.prevents chickenpox. If an older person has not hadchickenpox, the shot may be given at any time. All childbirth fever See childbed fever.children, except those with compromised immunesystems or known neurological conditions, are rec- childhood 1 The time between birth until adult-ommended to have the vaccination. See also chick- hood. 2 The time from infancy to the onset ofenpox. puberty. During childhood, the potential of a unique human person must be nurtured by parents or par-chilblain An injury due to cold temperatures that, ent figures.although painful, causes little or no permanentimpairment. It appears as red, swollen skin that is childhood disintegrative disorder One of thetender and hot to the touch and may itch. This can pervasive developmental disorders (PDDs) charac-worsen to an aching, prickly (“pins and needles”) terized by apparently normal development for atsensation, and then numbness. It can develop in only least the first 2 years after birth, as manifested by thea few hours in skin exposed to extreme cold. The presence of age-appropriate verbal and nonverbaltreatment for chilblain is to stop exposure to cold, communication, social relationships, play, andremove any wet or constrictive clothing, gently wash adaptive behavior. Children with this disorder dis-and dry the injured area, elevate the injured area, play significant loss of previously acquired skillscover the injured area with layers of loose warm (before age 10 years). This loss may affect expres-clothes, and allow the injured area to rewarm. sive or receptive language, social skills or adaptive behavior, bowel or bladder control, play, or motorchild abuse A complex set of behaviors that skills. Childhood disintegrative disorder alsoinclude child neglect and the physical, emotional, involves impairment in social interaction and com-and sexual abuse of children. Although most people munication, often with the development of repetitivethink first of physical abuse when they hear the term stereotyped patterns of behavior, interests, andchild abuse, physical abuse makes up only a small activities, including motor stereotypes and manner-percentage of reported cases. Physical abuse is isms. The loss of previously acquired skills distin-defined as physical injury inflicted upon the child guishes childhood disintegrative disorder fromwith cruel and/or malicious intent, although the law autism, another PDD. See also autism; develop-recognizes that in some cases the parent or care- mental disorder.taker may not have intended to hurt the child;rather, the injury may have resulted from excessive childhood schizophrenia See schizophrenia,discipline or physical punishment. Physical abuse childhood.includes punching, beating, kicking, biting, burn- children’s immunizations Vaccinations givening, shaking, or otherwise physically harming a to children. In the US, it is currently recommendedchild. Injuries that can be fatal include severe head that all children receive vaccination against the fol-trauma, shaken baby syndrome, trauma to the lowing unless the child has special circumstances,abdomen or chest, scalding, burns, drowning, suf-
81 cholangitis, primary sclerosingsuch as a compromised immune system or a neuro- Chiropractors Association believes that patientslogical disorder: should be treated by spinal manipulation alone, whereas the American Chiropractic Association • Diphtheria, tetanus, and pertussis advocates a multidisciplinary approach that com- (whooping cough), as separate vaccina- bines spinal adjustment with other modalities, such tions or in combination as DPT as physical therapy, psychological counseling, and • Haemophilus influenzae type B (HIB) dietary measures. • Hepatitis B chlamydia The agent of a sexually transmitted • Measles, mumps, and rubella (German disease, a type of bacteria found in the cervix, ure- measles), as separate vaccinations or in thra, throat, or rectum that acts very much like gon- combination as MMR orrhea in the way it is spread, the symptoms it • Pneumococcal infections produces, and its long-term consequences. • Poliovirus Chlamydia is destructive to the Fallopian tubes, causing infertility, tubal pregnancy, and severe • Tetanus (lockjaw) pelvic infection. It is common for infected women to • Varicella zoster virus (chickenpox) have no symptoms. Chlamydia is associated with anchimera 1 An imaginary monster made up of increased incidence of preterm births. Also, anincongruous parts. 2 In medicine, a person com- infant can acquire the disease during passageposed of two genetically distinct types of cells. This through the birth canal, leading to eye problems ormay be due to the fusion of two embryos at a very pneumonia. Chlamydia is one of the reasons new-early (blastula) stage. More commonly today, the borns are routinely treated with antibiotic eyedrops.formation of a chimera is due to transplantation, Chlamydia can also cause inflammation of the ure-such as when bone marrow from one person is thra, epididymis, and rectum in men. A chronicused to reconstitute the bone marrow of an irradi- form of arthritis, called reactive arthritis, canated recipient. 3 A viral, bacterial, or other cell develop after chlamydia infection.that seems to be composed of two genetically dis- chloroform A clear, volatile liquid with a strongtinct strains, as might be seen when genetic engi- smell similar to that of ether. Chloroform was onceneering techniques are used to enclose therapeutic administered by inhalation to produce anesthesia,properties from one cell in another type of cell for given to relieve pain, and used as a remedy fordelivery. cough. It is quite toxic to the kidneys and the liver.chiropractic A system of diagnosis and treatment choana The passageway from the back of onebased on the concept that the nervous system coor- side of the nose to the throat. There are twodinates all of the body’s functions and that disease choanae, one on either side of the nose. Theresults from a lack of normal nerve function. choanae must be open to permit breathing throughChiropractic employs manipulation and adjustment the nose.of body structures, such as the spinal column, sothat pressure on nerves coming from the spinal chocolate A food or flavoring made from thecord due to displacement (subluxation) of a verte- seeds of the cacao or chocolate tree (Theobromabral body may be relieved. Practitioners believe that cacao). Chocolate is rich in flavinoids, compoundsmisalignment and nerve pressure can cause prob- that act as antioxidants. Flavinoids may also lowerlems not only in the local area, but also at some dis- blood pressure and improve blood flow by openingtance from it. Chiropractic treatment appears to be blood vessels. Thus, chocolate may have health ben-effective for muscle spasms of the back and neck, efits, provided it is consumed in moderation.tension headaches, and certain leg pain. It may ormay not be useful for other ailments. Some chiro- choked disk See papilledema.practors also recommend other forms of treatment,such as massage, diet changes, vitamins and miner- choking Partial or complete obstruction of theals, and herbal supplements. See also chiropractor. airway, usually due to the presence of food, a toy, or another foreign body in the upper throat or trachea.chiropractor A chiropractic practitioner. See also airway obstruction.Becoming a doctor of chiropractic (DC) requires aminimum of 2 years of college and 4 years in a cholangiogram A radiology procedure used toschool of chiropractic medicine. Some chiroprac- look at the gallbladder and bile ducts.tors also earn a traditional medical degree (MD) orother additional qualifications. Not all chiropractors cholangitis, primary sclerosing See primaryare alike in their practice. The International sclerosing cholangitis.
cholecystectomy 82cholecystectomy Surgical removal of the gall- exercise, and medications. After the age of 20, cho-bladder. This procedure may be done by lesterol testing is recommended every 5 years.laparoscopy or by open surgery. cholesterol, “bad” See LDL cholesterol.cholecystitis Inflammation of the gallbladder.Cholecystitis is a complication of gallstones, and it is cholesterol, “good” See HDL cholesterol.frequently associated with infection in the gallblad-der. Risk factors for cholecystitis include age, obe- cholesterol, HDL See HDL cholesterol.sity, female gender, multiple pregnancies, use ofbirth control pills, and heredity. The most common cholesterol, high-density lipoprotein Seesymptom is pain in the upper abdomen, although HDL cholesterol.some patients have no symptoms. Diagnosis can bemade with ultrasound of the abdomen. Surgery cholesterol, LDL See LDL cholesterol.(standard or laparoscopic) is considered for cholesterol, low-density lipoprotein See LDLpatients with severe cholecystitis. In some mild cholesterol.cases, medication may be used instead to treatthe infection and inflammation and to dissolve the cholesterol, lowering with fibrates Loweringgallstones. cholesterol levels through the use of cholesterol- lowering drugs that are primarily effective in lower-cholera An infectious disease characterized by ing triglycerides and, to a lesser extent, inintense vomiting and profuse watery diarrhea and increasing HDL levels. Gastrointestinal complaintsthat rapidly leads to dehydration and often death. are the most common side effect, and fibratesCholera is caused by infection with the bacteria appear to increase the likelihood of a patient’sVibrio cholerae, which may be transmitted via developing cholesterol gallstones.infected fecal matter, food, or water. With modernsanitation, cholera is no longer as common as it cholesterol, lowering with niacin Niacin, alsoonce was, but epidemics still occur whenever peo- known as nicotinic acid, is a water-soluble B vitaminple must live in crowded and unsanitary conditions, that improves levels of all lipoproteins when given insuch as in refugee camps. The disease is treated doses well above the vitamin requirement. Niacinwith intravenous fluids and with antibiotics. Cholera lowers the total cholesterol, LDL cholesterol, andhas also been known as Asian cholera, due to its triglyceride levels, while raising the HDL cholesterolone-time prevalence in that area of the world. level. A common and troublesome side effect of niacin is flushing, or hot flashes, which is a result ofcholescintigraphy A diagnostic test in which atwo-dimensional picture of a radiation source in the the widening of blood vessels. Most patients developbiliary system is obtained through the use of a tolerance for flushing, and in some patients it canradioisotopes. The test is used to examine the biliary be decreased by taking the drug during or aftersystem and diagnose obstruction of the bile ducts meals or by the use of aspirin or other similar med-(for example, by a gallstone or a tumor), disease of ications prescribed by a physician. “No-flush”the gallbladder, and bile leaks. niacin formulations are also available. A variety of gastrointestinal symptoms, including nausea, indi-cholesterol The most common type of steroid in gestion, gas, vomiting, diarrhea, and the activationthe body. Cholesterol has a reputation for being of peptic ulcers have been seen in some patientsassociated with an increased risk for heart and who use niacin. Other major adverse effects includeblood vessel disease. However, cholesterol is essen- liver problems, gout, and high blood sugar; risk oftial to the formation of bile acids, vitamin D, prog- these complications increases as the dose of niacinesterone, estrogens (estradiol, estrone, estriol), increases. The nicotinamide form of niacin does notandrogens (androsterone, testosterone), mineralo- lower cholesterol levels.corticoid hormones (aldosterone, corticosterone), cholesterol gallstone Stone within the gallblad-and glucocorticoid hormones (cortisol). der that is a result of chronically elevated blood lev-Cholesterol is also necessary to the normal perme- els of cholesterol (hypercholesterolemia). This canability and function of the membranes that surround lead to inflammation of the gallbladder (cholecysti-cells. A diet high in saturated fats tends to increase tis). See also cholecystitis.blood cholesterol levels, whereas a diet high inunsaturated fats tends to lower blood cholesterol chondrocalcinosis Calcium deposition in carti-levels. Although some cholesterol is obtained from lage. Chondrocalcinosis can be associated withthe diet, most cholesterol is made in the liver and degenerative arthritis, pseudogout, hemochromato-other tissues. The treatment of elevated cholesterol sis, hyperparathyroidism, diabetes, hypomagne-involves not only diet but also weight loss, regular semia, and Wilson’s disease.
