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Saladin anatomy and physiology unity of form and function 6th c2012 txtbk Saladin anatomy and physiology unity of form and function 6th c2012 txtbk Document Transcript

  • Sixth Edition & The Unity of Form and Function Kenneth S. Saladin Georgia College & State University TM sal78259_fm_i-xxvi.indd i 11/19/10 9:31 AM
  • TM ANATOMY & PHYSIOLOGY: THE UNITY OF FORM AND FUNCTION, SIXTH EDITION Published by McGraw-Hill, a business unit of The McGraw-Hill Companies, Inc., 1221 Avenue of the Americas, New York, NY 10020. Copyright © 2012 by The McGraw-Hill Companies, Inc. All rights reserved. Previous editions © 2010, 2007, and 2004. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written consent of The McGraw-Hill Companies, Inc., including, but not limited to, in any network or other electronic storage or transmission, or broadcast for distance learning. Some ancillaries, including electronic and print components, may not be available to customers outside the United States. This book is printed on acid-free paper. 1 2 3 4 5 6 7 8 9 0 QVR/QVR 1 0 9 8 7 6 5 4 3 2 1 ISBN 978–0–07–337825–1 MHID 0–07–337825–9 Vice President, Editor-in-Chief: Marty Lange Vice President, EDP: Kimberly Meriwether David Senior Director of Development: Kristine Tibbetts Executive Editor: James F. Connely Developmental Editor: Ashley Zellmer Marketing Manager: Denise M. Massar Senior Project Manager: Vicki Krug Senior Buyer: Sandy Ludovissy Lead Media Project Manager: Stacy A. Vath Senior Designer: David W. Hash Cover Designer: John Joran Cover Art Overlay: Imagineering Cover Image: ©Mike Powell/Stone/Getty Images Senior Photo Research Coordinator: John C. Leland Photo Research: Mary Reeg Compositor: Electronic Publishing Services Inc., NYC Typeface: 10/12 Melior Printer: Quad/Graphics All credits appearing on page or at the end of the book are considered to be an extension of the copyright page. Library of Congress Cataloging-in-Publication Data Saladin, Kenneth S. Anatomy & physiology : the unity of form and function / Kenneth S. Saladin. -- 6th ed. p. cm. Includes index. ISBN 978–0–07–337825–1 — ISBN 0–07–337825–9 (hard copy: alk. paper) 1. Human physiology. 2. Human anatomy. I. Title. II. Title: Anatomy and physiology. QP34.5.S23 2012 612--dc22 2010042586 sal78259_fm_i-xxvi.indd ii 11/19/10 11:47 AM
  • BRIEF About the Author iv Preface v Reviewers xxi Contents xxii Letter to the Students xxvi 16 17 Contents Sense Organs 582 The Endocrine System 633 PART FOUR Regulation and Maintenance PART ONE Organization of the Body 1 2 3 4 5 Major Themes of Anatomy and Physiology 1 Atlas A General Orientation to Human Anatomy 28 The Chemistry of Life 42 Cellular Form and Function 78 Genetics and Cellular Function 114 Histology 143 18 19 20 21 22 23 24 25 26 The Circulatory System: Blood 678 The Circulatory System: The Heart 714 The Circulatory System: Blood Vessels and Circulation 749 The Lymphatic and Immune Systems 808 The Respiratory System 854 The Urinary System 895 Water, Electrolyte, and Acid–Base Balance 930 The Digestive System 953 Nutrition and Metabolism 1000 PART TWO Support and Movement 6 7 8 9 10 11 The Integumentary System 180 Bone Tissue 206 The Skeletal System 233 Joints 278 The Muscular System 312 Atlas B Regional and Surface Anatomy 379 Muscular Tissue 401 PART THREE Integration and Control 12 13 14 15 sal78259_fm_i-xxvi.indd iii Nervous Tissue 439 The Spinal Cord, Spinal Nerves, and Somatic Reflexes 478 The Brain and Cranial Nerves 511 The Autonomic Nervous System and Visceral Reflexes 561 PART FIVE Reproduction and Development 27 28 29 The Male Reproductive System 1034 The Female Reproductive System 1064 Human Development and Aging 1102 Appendix A. Periodic Table A-1 Appendix B. Answer Keys A-2 Appendix C. Symbols of Weight and Measures A-13 Appendix D. Biomedical Abbreviations A-14 Glossary G-1 Credits C-1 Index I-1 11/19/10 9:53 AM View slide
  • ABOUT THE Author KENNETH S. SALADIN has taught since 1977 at Georgia College and State University in Milledgeville, Georgia. He earned a B.S. in zoology at Michigan State University and a Ph.D. in parasitology at Florida State University, with interests especially in the sensory ecology of freshwater invertebrates. In addition to human anatomy and physiology, his teaching experience includes histology, parasitology, animal behavior, sociobiology, introductory biology, general zoology, biological etymology, and study abroad in the Galápagos Islands. Ken has been recognized as “most significant undergraduate mentor” nine times over the years by outstanding students inducted into Phi Kappa Phi. He received the university’s Excellence in Research and Publication Award for the first edition of this book, and was named Distinguished Professor in 2001. Ken is a member of the Human Anatomy