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Medical dictionary

  1. 1. TMMedical Dictionary Third Edition From the Doctors and Experts at WebMD
  2. 2. Webster’s New World™ Medical Dictionary, Third EditionCopyright © 2008 All rights reserved.Published by Wiley Publishing, Inc., Hoboken, New JerseyNo part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or byany means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permittedunder Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior writtenpermission of the Publisher, or authorization through payment of the appropriate per-copy fee to theCopyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978)646-8600, or on the web at Requests to the Publisher for permission should beaddressed to the Legal Department, Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256,(317) 572-3447, fax (317) 572-4355, or online at publisher and the author make no representations or warranties with respect to the accuracy orcompleteness of the contents of this work and specifically disclaim all warranties, including withoutlimitation warranties of fitness for a particular purpose. No warranty may be created or extended by sales orpromotional materials. The advice and strategies contained herein may not be suitable for every situation.This work is sold with the understanding that the publisher is not engaged in rendering legal, accounting, orother professional services. If professional assistance is required, the services of a competent professionalperson should be sought. Neither the publisher nor the author shall be liable for damages arising herefrom. The fact that an organization or Website is referred to in this work as a citation and/or a potentialsource of further information does not mean that the author or the publisher endorses the information theorganization or Website may provide or recommendations it may make. Further, readers should be awarethat Internet Websites listed in this work may have changed or disappeared between when this work waswritten and when it is read.Trademarks: Wiley, the Wiley Publishing logo, Webster’s New World, and all related trademarks, logos andtrade dress are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates. Allother trademarks are the property of their respective owners. Wiley Publishing, Inc. is not associated withany product or vendor mentioned in this book.For general information on our other products and services or to obtain technical support, please contactour Customer Care Department within the U.S. at 800-762-2974, outside the U.S. at 317-572-3993, or fax317-572-4002.Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may notbe available in electronic books. For more information about Wiley products, please visit our web site of Congress Cataloging-in-Publication Data is available from the publisher upon request.ISBN: 978-0-470-18928-3Printed in the United States of America10 9 8 7 6 5 4 3 2 1Book production by Wiley Publishing, Inc. Composition Services
  3. 3. TMMedical Dictionary Third Edition From the Doctors and Experts at WebMD
  4. 4. Webster’s New World™ Medical Dictionary, Third EditionCopyright © 2008 All rights reserved.Published by Wiley Publishing, Inc., Hoboken, New JerseyNo part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or byany means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permittedunder Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior writtenpermission of the Publisher, or authorization through payment of the appropriate per-copy fee to theCopyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978)646-8600, or on the web at Requests to the Publisher for permission should beaddressed to the Legal Department, Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256,(317) 572-3447, fax (317) 572-4355, or online at publisher and the author make no representations or warranties with respect to the accuracy orcompleteness of the contents of this work and specifically disclaim all warranties, including withoutlimitation warranties of fitness for a particular purpose. No warranty may be created or extended by sales orpromotional materials. The advice and strategies contained herein may not be suitable for every situation.This work is sold with the understanding that the publisher is not engaged in rendering legal, accounting, orother professional services. If professional assistance is required, the services of a competent professionalperson should be sought. Neither the publisher nor the author shall be liable for damages arising herefrom. The fact that an organization or Website is referred to in this work as a citation and/or a potentialsource of further information does not mean that the author or the publisher endorses the information theorganization or Website may provide or recommendations it may make. Further, readers should be awarethat Internet Websites listed in this work may have changed or disappeared between when this work waswritten and when it is read.Trademarks: Wiley, the Wiley Publishing logo, Webster’s New World, and all related trademarks, logos andtrade dress are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates. Allother trademarks are the property of their respective owners. Wiley Publishing, Inc. is not associated withany product or vendor mentioned in this book.For general information on our other products and services or to obtain technical support, please contactour Customer Care Department within the U.S. at 800-762-2974, outside the U.S. at 317-572-3993, or fax317-572-4002.Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may notbe available in electronic books. For more information about Wiley products, please visit our web site of Congress Cataloging-in-Publication Data is available from the publisher upon request.ISBN: 978-0-470-18928-3Printed in the United States of America10 9 8 7 6 5 4 3 2 1Book production by Wiley Publishing, Inc. Composition Services
  5. 5. AcknowledgmentsAt, 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 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, particularly Gene Lu and David Sorenson, who havesupported the development of this dictionary.The excellence of the technical and editorial staffs at 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, 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
  6. 6. 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’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 Content ManagersMelissa Conrad Stöppler, MD Cynde Kelly McKiernan www.MedicineNet.comAssistant EditorsDennis Lee, MD Concept David Sorenson Gene LuJay W. Marks, MD
  7. 7. 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 since its found-ing in 1996. He was co-editor-in-chief of the first and second editions of Webster’s New WorldMedical Dictionary.
  8. 8. 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, and is the ChiefMedical Editor of, 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
  9. 9. 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 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 •
  10. 10. 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
  11. 11. 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, part of the WebMD Health Network. One of the earliesthealth information sites on the Internet, 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, 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 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 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 ensures anunusual degree of professional expertise, reliability, and perspective.
  12. 12. As a bonus, this edition includes a companion Web site at 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.
  13. 13. 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
  14. 14. 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.
  15. 15. 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.
  16. 16. 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.
  17. 17. 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.
  18. 18. 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.
  19. 19. 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 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
  20. 20. 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.
  21. 21. 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 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.
  22. 22. 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 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.
  23. 23. 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 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 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
  24. 24. 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.
  25. 25. 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.