83 chromatography, gaschondromalacia Abnormal softening or degen- uterus to infect the membranes and the amnioticeration of cartilage. See also patellofemoral syn- fluid. Chorioamnionitis is dangerous to the motherdrome. and child.chondromalacia patella See patellofemoral chorioangioma, placental A benign tumor of asyndrome. blood vessel in the placenta. Large chorioangiomas can cause complications, including excess amnioticchondroplasia The formation of cartilage by fluid (polyhydramnios), maternal and fetal clottingspecialized cells called chondrocytes. problems (coagulopathies), premature delivery, toxemia, fetal heart failure, and hydrops (excesschondrosarcoma A malignant tumor that arises fluid) affecting the fetus. Chorioangiomas probablyin cartilage cells (chondroblasts). Chondrosarcoma act as shunts between arteries and veins (arteriove-can be primary or secondary. Primary chondrosar- nous shunts), leading to progressive heart failure ofcoma forms in bone and is a disease in children. the fetus.Secondary chondrosarcoma arises from a preexist-ing benign defect of cartilage (such as an osteo- choriocarcinoma A highly malignant tumor thatchondroma or enchondroma), usually after age 40. arises from trophoblastic cells within the uterus.The main treatment is surgery. See also cartilage; Choriocarcinoma may follow any type of pregnancysarcoma. but is especially likely to occur with a hydatidiform mole. The prognosis for women with metastaticchorda tendinea A thread-like band of fibrous choriocarcinoma has improved with the advent oftissue that attaches on one end to the edge of the tri- multidrug chemotherapy. See also hydatidiformcuspid and mitral valves of the heart and on the mole.other end to the papillary muscle within the heart.The chorda tendinea serves to anchor the valves. chorion The outermost of the two fetal mem- branes (the amnion is the innermost) that surroundchorda tympani A branch of the facial nerve the embryo. The chorion develops villi (vascular(the seventh cranial nerve) that serves the taste finger-like projections) and develops into the pla-buds in the front of the tongue, runs through the centa.middle ear, and carries taste messages to the brain.The chorda tympani is part of one of three cranial chorionic gonadotropin, human See humannerves involved in taste. chorionic gonadotropin.chordoma A benign tumor, usually in the lower chorionic villus sampling A procedure forback, that originates from cells destined to form first-trimester prenatal diagnosis. Abbreviated CVS.cartilage. These cells are remnants of the primitive CVS may be done between the eighth and tenthnotochord, the flexible rod of cells in the embryo weeks of pregnancy. The aim is to diagnose severethat forms the supporting axis of the body. abnormalities that are present in the fetus. Tissue isChordomas induce bone destruction. withdrawn from the villi of the chorion, a part of the placenta, and then prepared for diagnostic analysis.chorea Ceaseless, restless, rapid, complex bodymovements that look well coordinated and pur- choroiditis An inflammation of the layer of theposeful but are, in fact, involuntary. The term eye behind the retina, either in its entirety (multifo-chorea is derived from the Greek word choreia, cal choroiditis) or in patches (focal choroiditis).which means “dancing” (as is choreography) The only symptom is usually blurred vision.because chorea was thought to be suggestive of a Choroiditis is treated with medications that reducegrotesque dance. See also Huntington’s disease; inflammation. See also uveitis.Sydenham’s chorea. Christmas disease See hemophilia B.chorea, Huntington’s See Huntington’s dis-ease. chromatid One of the two daughter strands cre- ated by the lengthwise division of the chromosome.chorea, Sydenham’s See Sydenham’s chorea. The two chromatids are at first joined together by a centromere, and then they separate, with each chro-chorioamnionitis Inflammation of the chorion matid becoming a chromosome.and the amnion, the membranes that surround thefetus. Chorioamnionitis usually is associated with a chromatography, gas An automated techniquebacterial infection. This may be due to bacteria for separating mixtures of substances in which theascending from the mother’s genital tract into the mixture to be analyzed is vaporized and carried by
chromatopsia 84an inert gas through a special column and thence to chromosome, metaphase A chromosome ata detection device. the stage in the cell cycle at which it is most con- densed, easiest to see by itself, and therefore easiestchromatopsia Colored vision. A condition in to study. Metaphase chromosomes are often chosenwhich objects appear abnormally colored to the for karyotyping and chromosome analysis.viewer. chromosome, prophase A chromosome at achromosome A carrier of genetic information stage before metaphase in the cell cycle, when thethat is visible under an ordinary light microscope. chromosomes are long and often tangled like a ballEach human chromosome has two arms, the p of twine. Prophase chromosomes may be selected(short) arm and the q (long) arm. These arms are for analysis via resolution chromosome bandingseparated from each other only by the centromere, when it is important to detect minute details.which is the point at which the chromosome isattached to the spindle during cell division. The 3 chromosome, sex The X or Y chromosome inbillion base pairs in the human genome are organ- humans. (Some other species have other sex chro-ized into 24 chromosomes. All genes are arranged mosomes.)linearly along the chromosomes. Generally thenucleus of a human cell contains two sets of chro- chromosome, X The sex chromosome foundmosomes—one set given by each parent. Each set twice in normal females and once, along with a Yhas 23 single chromosomes: 22 autosomes and an chromosome, in normal males. The complete chro-X or a Y sex chromosome. (A normal female has a mosome complement (consisting of 46 chromo-pair of X chromosomes; a male has an X and Y somes, including the 2 sex chromosomes) is thuspair.) A chromosome contains roughly equal parts conventionally written as 46,XX for chromosomallyof protein and DNA. The chromosomal DNA con- normal females and 46,XY for chromosomally nor-tains an average of 150 million nucleotide building mal males. The X chromosome not only determinesblocks, called bases. DNA molecules are among the gender but also carries the genetic code for manylargest molecules now known. essential functions in both males and females.chromosome, acentric A fragment of a chro- chromosome, Y The sex chromosome found inmosome that lacks a centromere, so that the chro- normal males, together with an X chromosome.mosome is lost when the cell divides. Once thought to be a genetic wasteland, the Y chro- mosome is now known to contain at least 20 genes.chromosome, acrocentric A chromosome that Some of these genes are unique to the Y chromo-has its centromere located near one end of the some, including the male-determining gene andchromosome. Humans have five pairs of acrocentric male fitness genes that are active only in the testischromosomes. Down syndrome is due to an extra and that are thought to be responsible for the for-acrocentric chromosome (chromosome 21). mation of sperm. Other genes on the Y chromosome have counterparts on the X chromosome, are activechromosome, autosomal Any chromosome in many body tissues, and play crucial “housekeep-other than a sex chromosome (X or Y chromo- ing” roles within cells.some). Also known as an autosome. chromosome complement The whole set ofchromosome, dicentric A chromosome that is chromosomes for a species. In humans, the normalabnormal in that it has two centromeres rather than chromosome complement consists of 46 chromo-one. Because the centromere is essential for chro- somes, including the 2 sex chromosomes. Alsomosome division, a dicentric chromosome is pulled known as the karyotype.in opposite directions when the cell divides. Thiscauses the chromosome to form a bridge and then chromosome disorder An abnormal conditionbreak and be unstable. due to something unusual in an individual’s chromo- somes. For example, Down syndrome is a chromo-chromosome, marker An abnormal chromo- some disorder caused by the presence of an extrasome that is distinctive in appearance but not fully copy of chromosome 21, and Turner syndrome isidentified. A marker chromosome is not necessarily most often due to the presence of only a single sexa marker for a specific disease or abnormality, but chromosome: one X chromosome.it can be distinguished under the microscope fromall the normal human chromosomes. For example, chromosome inversion A condition in which athe fragile X (FRAXA) chromosome was once called chromosome segment is clipped out, turned upsidethe marker X. down, and reinserted back into the chromosome. A
85 chronic peritonitischromosome inversion can be inherited from one emphysema. In comparison, an acute illness is ofor both parents, or it may be a mutation that short duration. See also acute.appears in a child whose family has no history ofchromosome inversion. An inversion can be “bal- chronic fatigue syndrome A debilitating andanced,” meaning that it has all the genes that are complex disorder characterized by profound fatiguepresent in a normal chromosome; or it can be that lasts 6 months or longer, is not improved by“unbalanced,” meaning that genes have been bed rest, and may be worsened by physical or men-deleted (lost) or duplicated. A balanced inversion tal activity. Abbreviated CFS. Persons with CFS mostcauses no problems. An unbalanced inversion is often function at a substantially lower level of activ-often associated with problems such as develop- ity than they were capable of before the onset of themental delay, mental retardation, and birth defects. illness. In addition to these key defining character- istics, patients report various nonspecific symp-chromosome inversion, paracentric A type of toms, including weakness, muscle pain, impairedchromosome rearrangement in which a chromoso- memory and/or mental concentration, insomnia,mal segment that does not include the centromere and postexertional fatigue lasting more than 24(and is therefore paracentric) is snipped out of a hours. In some cases, CFS can persist for years. Thechromosome, inverted, and inserted back into the cause or causes of CFS have not been identified, andchromosome. The feature that makes it paracentric no specific diagnostic tests are available. Moreover,is that both breaks are on the same side of the cen- because many illnesses have incapacitating fatiguetromere, so that the centromere is not involved in as a symptom, care must be taken to exclude otherthe rearrangement. known and often treatable conditions before a diag- nosis of CFS is made. Also known as chronic fatiguechromosome inversion, pericentric A basic and immune dysfunction syndrome (CFIDS) andtype of chromosome rearrangement in which a seg- myalgic encephalomyelitis (ME).ment that includes the centromere (and is thereforepericentric) is snipped out of a chromosome, chronic illness An illness that lasts 3 months orinverted, and inserted back into the chromosome. more.The feature that makes it pericentric is that thebreaks are on both sides of the centromere. chronic leukemia Cancer of the blood cells that progresses slowly, as opposed to acute leukemia,chromosome