and Physiology Society, the Society for Integrative and Comparative Biology, the American Association of Anatomists, and the American Association for the Advancement of Science. He served as a developmental reviewer and wrote supplements for several other McGraw-Hill anatomy and physiology textbooks for a number of years before becoming a textbook writer. Ken’s outside interests include the Big Brothers/ Big Sisters program for single-parent children, the Charles Darwin Research Station in the Galápagos, and student scholarships. Ken is married to Diane Saladin, a registered nurse. They have two adult children. This book is dedicated to the memory of H. Kenneth Hamill and with gratitude to Big Brothers–Big Sisters of Greater Kalamazoo Big Brothers–Big Sisters of America iv sal78259_fm_i-xxvi.indd iv 12/2/10 9:18 AM View slide
  • THE EVOLUTION OF A Storyteller Ken Saladin’s first step into authoring was a 318-page paper on the ecology of hydras written for his 10th-grade biology class. With his “first book,” featuring 53 original India ink drawings and photomicrographs, a true storyteller was born. “When I first became a textbook writer, I found myself bringing the same enjoyment of writing and illustrating to this book that I first discovered back when I was 15.” –Ken Saladin Ken's “first book,” Hydra Ecology, 1965 One of Ken’s drawings from Hydra Ecology Ken in 1964 Ken began working on his first book for McGraw-Hill in 1993, and in 1997 the first edition of The Unity of Form and Function was published. In 2011 the story continues with the sixth edition of Ken’s best-selling A&P textbook. The first edition (1997) The story continues (2011) v sal78259_fm_i-xxvi.indd v 11/19/10 9:31 AM
  • SALADIN ANATOMY & PHYSIOLOGY A Good Story Anatomy & Physiology: The Unity of Form and Function tells a story made of many layers including the core science, clinical applications, the history of medicine, and the evolution of the human body. Saladin combines this humanistic perspective on anatomy and physiology with vibrant photos and art to convey the beauty and excitement of the subject to beginning students. To help students manage the tremendous amount of information in this introductory course, the narrative is broken into short segments, each framed by expected learning outcomes and self-testing review questions. This presentation strategy works as a whole to create a more efficient and effective way for students to learn A&P. “Ken Saladin’s Anatomy & Physiology: The Unity of Form and Function, 6th edition, provides a fresh approach to the study of A&P, with modern pedagogy, an abundance of ancillary learning resources, and the most up-to-date information. Instructors and students alike will benefit from the Saladin experience.” Storytelling Writing Style viii–x Appropriate Level Interactive Material Interesting Reading Artwork That Encourages Learning xi–xii Sets the Standard Conducive to Learning Pedagogical Learning Tools xiii–xiv Engaging Chapter Layouts Tiered Assessments Based on Key Lists of Expected Learning Outcomes Innovative Chapter Sequencing xv The Saladin Digital Story xvi-xix –David Manry, Hillsborough Community College What’s New in the Sixth Edition? New Atlas Organization Many figures of regional anatomy (former figs. A.12–A.22) are moved from atlas A to atlas B, now titled “Regional and Surface Anatomy.” Beside shortening atlas A and moving the student more quickly to chapter 2, this moves some anatomical detail to a later point where students will be better equipped to understand it and relate it to surface anatomy. New Deeper Insight Essays New essays introduce contemporary issues in health science and a fascinating historical account that underscores some principles of respiratory physiology. It’s not unusual to hear textbook cynics say that new editions are just the same material bound in new covers, but that certainly isn’t true of this one. Just listing my sixth-edition changes came to 50 pages and 18,000 words. —Ken Saladin • Trans fats and cardiovascular disease (Deeper Insight 2.3) • Bone marrow and cord blood transplants (Deeper Insight 18.3) • Altitude sickness and the Zenith ballooning tragedy (Deeper Insight 22.3) vi sal78259_fm_i-xxvi.indd vi 12/2/10 9:18 AM