map The chart of the linear array which progresses rapidly. The two major types ofof genes on a chromosome. The Human Genome chronic leukemia are chronic lymphocyticProject contributes to the mapping of the human leukemia (CLL) and chronic myeloid leukemiachromosomes. See also Human Genome Project. (CML). See also leukemia, chronic phase of.chromosomes in multiple miscarriages chronic lymphocytic leukemia See leukemia,Chromosome abnormalities (such as deletions, chronic lymphocytic.additions, or translocations) that are responsiblefor causing miscarriages. A couple that has had chronic myeloid leukemia See leukemia,more than one miscarriage has about a 5 percent chronic myeloid.chance that one member of the couple is carryingan irregular chromosome that is responsible for the chronic obstructive lung disease Any disordermiscarriages. that persistently obstructs bronchial airflow. Abbreviated COLD. COLD mainly involves twochronic In medicine, lasting a long time. A related diseases: chronic bronchitis and emphy-chronic condition is one that lasts 3 months or sema. The obstruction is generally permanent andmore. Chronic diseases are in contrast to those that worsens over time. In asthma, there is also obstruc-are acute (abrupt, sharp, and brief) or subacute tion of airflow out of the lungs, but the obstruction(within the interval between acute and chronic). is usually reversible, and between asthma attacks, the flow of air through the airways is generally good.chronic arthritis, systemic-onset juvenile Also known as chronic obstructive pulmonary dis-See Still’s disease. ease (COPD).chronic bronchitis See bronchitis, chronic. chronic obstructive pulmonary disease See chronic obstructive lung disease.chronic disease A disease that persists for a longtime, typically 3 months or more. Examples of chronic peritonitis See peritonitis, chronic.chronic diseases include arthritis, diabetes, and
chronic phase 86chronic phase See leukemia, chronic phase of. circulation In medicine, the movement of fluid through the body in a regular or circuitous course.chronic tamponade See tamponade, chronic. The circulatory system, composed of the heart and blood vessels, functions to produce circulation.chronicity The state of being chronic, having a Heart failure is an example of a problem with cir-long duration. culation.Churg-Strauss syndrome A disease character- circulation, fetal The blood circulation in theized by inflammation of the blood vessels in persons fetus (an unborn baby). Before birth, blood fromwith history of asthma or allergy. The symptoms the fetal heart that is destined for the lungs isinclude fatigue, weight loss, inflammation of the shunted away from the lungs through a short vesselnasal passages, numbness, and weakness. The diag- called the ductus arteriosus and returned to thenosis is confirmed with a biopsy of involved tissue. aorta. When this shunt is open, it is said to be aTreatment involves stopping inflammation and sup- patent ductus arteriosus (PDA). The PDA usuallypressing the immune system. Also known as allergic closes at or shortly after birth, allowing blood togranulomatosis and allergic granulomatous angiitis. course freely to the lungs.chyme A predigested, acidified mass of food that circulatory Having to do with circulation, thepasses from the stomach into the small intestine. movement of fluid in a regular or circuitous course.Ci The abbreviation for a Curie, a unit of radioac- circulatory system The system that moves bloodtivity. See also Curie. through the body. The circulatory system is com- posed of the heart, arteries, capillaries, and veins.-cide Suffix indicating killing or killer, as in bac- This remarkable system transports oxygenatedtericide (a solution capable of killing bacteria). blood from the lungs to the heart and throughout the body via the arteries. The blood goes from theciliary neuralgia See cluster headache. arteries to the veins by passing through the capillar- ies. Then the blood that has been depleted of oxygencircadian Refers to events occurring within thespan of a full 24-hour day, as in a circadian clock. by the body is returned to the lungs and heart via the veins. See also artery; blood; heart; lung; respira-circadian clock An internal time-keeping system tory system; vein.in all organisms. Changes in the external environ-ment, particularly in the light–dark cycle, train this circumcision, female The excision (removal)biologic clock. When environmental conditions are of part or all of the external female genitalia, includ- ing the clitoris, and sometimes extending to theconstant, rhythms driven by the circadian clock fol- labia. Female circumcision is practiced in somelow a nearly perfect 24-hour pattern. The human parts of the Middle East and Africa, particularlycircadian clock regulates many daily activities, such Sudan, and it is viewed with disfavor in other partsas sleep and waking. When a person doesn’t follow of the world. Also known as female genital mutila-these natural rhythms, or when the external environ- tion. See also clitoridectomy.ment strays from its usual rhythm (as occurs in thelong nights and short days of deep winter), the cir- circumcision, male Surgery that removes thecadian clock must readjust. Rapid environmental protective ring of loose skin (foreskin) that normallychanges and problems with circadian clock adjust- covers the glans of the penis. Circumcision datesment are among the causes of jet lag, problems that back to prehistoric times, and it may be performedaffect shift workers, some types of sleep disorders, for religious or cultural reasons, or to promoteand bipolar disorders, particularly seasonal affective cleanliness. Newborn circumcision decreases thedisorder. Certain genes serve to set and control the risk of urinary tract infections and lowers the risk ofcircadian clock. See also bipolar disorder; jet lag; sexually transmitted diseases, including HIV. It alsoseasonal affective disorder; sleep disorder. diminishes the risk for cancer of the penis and lessens the risk for cancer of the cervix in sexualcircinate balanitis See balanitis, circinate. partners.circle of Willis A critical arterial circle at thebase of the brain. The circle of Willis receives all the cirrhosis Liver disease characterized by irre- versible scarring. Alcohol and viral hepatitis, includ-blood that is pumped up the two internal carotid ing both hepatitis B and hepatitis C, are among thearteries that come up the front of the neck. All the many causes of cirrhosis. Cirrhosis can cause yel-principal arteries that supply the two halves of the lowing of the skin (jaundice), itching, and fatigue.brain (hemispheres) branch off from the circle of Diagnosis is suggested by physical examination andWillis.
87 clinicalblood tests, and it can be confirmed by liver biopsy. clavicle See collarbone.Complications of cirrhosis include mental confu-sion, coma, fluid accumulation (ascites), internal clavus See corn.bleeding, and kidney failure. Treatment is designedto limit any further damage to the liver and to pre- clay-shoveler’s fracture See fracture, clay-vent complications. Liver transplantation is becom- shoveler’s.ing an important option for patients with advancedcirrhosis. cleft lip A fissure in the upper lip that is due to failure of the left and right sides of the fetal lip tis-cirrhosis, primary biliary A scarring liver dis- sue to fuse, an event that should take place by 35ease caused by an abnormality of the immune sys- days of fetal age. Cleft lip can be on one side only ortem. Small bile ducts within the liver become on both sides. Because failure of lip fusion caninflamed and obliterated from scarring. Backup of impair the subsequent closure of the palatal shelves,bile causes intense skin itching and yellowing of the cleft lip often occurs in association with cleft palate.skin (jaundice). Lack of bile decreases absorption It is one of the most common physical birth defects,of calcium and vitamin D, leading to osteoporosis. and it can be corrected with surgery.See also cirrhosis. cleft palate An opening in the roof of the mouthcitrulline antibody An immune protein (anti- due to a failure of the palatal shelves to come fullybody) that binds to a non-standard amino acid, cit- together from either side of the mouth and fuse dur-rulline, which is formed by removing amino groups ing the first months of development as an embryo.from the natural amino acid, arginine. Citrulline The opening in the palate permits communicationantibody is present in the blood of many patients between the nasal passages and the mouth. Surgerywith rheumatoid arthritis. It is used in the diagnosis is needed to close the palate. Cleft palate can occurof rheumatoid arthritis when evaluating patients alone or in association with cleft lip.with unexplained joint inflammation. Also known asanti-citrulline antibody, anti-cyclic citrullinated pep- cleft uvula A common minor anomaly in whichtide antibody, CCP antibody, and anti-CCP antibody. the uvula (the tissue that hangs down at the back of the palate) is cleft, or parted by a fissure. PersonsCl The chemical symbol for the element chlorine. with a cleft uvula should not have their adenoids removed because without the adenoids they cannotclap Slang term for gonorrhea. See gonorrhea. achieve proper closure between the soft palate and pharynx while speaking, and they will developclasped thumbs and mental retardation See hypernasal speech. Also known as bifid uvula.adducted thumbs. cleidocranial dysostosis A genetic disorder ofclaudication Limping. From the Latin claudi- bone development that is characterized by absent orcare, which means “to limp.” The Roman emperor incompletely formed collarbones and cranial andClaudius was so named because he limped, proba- facial abnormalities that may include square skull,bly because of a birth defect. late closure of the sutures of the skull, late closure of the fontanels, low nasal bridge, delayed eruptionclaudication, intermittent Pain in the calf that of the teeth, and abnormal permanent teeth. A childcomes and goes, typically felt while walking, and with this disorder can bring his or her shouldersusually subsiding with rest. Intermittent claudica- together, or nearly so. The gene for cleidocranialtion can be due to temporary artery narrowing due dysostosis has been found on chromosome 6 into vasospasm, permanent artery narrowing due to band p21. Also known as cleidocranial dysplasiaatherosclerosis, or complete occlusion of an artery and craniocleidodysostosis.to the leg. The prognosis is generally favorablebecause the condition often stabilizes or improves click-murmur syndrome See mitral valvewith time. Walking regularly can sometimes prolapse.increase the distance that the patient can walk with-out symptoms. Drugs may be prescribed for man- climacteric 1 Menopause in women. 2 Theagement. If conservative therapy is inadequate and time corresponding to menopause in the life ofclaudication is severe and persistent, correction of men.the narrowing in the affected artery with surgery,such as bypass grafting, or interventional radiology, clinical 1 Having to do with the examination andsuch as balloon angioplasty might be suggested. treatment of patients. 2 Applicable to patients. The term comes from the French “clinique” (at theclaudication, venous Limping and/or pain bedside).resulting from inadequate venous drainage.
clinical cytogenetics 88clinical cytogenetics The application of chro- CLL Chronic lymphocytic leukemia. Seemosome analysis to clinical medicine. For example, leukemia, chronic lymphocytic.clinical cytogenetic testing is done to look for anextra chromosome 21 in a child who is suspected of clone 1 A replica. For example, a clone can behaving Down syndrome. made of a group of bacteria or a macromolecule such as DNA. 2 A group of cells derived from aclinical depression Depressed mood that meets single ancestral cell. 3 An individual developedthe DSM-IV criteria for a depressive disorder. The from a single somatic (nongerm) cell from a par-term clinical depression is commonly used to ent, representing an exact replica of that parent.describe depression that is a type of mental ill-ness—not a normal, temporary mood caused by clone, recombinant A clone that containslife events or grieving. recombinant DNA molecules.clinical disease A disease that has recognizable clone bank See genomic library.clinical signs and symptoms, as distinct from a sub-clinical illness, which lacks detectable signs and cloning The process of creating a geneticallysymptoms. Diabetes, for example, can be a subclin- identical copy.ical disease for some years before becoming a clin-ical disease. cloning, cell The process of producing a group of cells (clones), all genetically identical, from aclinical research trial A study that is intended single ancestral cell.to evaluate the safety and effectiveness of medica-tions or medical devices by monitoring their effects cloning, DNA The use of DNA manipulation pro-on large groups of people. Studies may be con- cedures to produce multiple copies of a single geneducted by government health agencies (such as the or segment of DNA.National Institutes of Health [NIH]), researchersaffiliated with hospital or university medical pro- cloning, therapeutic See therapeutic cloning.grams, independent researchers, or individuals Clostridium difficile A bacterium that is one offrom private industry. Usually volunteers are the most common causes of infection of the colon inrecruited, although in some cases research partici- the US. Patients taking antibiotics are at risk ofpants may be paid. For some patients, clinical becoming infected with C. difficile as antibiotics canresearch trials represent an avenue for receiving disrupt the normal bacteria of the bowel, allowingpromising new therapies that would not otherwise C. difficile to become established in the colon. Inbe available. Patients with difficult-to-treat or some people, a toxin produced by C. difficile causes“incurable” diseases may pursue participation in diarrhea, abdominal pain, severe inflammation ofclinical research trials if standard therapies are not the colon (colitis), fever, an elevated white bloodeffective. cell count, vomiting, and dehydration. In severelyclinical trial See clinical research trial. affected patients, the inner lining of the colon becomes severely inflamed (pseudomembranousclip A device used to hold something or things colitis) with the potential to perforate.together. For example, a surgical clip may be usedto prevent a blood vessel from bleeding into the Clostridium perfringens A bacterium that isbrain, or in a vasectomy to pinch together the sides the most common cause of gas gangrene, a lethalof the vas deferens. infection of soft tissue, especially muscle. C. per- fringens bacteria are toxin- and gas-producing bac-clitoridectomy The surgical excision (removal) teria. Before the introduction of antibiotics, aof the clitoris to reduce a woman’s ability to be sex- significant percentage of battlefield injuries wereually stimulated during intercourse. Also known as complicated by gas gangrene. C. perfringens alsofemale circumcision and female genital mutilation. causes food poisoning and a fulminant form ofSee also circumcision, female. bowel disease called necrotizing colitis. Formerly known as C. welchii.clitoris A small mass of erectile tissue in thefemale that is situated at the anterior apex of the Clostridium welchii See Clostridium perfrin-vulva, near the meeting of the labia majora (vulvar gens.lips). Like the penis, the clitoris is highly sensitive tostimulation during sex. The clitoris corresponds to clot-dissolving medication An agent such asthe penis in the male. plasminogen-activator (t-PA) or streptokinase that is effective in dissolving clots and reopening arteries.
89 coccyxFor example, clot-dissolving medications may be CNS prophylaxis Chemotherapy or radiationused in the treatment of heart attacks, to reestablish therapy to the central nervous system (CNS) as ablood flow to the heart muscle (myocardium). Also preventive treatment. CNS prophylaxis is given to killknown as thrombolytic agents. cancer cells that may be in the brain and spinal cord, even though no cancer has been detectedclubfoot A common malformation of the foot that there.is evident at birth. The foot is turned in sharply sothat the person seems to be walking on his or her coagulation, blood See blood coagulation.ankle. Clubfoot can sometimes be corrected with acombination of surgery, bracing, and physical ther- coal miner’s pneumoconosis See black lungapy. Also known as talipes equinovarus. disease.cluster An aggregation of cases of a disease or coarctation A narrowing, stricture, or constric-another health-related condition, such as a cancer, tion of an artery. The sides of the vessel at the pointbirth defect, or headaches, closely grouped in time of a coarctation appear to be pressed together.and place. See also cluster headache. coarctation of the aorta Congenital constric-cluster headache A distinctive episodic syn- tion of the aorta that impedes the flow of blooddrome of headaches. The most common cluster below the level of the constriction and increasesheadache pattern, acute cluster headache, is char- blood pressure above the constriction. Symptomsacterized by one to three short attacks of pain each may not be evident at birth but may develop as soonday around the eyes, clustered over a stretch of 1 to as the first week after birth, with congestive heart2 months, and followed by a pain-free period that failure or high blood pressure that can require earlyaverages 1 year. The other main pattern of cluster surgery. The outlook after surgery is favorable.headache, chronic or episodic cluster headache, is Some cases have been treated with balloon angio-characterized by the absence of sustained periods of plasty.remission, with pain occurring out of the blue oremerging several years after an episodic pattern. coated stent A tiny cage to prop open an arteryCluster headache is different and distinct from and prevent it from closing again, that is coated withmigraine, although the underlying mechanisms are a drug. The stent is inserted into a coronary artery,similar. For example, propranolol is effective in usually just after an angioplasty has been done, totreating migraine but not in treating cluster keep open the vessel. The stent slowly releases theheadache, whereas lithium is beneficial for cluster drug with which it is coated. Coated stents reduceheadache but not migraine. Also known as ciliary the risk of artery re-narrowing (restenosis) afterneuralgia, erythroprosopalgia, histamine cephalgia, angioplasty. Also known as a medicated stent, drug-migrainous neuralgia, Raeder syndrome, coated stent, drug-eluting stent, eluting stent.sphenopalatine neuralgia, and vidian neuralgia. cocaine A substance derived from the leaves ofcluttering A speech disorder characterized by the coca plant that is a bitter, addictive substancethe unwanted repetition of entire words. It resem- formerly used as an anesthetic. Safer anestheticsbles stuttering, in which only sounds or parts of than cocaine were developed in the 20th century,words are repeated. See also speech disorder. although it is still used as an injectable anesthetic by some dentists. Synthetic alternatives, such as pro-cM Centimorgan. caine, are used far more widely. Tragically, cocaine is a highly addictive and destructive street drug.CME Continuing medical education, educationthat physicians are required to obtain in order to cocci The plural of coccus.earn CME credits to retain their medical licenses.They may do so by taking courses, attending med- coccus A bacterial cell that has the shape of aical conferences where they learn about new devel- sphere. Coccus is part of the name of a number ofopments, or by reading and taking tests. bacteria, such as enterococcus, meningococcus, pneumococcus, staphylococcus, and streptococcus.CML Chronic myeloid leukemia. See leukemia,chronic myeloid. coccygeal vertebrae The three to five (the aver- age number is four) rudimentary vertebrae thatCNA Certified nurse aide. See nurse assistant. make up the coccyx.CNS Central nervous system. coccyx The small tail-like bone at the bottom of the spine, very near the anus. It is the lowest part of the spinal column. Also known as tailbone.
cochlear implant 90cochlear implant A device that is surgically nifying scope to look at the front of the eye whereplaced (implanted) within the inner ear to help a the epithelial basement membrane is seen as abnor-person with a certain form of deafness to hear. mal. The disorder is usually without symptoms.Cochlear implants rarely cure severe or profound However, about 1 patient in 10 has recurrent ero-deafness, but they can help some hearing-impaired sion of the cornea that generally begins after age 30.people to distinguish the sounds of language clearly Also known as epithelial basement corneal dystro-enough to participate in a verbal environment. For phy and map-dot-fingerprint type corneal dystrophychildren who are congenitally deaf (born deaf), a and microcystic corneal dystrophy.cochlear implant can markedly increase a pre-school child’s chances of being able to function Cogan syndrome A rare form of artery inflam-effectively in mainstream school classes. mation (arteritis) of unknown cause that affects the ear. Cogan syndrome causes problems of hearingcockroach allergy A condition that manifests as and balance and also inflammation of the corneaan allergic reaction when one is exposed to cock- and often fever, fatigue, and weight loss. Joint androach allergens, tiny protein particles shed or muscle pains can also be present. Less frequently,excreted by cockroaches. Asthma can be triggered the arteritis can involve blood vessels elsewhere inby exposure to these cockroach allergens. See also the body, as in the skin, kidneys, nerves, and otherallergy. tissues and organs. Cogan syndrome can lead to deafness or blindness. Treatment is directed towardcode, genetic The instructions in a gene that tell stopping the inflammation of the blood vessels.the cell how to make a specific protein. A, T, G, and Cortisone-related medications, such as prednisone,C are the “letters” of the DNA code and represent are often used. Severe disease can require immuno-the chemicals adenine, thymine, guanine, and cyto- suppression medications, such as cyclophos-sine, respectively. These make up the nucleotide phamide.bases of DNA. Each gene’s code combines these fourchemicals in various ways to spell out three-letter cognition The process of knowing. Cognition“words” that specify which amino acid is needed at includes both awareness and judgment.every step in making a protein. The discovery of thegenetic code ranks as one of the premiere events of cognitive Having to do with thought, judgment,biology and medicine. or knowledge.code blue An emergency situation announced in cognitive behavior therapy A therapeutic prac-a hospital or institution in which a patient is in car- tice that helps patients recognize and remedy dys-diopulmonary arrest, requiring a team of providers functional thought patterns. One characteristic(sometimes called a “code team”) to rush to the technique is exposure and response prevention, inspecific location and begin immediate resuscitative which a patient with a phobia deliberately exposesefforts. himself or herself to the feared situation, gradually decreasing the panic response. Cognitive behaviorcode pink A hospital or institution alert to secu- therapy is used to treat obsessive-compulsive disor-rity that a baby is missing from the hospital nursery. der, panic disorder, and other biologically based psychiatric illnesses, often in combination withcodon A set of any three adjacent bases in DNA or medication. Evidence gathered from brain scansRNA. There are 64 different codons, of which 61 indicates that over time this therapy can sometimesspecify the incorporation of an amino acid into a create actual changes in brain and neurotransmitterpolypeptide chain; the remaining 3 are stop codons, function. Abbreviated CBT.which signal the ends of polypeptides. cognitive disability A broad term used tocoenzyme A substance that enhances the action describe such diverse conditions as mental retarda-of an enzyme to mediate and speed a chemical reac- tion, thought disturbances, and neurological condi-tion. A number of the water-soluble vitamins, such tions that chronically affect a certain type ofas vitamins B1, B2, and B6, serve as coenzymes. See perception or mental ability.also enzyme. cognitive disturbance Disruption of one’s abil-Cogan corneal dystrophy A disorder in which ity to think logically.the cornea shows grayish fingerprint lines, geo-graphic map-like lines, and dots (or microcysts). cognitive dulling Loss of mental faculties; diffi-These lines and dots can be seen on examination culty in thinking logically or quickly. Cognitivewith a slit-lamp, which focuses a high-intensity light dulling can occur due to a medical condition or asbeam through a slit while the examiner uses a mag- a side effect of medication.
91 colitis, Crohn’scognitive science The study of the mind. cold sore A small sore located on the face or inCognitive science is an interdisciplinary science that the mouth that causes pain, burning, or itchingdraws on many fields, including neuroscience, psy- before bursting and crusting over. Common loca-chology, philosophy, computer science, artificial tions for cold sores are the lips, chin, cheeks, andintelligence, and linguistics. The purpose of cogni- nostrils. Cold sores more rarely appear on the gumstive science is to develop models that help explain and the roof of the mouth. Cold sores are caused byhuman perception, thinking, and learning with the herpes simplex type 1 virus, which lies dormant inpremise that the mind is an information processor. the body and is reawakened by factors such asThis processor receives, stores, retrieves, trans- stress, sunburn, or fever from a wide range of infec-forms, and transmits information. The information tious diseases, including colds. Sunscreen (SPF 15and the corresponding information processes can or higher) on the lips prevents recurrences of her-be studied as patterns. pes due to sunburn. The virus is highly contagious when fever blisters are present. It is spread by phys-cohort In a clinical research trial, a group of ical contact, such as kissing. Also known as labialstudy participants or patients. herpes, febrile herpes, and fever blister.coinsurance See copayment. colectomy An operation to remove all or part of the colon (large intestine). In a partial colectomy,coitus Sexual intercourse. the surgeon removes only part of the colon. The bowel is then reconnected or an opening of thecoitus interruptus Sexual intercourse in which, bowel (ostomy) is created on the abdominal wall toas a birth-control measure, the male attempts to allow the contents of the bowel to exit from thewithdraw the penis before ejaculation. It is not usu- body. Colectomy may be needed for treatment ofally an effective means of birth control because diverticulitis, benign polyps of the colon, and can-sperm are present in preejaculate fluid produced cer of the colon.during intercourse. See also birth control. colic A cause of crampy abdominal pain in earlycolchicine A plant substance that is used in clin- infancy. Colic is a common condition, occurring inical medicine for the treatment of the inflammation, about 1 in 10 babies. An infant with colic is irrita-such as from gouty arthritis, and in the laboratory ble, cries, and often has a rigid abdomen and drawsto arrest cells during cell division by disrupting the up its legs. Overfeeding, undiluted juices, food aller-spindles so that their chromosomes can be visual- gies, and stress can aggravate colic. Colic usuallyized. lasts from early infancy to the third or fourth month of age. Treatment can include dietary changes, care-COLD Chronic obstructive lung disease. fully measured feedings, and extra burping. Parents should not assume that new abdominal pain andcold, common A contagious viral upper respira- loud crying in their baby are colic. It is importanttory tract infection. The common cold can be for the baby to be seen by a physician to rule outcaused by many different types of viruses, and the more serious conditions.body can never build up resistance to all of them.For this reason, colds are a frequent and recurring colitis Inflammation of the colon (large intes-problem. Going out into cold weather has no effect tine). There are many forms of colitis, includingon causing a cold. Antibiotics do not cure or amebic, Crohn’s, infectious, pseudomembranous,shorten the duration of the illness. spastic, and ulcerative.cold, June See hay fever. colitis, amebic Inflammation of the intestine, with ulcers in the colon, due to infection with ancold, summer See allergic rhinitis. ameba called Entamoeba histolytica. This parasitecold injury An injury caused by exposure to can be transmitted to humans via contaminatedextreme cold that can lead to loss of body parts and water and food. Symptoms, which include diarrhea,even to death. Examples of cold injury are chilblain, indigestion, nausea, and weight loss, can begintrench foot, and frostbite. Cold injury occurs with shortly after infection, or the ameba may live in theand without freezing of body tissues. The young and gastrointestinal tract for months or years beforethe elderly are especially prone to cold injury, and symptoms erupt. Amebic colitis can be treated withalcohol consumption increases the risk of cold medication, including emetine and antibiotics. Seeinjury. It is important not to thaw an extremity if also amebic dysentery; amebiasis.there is a risk of it refreezing. The extremity shouldbe protected from trauma and gradually rewarmed. colitis, Crohn’s Crohn’s disease affecting the colon. Also known as granulomatous colitis. See also Crohn’s disease.
colitis, granulomatous 92colitis, granulomatous See colitis, Crohn’s. collarbone A horizontal bone above the first rib that makes up the front part of the shoulder. Alsocolitis, pseudomembranous Severe inflamma- known as the clavicle, the collarbone links thetion of the inner lining of the colon, usually due to breastbone (sternum) with the scapula, a triangularthe Clostridium difficile bacterium. Patients taking bone in the back of the shoulder. One end of theantibiotics are at particular risk of becoming collarbone connects to the sternum, forming oneinfected with C. difficile because the natural bacte- side of the sternoclavicular joint. The other end ofria of the bowel can usually prevent proliferation of the collarbone connects to the scapula, there form-C. difficile, but they are disrupted by antibiotics. A ing one side of the acromioclavicular joint.toxin produced by C. difficile causes colitis symp-toms, including diarrhea, abdominal pain, and collateral 1 In anatomy, a subordinate or acces-severe inflammation. Rarely, the walls of the colon sory part. 2 A side branch, as of a blood vessel orwear away and holes develop (colon perforation), nerve. After a coronary artery occlusion, collateralwhich can lead to a life-threatening infection of the vessels often develop to shunt blood around theabdomen. See also Clostridium difficile. blockage.colitis, spastic See irritable bowel syndrome. collateral knee ligament, lateral A ligament that straps the outside of the knee joint and provides sta-colitis, ulcerative A bowel disease that is char- bility and strength to the knee joint. Abbreviated LCL.acterized by inflammation with ulcer formation inthe lining of colon (large intestine). Its cause is collateral knee ligament, medial A ligamentunknown. The end of the colon (the rectum) is gen- on the inner side of the knee joint. The medial col-erally involved. When limited to the rectum, the dis- lateral knee ligament adds stability and strength toease is called ulcerative proctitis. The inflammation the knee joint. Abbreviated MCL.may extend to varying degrees into the upper partsof the colon. When the entire colon is involved, it is colon The long, coiled, tubelike organ thatreferred to as pancolitis or universal colitis. removes water from digested food. The remainingSymptoms include intermittent rectal bleeding, material, solid waste called stool, moves through thecrampy abdominal pain, and diarrhea. Many colon to the rectum and leaves the body through thepatients experience long remissions, even without anus. Also known as large bowel and large intestine.medication. Ulcerative colitis may mysteriouslyresolve after a long history of symptoms. Direct visu- colon cancer See cancer, colon.alization (via sigmoidoscopy or colonoscopy) andbiopsy of the lining of the bowel is the most accurate colon cancer prevention Measures taken todiagnostic test. Treatment of ulcerative colitis prevent the formation of colon cancer. Colorectalinvolves medications and/or surgery; changes in cancer can run in families. The risk of colon cancerdiet can sometimes help. is increased for a person whose immediate family member (parent, sibling, or child) had colorectalcolitis, universal Ulcerative colitis that involves cancer. It is increased further for a person who hasthe entire colon (large intestine). had more than one such relative with colorectal cancer or a family member who has developedcollagen The principal protein of the skin, ten- colon cancer earlier than 55 years of age.dons, cartilage, bone, and connective tissue. Individuals to whom any of these circumstancesCollagen is an essential part of the framework of the apply should undergo colonoscopy every 3 years,design of our various body tissues. starting at an age that is 7 to 10 years younger than when the youngest family member with colon can-collagen disease A disease that damages colla- cer was diagnosed.gen or other components of connective tissue. Forexample, dermatomyositis and systemic lupus ery- colon polyp A benign tumor of the large intes-thematosus are collagen diseases. tine. Benign polyps do not invade nearby tissue or spread to other parts of the body. Benign polyps cancollagen injection The practice of injecting col- easily be removed during colonoscopy and are notlagen into a part of the face or body (often the lips) life threatening. If benign polyps are not removedto make it larger. The effects are long-lasting but not from the large intestine, they can become malignantpermanent. Collagen injections are usually done by (cancerous) over time. Most cancers of the largeplastic surgeons. intestine are believed to have developed from polyps.collapsed lung See atelectasis. colonic irrigation See irrigation of the colon.
93 common coldcolonoscope A flexible, lighted instrument used (stoma) to permit sanitary collection and disposalto view the inside of the colon. of bodily wastes.colonoscopy A procedure whereby a physician colostrum A sticky white or yellow fluid secretedinserts a viewing tube (colonoscope) into the rec- by the breasts during the second half of pregnancytum for the purpose of inspecting the colon. During and for a few days after birth, before breast milkcolonoscopy, polyps can be removed, bleeding can comes in. It is high in protective antibodies thatbe cauterized, and a biopsy can be performed if boost the newborn’s immune system.abnormal areas of the colon are seen. colpo- Prefix referring to the vagina.colony-stimulating factor A laboratory-madeagent that is similar to substances in the body that colpopexy The use of stitches to bring a dis-stimulate the production of blood cells. Abbreviated placed vagina back into position against the abdom-CSF. Treatment with CSF can help blood-forming tis- inal wall.sue recover from the effects of chemotherapy andradiation therapy. colpoptosis A condition in which the vagina has dropped from its normal position against thecolorblindness The inability to perceive colors abdominal wall.in a normal fashion. The most common forms ofcolorblindness are inherited as sex-linked (X- colporrhaphy Surgical repair of the vagina.linked) recessive traits. Females are carriers andmales are affected. As a result, approximately 1 in 8 colposcopy A procedure in which a lighted mag-males is colorblind, compared to fewer than 1 in nifying instrument called a colposcope (or100 females. The most common form of color- vaginoscope) is used to examine the vagina andblindness is red–green. The second most common cervix.form is blue–yellow. The most severe form of color-blindness is achromatopsia, the inability to see any colpotomy A surgical incision in the vagina.color. Testing for colorblindness is commonly per- coma A state of deep, unarousable unconscious-formed along with other types of vision screening. ness. A coma may occur as a result of head trauma,See also monochromatism. disease, poisoning, or numerous other causes.colorectal Related to the colon and/or rectum. Coma states are sometimes graded based on the absence or presence of reflexive responses to stim-colorectal cancer See cancer, colon. uli.colostomy An artificial exit from the colon cre- comedo The primary sign of acne, consisting of aated to divert waste through a hole in the colon and widened hair follicle filled with keratin skin debris,through the wall of the abdomen. A colostomy is bacteria, and sebum (oil). A comedo may be closedcommonly performed by severing the colon and or open. A closed comedo (called a whitehead) hasthen attaching the end leading to the stomach to the an obstructed opening to the skin and may ruptureskin, through the wall of the abdomen. At the exte- to cause a low-grade inflammatory skin reaction inrior opening (stoma), a bag can be attached for the area. An open comedo (called a blackhead) haswaste removal. The end of the colon that leads to the a wide opening to the skin and is capped with arectum is closed off and becomes dormant (known blackened mass of skin debris.as a Hartmann colostomy). There are other types ofcolostomy procedures. Usually a colostomy is per- comedones The plural of comedo. See alsoformed because of infection, blockage, cancer, or in comedo.rare instances, severe trauma of the colon. comminuted fracture See fracture, commin-colostomy, iliac A colostomy in which the exte- uted.rior opening (stoma) is located on the lower-left common bile duct The duct that carries bileside of the abdomen. from the gallbladder and liver into the duodenumcolostomy, transverse A colostomy in which the (upper part of the small intestine). The commonexterior opening (stoma) is located on the upper bile duct is formed by the junction of the cystic duct,abdomen. from the gallbladder, and the common hepatic duct, from the liver.colostomy bag A removable, disposable bag thatattaches to the exterior opening of a colostomy common cold See cold, common.
communicable disease 94communicable disease A disease caused by an complication In medicine, an unanticipatedinfectious organism. problem that arises following, and is a result of, a procedure, treatment, or illness. A complication iscommunication disorder A disorder of the so named because it complicates the situation.speech apparatus and/or of the mental facultiesused to speak or communicate by other means. compound fracture See fracture, compound.Treatment includes speech therapy and other inter-ventions, as appropriate, for the underlying condi- compound microscope A microscope that con-tion. See also aphasia; apraxia of speech; sists of two microscopes in series, the first servingarticulation disorder; autism; cluttering; speech as the ocular lens (close to the eye) and the seconddisorder; stuttering. serving as the objective lens (close to the object to be viewed).comorbid Occurring together. For example, if aperson has both Crohn’s disease and stomach compress Cloth or another material appliedulcers, these are comorbid conditions. under pressure to an area of the skin and held in place for a period of time. A compress can be anycompassionate use A term used in the US for a temperature, and it can be dry or wet. It may also bemethod of providing experimental treatments, gen- impregnated with medication or an herbal remedy.erally for very ill individuals who have no other Most compresses are used to relieve inflammation.treatment options, prior to final FDA approval foruse in humans. compression fracture See fracture, compres- sion.complementary medicine A group of diagnos-tic and therapeutic disciplines that are used computed tomography scan See CAT scan.together with conventional medicine. An example ofa complementary therapy is using aromatherapy to computerized axial tomography scan Seehelp lessen a patient’s discomfort following surgery. CAT scan.Complementary medicine is traditionally not taughtor used in Western medical schools or hospitals. conception 1 The union of a sperm and an eggComplementary medicine includes a large number to create the first cell of a new organism. The termof practices and systems of health care that, for a conception has also been used to imply the implan-variety of cultural, social, economic, or scientific tation of the blastocyst, the formation of a viablereasons, have not been adopted by mainstream zygote, and the onset of pregnancy. 2 Related toWestern medicine. See also alternative medicine; the formulation or understanding of an idea. Seeconventional medicine. also pregnancy.complete androgen insensitivity syndrome concussion A traumatic injury to soft tissue, usu-An older term for the complete androgen insensitiv- ally the brain, as a result of a violent blow, shaking,ity syndrome, a genetic disorder that makes XY or spinning. A brain concussion can cause immedi-fetuses insensitive (unresponsive) to androgens ate but temporary impairment of brain functions,(male hormones). Instead, they are born looking such as thinking, vision, equilibrium, and con-externally like normal girls. Internally, there is a sciousness. After a person has had a concussion, heshort blind-pouch vagina and no uterus, fallopian or she is at increased risk for recurrence.tubes, or ovaries. There are testes in the abdomen Moreover, after a person has several concussions,or the inguinal canal. The complete androgen less of a blow can cause injury, and the person caninsensitivity syndrome is usually detected at puberty require more time to recover.when a girl should but does not begin to menstru-ate. The gene for the syndrome is on the X chromo- conditioning 1 Exercise and practice to build upsome and codes for the androgen receptor (also the body for either improved performance, as incalled the dihydrotestosterone receptor). There are physical therapy, or in preparation for sports per-also partial androgen insensitivity syndromes. formance. 2 The development of certain pre- dictable behavior as a result of repetitive activity orcomplete blood count See CBC. exposure.complete hysterectomy See hysterectomy, conditioning, Pavlovian Use of a system oftotal. rewards and punishments to influence behavior. Named after the Russian physiologist Ivan Petrovichcomplete syndactyly See syndactyly, complete. Pavlov, who conditioned dogs to respond in what proved to be a predictable manner by giving them rewards.
95 congenital malformationcondom A barrier method of contraception con- cone cell A light-sensitive cell in the retina of thesisting of a sheath made of latex, lambskin, or other eye. Cone cells absorb light and are essential formaterial that collects semen and thereby prevents distinguishing colors.conception. There are both male and female con-doms. When not specified, the term condom usually congenital A condition that is present at birth,refers to a male condom. See also barrier method; whether or not it is inherited.birth control; condom, female; condom, male. congenital aganglionic megacolon Seecondom, female A sheath made of plastic or Hirschsprung’s disease.latex that is anchored outside the vagina and linesthe interior of the vagina. It collects semen, pre- congenital clasped thumbs with mental retar-venting the semen from reaching the cervix, and dation See adducted thumbs.thereby preventing conception. It also providessome protection against sexually transmitted dis- congenital defect A birth defect.eases, including the HIV virus. See also barriermethod; birth control. congenital dislocation of the hip See congen- ital hip dislocation.condom, male A sheath made of latex, lambskin,or other material that is placed over the erect penis congenital heart disease A malformation of thebefore penetration to collect semen, preventing the heart, aorta, or other large blood vessels that is thesemen from reaching the cervix, and thereby pre- most frequent form of major birth defect in new-venting conception. When used consistently, a con- borns. Abbreviated CHD. There are many types ofdom is a reasonably reliable method of CHD, including atrial septal defect (ASD), ventricu-contraception, especially if it is combined with the lar septal defect (VSD), pulmonary (valvular)use of a spermicide or a female barrier method (but stenosis, aortic stenosis, coarctation of the aorta,not a female condom). Latex condoms also provide Tetralogy of Fallot, and transposition of the greatsome protection against sexually transmitted dis- arteries. Much of the practice of pediatric cardiol-eases, including HIV, but lambskin condoms do not ogy consists of the diagnosis and treatment of CHD.protect against HIV. A condom can be used only Also known as congenital heart defect, congenitalonce. See also barrier method; birth control. heart malformation, congenital cardiovascular dis- ease, congenital cardiovascular defect, and congen-conduction system, cardiac See cardiac con- ital cardiovascular malformation.duction system. congenital hemolytic jaundice See spherocy-condyloma Wartlike growths around the anus, tosis, hereditary.vulva, or glans penis. There are three major types ofcondyloma, each of which is sexually transmitted: congenital hip dislocation One of the mostcondyloma acuminatum (warts around the vulva), common birth defects, characterized by an abnor-condyloma latum (a form of secondary syphilis), mal formation of the hip joint in which the ball atand condyloma subcutaneum (also known as mol- the top of the thighbone (the head of the femur) isluscum contagiosum). not stable within the socket (acetabulum). The liga- ments of the hip joint may also be loose andcondyloma acuminatum A sexually transmitted stretched. The degree of instability at the hip varies.disorder characterized by wartlike growths around The usual treatment is the use of a device called thethe vulva. See also genital warts. Pavlik harness. If the harness is not effective, the hip may be positioned into place under anesthesiacondyloma latum A form of the secondary stage (closed reduction) and maintained with a body castof syphilis, characterized by wartlike growths (spica). Also known as infantile hip dislocation,around the anus. congenital dislocation of the hip (CDH), and devel- opmental dysplasia of the hip (DDH).condyloma subcutaneum A sexually transmit-ted disorder characterized by wartlike growths congenital hypothyroidism See cretinism.around the anus and genitals that is caused by thevirus poxvirus. Also known as molluscum contagio- congenital malformation A physical defectsum. present in a baby at birth that can involve many dif- ferent parts of the body, including the brain, heart,cone biopsy See conization. lungs, liver, bones, and intestinal tract. Congenital malformation can be genetic, it can result from exposure of the fetus to a malforming agent (such
congenital neutropenia, severe 96as alcohol), or it can be of unknown origin. related to systemic diseases, such as Reiter syn-Congenital malformations are now the leading cause drome. Also known as pinkeye.of infant mortality (death) in the US and many otherdeveloped nations. Examples include heart defects, conjunctivitis, allergic Inflammation of thecleft lip and palate, spina bifida, limb defects, and whites of the eyes (the conjunctivae), with itching,Down syndrome. redness, and tearing, that is caused by an allergic reaction and frequently accompanied by hay fever.congenital neutropenia, severe See severecongenital neutropenia. conjunctivitis arida See xerophthalmia.congenital ptosis of the eyelids Drooping of Conn syndrome Overproduction of the hor-the upper eyelids at birth. The lids may droop only mone aldosterone by a tumor in the outer portionslightly, or they may cover the pupils and restrict or (cortex) of the adrenal gland. The excessive aldos-even block vision. Moderate or severe ptosis calls terone results in low potassium levelsfor treatment to permit normal vision development. (hypokalemia), underacidity of the body (alkalo-If congenital ptosis of the eyelids is not corrected, sis), muscle weakness, excessive thirst, excessiveamblyopia (lazy eye) may develop, which can lead urination, and high blood pressure. Also known asto permanently poor vision. aldosteronism and hyperaldosteronism.congenital torticollis See torticollis, congenital. connectionism A theory of information process- ing that is based on the neurophysiology of thecongestive heart failure Inability of the heart to brain. The basic tenets of connectionism are thatkeep up with the demands on it, with failure of the signals are processed by elementary units (in thisheart to pump blood with normal efficiency. When case, neurons), processing units are connected inthis occurs, the heart is unable to provide adequate parallel to other processing units, and connectionsblood flow to other organs, such as the brain, liver, between processing units are weighted. The weightsand kidneys. Abbreviated CHF. CHF may be due to may be hard-wired, learned, or both, and they rep-failure of the right or left ventricle, or both. The resent the strengths of connection (either excitatorysymptoms can include shortness of breath (dysp- or inhibitory) between two units.nea), asthma due to the heart (cardiac asthma),pooling of blood (stasis) in the general body (sys- connective tissue A material consisting of pro-temic) circulation or in the liver’s (portal) circula- tein fibers that form a framework that provides ation, swelling (edema), blueness or duskiness support structure for body tissues. See also colla-(cyanosis), and enlargement (hypertrophy) of the gen.heart. The many causes of CHF include coronaryartery disease leading to heart attacks and heart connective tissue disease A disease (autoim-muscle (myocardium) weakness; primary heart mune or otherwise) that attacks the collagen ormuscle weakness from viral infections or toxins, other core components of connective tissue. Lupussuch as prolonged alcohol exposure; heart valve is a connective tissue disease.disease causing heart muscle weakness due to toomuch leaking of blood or causing heart muscle stiff- connective tissue disease, mixed See mixedness from a blocked valve; hyperthyroidism; and connective tissue disease.high blood pressure. Conor and Bruch disease See typhus, Africanconization Surgery to remove a cone-shaped tick.piece of tissue from the cervix and cervical canal.Conization may be used to diagnose or treat a cervi- consanguinity Close blood relationship, some-cal condition. Also known as cone biopsy. times used to denote human inbreeding. Mating of closely related persons can cause significant geneticconjunctiva A thin, clear, moist membrane that disease in offspring. Everyone carries rare recessivecoats the inner surfaces of the eyelids (palpebral genes that, in the company of other genes of theconjunctiva) and the outer surface of the eye (ocu- same type, are capable of causing autosomal reces-lar, or bulbar, conjunctiva). Inflammation of the sive diseases. First cousins share a set of grandpar-conjunctiva is called conjunctivitis (pinkeye). ents, so for any particular gene in one of them, the chance that the other inherited the same allele fromconjunctivitis Inflammation of the membrane the same source is one in eight. For this reason,covering the surface of the eyeball. It can be a result marriage between first cousins (not to mentionof infection or irritation of the eye, or it can be closer relatives) is generally discouraged, and in many areas of the world is illegal. Mating between
97 coprolaliamore distant relatives carries lesser risks. In fami- or circumstance. For example, certain medicationslies where a recessive genetic disorder is known or are contraindicated during pregnancy because ofsuspected to be present, genetic testing and coun- the danger they pose to the fetus, and the use ofseling are advised, even if the level of consanguinity aspirin is contraindicated in small children becauseis very low (as, for example, in marriages between of the danger of Reye’s syndrome.third or fourth cousins). contraindication A condition which makes aconstipation Infrequent and frequently incom- particular treatment or procedure inadvisable.plete bowel movements. Constipation is the oppositeof diarrhea and is commonly caused by irritable contralateral Of or pertaining to the other side.bowel syndrome (IBS), diverticulosis, and medica- The opposite of iposilateral (the same side). Fortions. Paradoxically, constipation can also be example, a stroke involving the right side of the braincaused by overuse of laxatives. Colon cancer can may cause contralateral paralysis of the left leg.also narrow the colon and thereby cause constipa-tion. A high-fiber diet can frequently relieve consti- control In research, the group of participantspation. If the diet is not helpful, medical evaluation that does not receive the treatment under investiga-is warranted. tion. The control group may be given a placebo treatment or receive a treatment with known resultscontinuing medical education See CME. to permit comparison with the results of the exper- iment. In lab research that does not use live partic-continuous positive airway pressure A treat- ipants (in vitro research rather than in vivoment for sleep apnea that involves wearing over the research), control procedures serve the same pur-face a breathing mask that forces air through the pose as a control group.nasal passages at a steady rate, preventing the air-way from collapsing during sleep. Abbreviated CPAP. controlled substance A drug or chemical that isSee also sleep apnea. regulated by the government. This regulation applies to manufacture, possession, and usage.contraceptive Something capable of preventingconception from taking place. See also barrier contusion See bruise.method; birth control; cervical cap; condom;condom, female; condom, male; contraceptive, conventional medicine Medicine as practicedemergency; contraceptive, implanted; Depo- by holders of MD or DO degrees and by their alliedProvera; diaphragm; intrauterine device; oral health professionals, such as physical therapists,contraceptive. psychologists, and registered nurses. Also known as allopathy. See also allopathy.contraceptive, emergency An oral contracep-tive that can be taken after unprotected intercourse. copayment A payment made by an individualFor example, emergency contraceptives may be who has health insurance, usually at the time a serv-given to victims of rape as part of aftercare proce- ice is received, to offset some of the cost of care.dures. Also known as the morning-after pill. Copayments are a common feature of HMO (health maintenance organization) and PPO (preferredcontraceptive, implanted A time-release con- provider organization) health plans in the US.traceptive that is surgically implanted under the Copayment size may vary depending on the service;skin. generally, low copayments are required for visits to a regular medical provider and higher copaymentscontraceptive device, intrauterine See are required for services received in an emergencyintrauterine device. room, the latter intended to discourage insured per- sons from using the emergency room unless it iscontraction The tightening and shortening of a absolutely necessary. Also known as coinsurance.muscle. COPD Chronic obstructive pulmonary disease.contraction, uterine The tightening and short- See chronic obstructive lung disease.ening of the uterine muscles. During labor, contrac-tions cause the cervix to thin and dilate, and they aid coprolalia The involuntary uttering of obscene,the baby in its entry into the birth canal and then its derogatory, or embarrassing words or phrases.progress through the birth canal. Coprolalia is a symptom of Tourette’s syndrome, a tic disorder. Like other tics, coprolalia tends to appearcontraindicate To make a treatment or proce- and disappear, and it responds to medication. Seedure inadvisable because of a particular condition also tic; tic disorder; Tourette’s syndrome.
cord, vocal 98cord, vocal See vocal cord. coronary artery bypass graft See bypass, coronary.corn A small callused area of skin caused by localpressure that irritates tissue over a bony promi- coronary artery disease Impedance or block-nence. Although the surface area of a corn may be age of one or more arteries that supply blood to thesmall, the area of hardening actually extends into heart, usually due to atherosclerosis (hardening ofthe deeper layers of skin and flesh. The inside pro- the arteries). Abbreviated CAD. A major cause of ill-jection of the corn is what causes discomfort. Corns ness and death, CAD begins when hard cholesterolmost commonly occur over a toe, where they form substances (plaques) are deposited within a coro-what is referred to as hard corns. Between the toes, nary artery. The plaques in the coronary arteries canpressure can form a soft corn of macerated skin, lead to the formation of tiny clots that can obstructwhich often yellows. Corns can be softened by soak- the flow of blood to the heart muscle, producinging them in hot water, with or without softening symptoms and signs of CAD, including chest painagents that are available over the counter or by pre- (angina pectoris), heart attack (myocardial infarc-scription. In some cases, minor outpatient surgery tion), and sudden death. Treatment for CADmay be used to remove excess corn tissue. A corn includes bypass surgery, balloon angioplasty, andon the toe is also called a clavus. the use of stents.cornea The clear front window of the eye, which coronary artery spasm A sudden constrictiontransmits and focuses light into the eye. The cornea of a coronary artery that deprives the heart muscleis more than a protective film; it is a fairly complex of blood and oxygen. This can cause a type of sud-structure that has five layers. den chest pain referred to as variant angina or Prinzmetal angina. Coronary artery spasm can becornea, conical See keratoconus. triggered by emotional stress, medicines, street drugs (particularly cocaine), and exposure tocorneal abrasion A scratch or scrape on the extreme cold. Treatments include the use of beta-cornea, the clear front window of the eye that trans- blocker medications and, classically, nitroglycerinmits and focuses light into the eye. Corneal abrasion to allow the coronary arteries to open.can also be caused by excessive dryness to the eye.The cornea can become infected and painful as a coronary occlusion Blockage of a coronaryresult of the abrasion. See also cornea. artery, which can cause a heart attack. See also acute myocardial infarction.corneal dystrophy A condition in which one ormore parts of the cornea lose their normal clarity coronavirus One of a group of viruses, so nameddue to a buildup of cloudy material. There are over because they look like a corona or halo when20 corneal dystrophies that affect all parts of the viewed under the electron microscope.cornea. Coronaviruses are the second leading cause of the common cold (after the rhinoviruses). A new coro-corneal dystrophy, Cogan See Cogan corneal navirus was discovered to be responsible for severedystrophy. acute respiratory syndrome (SARS). See also severe acute respiratory syndrome.corneal ring, intrastromal A plastic ringdesigned to be implanted in the cornea in order to corpora cavernosa Two chambers that run theflatten the cornea and thereby correct, or reduce length of the penis and are filled with spongy tissue.the degree of, nearsightedness (myopia). The ring Blood flows in and fills the open spaces in thisis placed in the corneal stroma, the middle of the spongy tissue to create an erection.five layers of the cornea. corporeal Pertaining to the body of an organ orcoronal plane A vertical two-dimensional imagi- the entire body.nary slice through the body from head to foot andparallel to the shoulders. corpse A dead body. The term corpse is more often used in mystery stories than in medicine,coronary artery A vessel that supplies the heart which prefers the term cadaver.muscle (myocardium) with blood that is rich inoxygen. The coronary arteries encircle the heart in corpus The body of the uterus.the manner of a crown (in Latin, corona means“crown”). Like other arteries, the coronary arteries Corrigan pulse A pulse that is forceful and thenmay be subject to arteriosclerosis (hardening of the suddenly collapses. It is usually found in patientsarteries). See also artery. with aortic regurgitation, a condition caused by a
99 cox-1leaky aortic valve. The left ventricle of the heart costochondritis Inflammation and swelling ofejects blood under high pressure into the aorta. the cartilage of the chest wall, usually involving theThen the aortic valve normally shuts tight so that cartilage that surrounds the breastbone (sternum)blood cannot return to the ventricle. If, however, the but sometimes including the adjacent tip of a rib.aortic valve cannot close completely, the blood in Costochondritis causes local pain and tenderness ofthe aorta comes sloshing back into the ventricle, the chest around the sternum. Treatment optionsand the pressure and the pulse collapse. Also include anti-inflammatory medications and, inknown as water-hammer pulse. severe cases, corticosteroid injections. Also known as Tietze syndrome.cortex The outer layer of any organ. cough A rapid expulsion of air from the lungs,cortex, cerebral The gray outer portion of the typically in order to clear the lung airways of fluids,largest part of the brain, the cerebrum. Because it mucus, or other material. Also known as tussis.has thousands of complex folds, the cerebral cortexhas a much larger surface area than one might cough suppressant A drug used to controlthink. Specific areas of the cerebral cortex govern coughing, particularly with a dry, nagging, unpro-sensory perception, voluntary response to stimuli, ductive cough.thought, memory, and the unique human capabilityof consciousness. The white matter of the brain lies coughing syncope See syncope, coughing.within the cerebral cortex, and it carries instruc-tions arising within the cortex to all other parts of Coumadin See warfarin.the brain and body through an intricate network ofnerve fibers. counseling The therapeutic practice of using dis- cussion to help patients understand and better copecortical Having to do with the cortex, the outer with life’s problems or health issues. Areas in whichlayer of an organ. counseling may be used in medicine include nutri- tion, genetic counseling, and family counselingcortical desmoid tumor See desmoids tumor, (particularly to help the family cope with a mem-cortical. ber’s illness or death). Counselors may also see individuals or married couples, or they may workcorticosteroid Any of the steroid hormones with students in a school setting.made by the outer portion (cortex) of the adrenalgland. There are two sets of these hormones: the counseling, genetic See genetic counseling.glucocorticoids, which are produced in reaction tostress and also help in the metabolism of fats, car- counselor A person who practices counseling.bohydrates, and proteins; and the mineralocorti- Depending on state laws, counselors may or maycoids, which regulate the balance of salt and water not be required to hold particular licenses.within the body. Credentials used by counselors include MFC (mar- riage and family counselor) and LMFC (licensedcortisol A metabolite of the primary stress hor- marriage and family counselor). Genetic counselorsmone cortisone. Cortisol is an essential factor in the are certified by the American Board of Medicialproper metabolism of starches, and it is the major Genetics and the American Board of Geneticnatural glucocorticoid (GC) in humans. Counseling.cortisone A naturally occurring adrenocorticoid cousin marriage See consanguinity.hormone that is produced in minute amounts by theadrenal gland. Synthetic cortisone is also available; Cowper’s gland See bulbourethral gland.it is metabolized by the body into cortisol. Uses forsynthetic oral, intramuscular, and intravenous corti- cowpox A mild skin disease of milk cows, princi-sone medications include treatment of adrenocorti- pally confined to the udder and teats, that can becal deficiency and treatment of conditions contracted by people from milking an infected cow.associated with inflammation. A popular topical Affected people develop vesicles (blebs), whichform is known as hydrocortisone cream. break and form ulcers on the fingers (sometimes called “milkers’ nodules”). These usually heal with-coryza A head cold that includes a runny nose. out scarring.cosmetic surgeon See plastic surgeon. cox-1 Cyclooxygenase-1, an enzyme that acts to speed up the production of certain chemical mes-costal margin The lower edge of the chest (tho- sengers, called prostaglandins, in a variety of areasrax), formed by the bottom edge of the rib cage. of the body such as the stomach, kidneys, and sites
cox-2 100of inflammation. In the stomach, prostaglandins cradle cap A form of seborrheic dermatitis of thepromote the production of a protective natural scalp that is usually seen in infants but sometimesmucus lining. They also interact within certain cells found in older children. It is characterized by flak-that are responsible for inflammation and other ing or scaling of the skin, which may also be red-functions. dened.cox-2 Cyclooxygenase-2, an enzyme that acts to cramp, writer’s A dystonia that affects the mus-speed up the production of certain chemical mes- cles of the hand and sometimes the forearm andsengers, called prostaglandins that play a key role in that only occurs during handwriting. Similar focalin promoting inflammation. When cox-2 activity is dystonias have been called typist’s cramp, pianist’sblocked, inflammation is reduced. Unlike cox-1, cramp, musician’s cramp, and golfer’s cramp.cox-2 is active only at the site of inflammation, notin the stomach. cranial Toward (the opposite of caudad) or of the head. See also Appendix B, “Anatomiccox-2 inhibitor An antiinflammatory drug that Orientation Terms.”selectively blocks the cox-2 enzyme. Blocking thisenzyme impedes the production of the chemical cranial arteritis See arteritis, cranial.messengers that cause the pain and swelling ofarthritis inflammation. Cox-2 inhibitors do not pose cranial dystonia See dystonia, cranial.as great a risk of injuring the stomach or intestinesas drugs that block cox-1. An example of a cox-2 cranial nerves The nerves of the brain, whichinhibitor is celecoxib (brand name: Celebrex). emerge from or enter the skull (the cranium), as opposed to the spinal nerves, which emerge fromCoxsackievirus