  • New Science New Art Saladin’s Anatomy & Physiology, sixth edition, stays abreast of key developments in science. Yet, more efficient writing and illustration result in a book slightly shorter than the fifth edition even with these additions. • Cis- and trans-fatty acids (fig. 2.20) • Advances in tissue engineering (chapter 5) • The stem-cell controversy and induced pluripotent stem cells (chapter 5) • Melanoma (chapter 6) • Cola beverages and bone loss (chapter 7) • Bases of muscle fatigue (chapter 11) • Microglia and astrocyte functions (chapter 12) • Neural mechanism of working memory (chapter 12) • Hypothalamic control of hunger and satiety (chapter 14) • Orexins, sleep, and narcolepsy (chapter 14) • Vascular pathogenesis in diabetes mellitus (chapter 17) • Glycemic index of foods (chapter 26) • Treatment of alcoholism (chapter 26) • Vaccination against human papillomavirus (chapter 27) • In vitro fertilization and the 2010 Nobel Prize (chapter 29) New Writing Several sections have been rewritten for improved clarity, especially: • Carrier-mediated membrane transport (chapter 3) • Genetic translation and ribosomal function (chapter 4) • A better example of an anatomical second-class lever (chapter 9) • Muscle compartments and blood supply (chapter 10) • Smooth muscle physiology (chapter 11) • A view of saltatory conduction more accurate than most textbook presentations (chapter 12) • The adrenal cortex (chapter 17) • Causes of arteriosclerosis and distinctions between arteriosclerosis and atherosclerosis (chapter 20) New Photographs • Genetic translation (fig. 4.8) • Types of cell junctions (fig. 5.28) • Embryonic development of exocrine and endocrine glands (fig. 5.29) • Serous membrane histology (fig. 5.33b) • The femur as a second-class lever (fig. 9.9b) • The spinal reflex arc (fig. 13.21) • Oxyhemoglobin dissociation curves (figs. 22.24 and 22.27) • Connective Issues art and layouts New Pedagogy • Brushing Up is fleshed out and repositioned to better catch the student’s attention and emphasize the importance of understanding earlier material before starting a new chapter. • A list of Expected Learning Outcomes heads up each chapter subdivision and exercises called Assess Your Learning Outcomes end each chapter as a whole. Instructors can now easily show how their courses are outcome-driven. • Apply What You Know questions, formerly called Think About It, stress that these thought exercises are analytical applications of basic anatomy and physiology knowledge to clinical situations and other new contexts. Students can see how the basic anatomy and physiology they are learning will be relevant to analyzing new problems. • Building Your Medical Vocabulary, new to each endof-chapter Study Guide, focuses on familiarity with the most common and useful biomedical word roots and affixes. Like a mini-medical vocabulary course, this will help students with retention, spelling, and insight into medical terms, and ability to more comfortably approach even new terms beyond the scope of this book. • Muscle tables in chapter 10 are organized in a new, more columnar format and enhanced with new color shading for easier reading and learning. • Male-female pelvic differences (fig. 8.37) • Treatment of infant hip dislocation (fig. 9.27) • External anatomy of the orbital region (fig. 16.22) • Use of a spirometer (fig. 22.17) vii sal78259_fm_i-xxvi.indd vii 11/19/10 9:31 AM
  • STORYTELLING Writing Style Appropriate Level • Plain language for A&P students early in their curricula • Careful word selection and paragraph structure • Appropriate for all audiences (international readers, English as a second language, and nontraditional students) “The physiological mechanisms presented throughout the text emphasize the basic fundamental processes that occur in the human body. I believe the information is simplistic enough for students to comprehend yet detailed to provide important information […] for students and for instructors to present during lectures.” • Avoidance of "dumbed down" content Interactive Material • Review activities integrated in the chapter • Self-teaching prompts and simple experiments liberally seeded through the narrative —Scott Pallotta, Baker College at Allen Park • Learning aids such as pronunciation guides and insights into the origins and root meanings of medical terms The Temporal Bones If you palpate your skull just above and anterior to the ear—that is, the temporal region—you can feel the temporal bone, which forms the lower wall and part of the floor of the cranial cavity (fig. 8.10). The temporal bone derives its name from the fact that people often develop their first gray hairs on the temples with the passage of time.9 The relatively complex shape of the temporal bone is best understood by dividing it into four parts: Z Homeostasis and Negative Feedback e ● Self-teaching prompts make reading more active. Word origins are footnoted. Pro-NUN-see-AY-shun guides help beginning students master A&P. Familiarity with word origins helps students retain meaning and spelling. The human body has a remarkable capacity for selfrestoration. Hippocrates commented that it usually returns to a state of equilibrium by itself, and people recover from most illnesses even without the help of a physician. This tendency results from homeostasis18 (HO-me-oh-STAY-sis), the body’s ability to detect change, activate mechanisms that oppose it, and thereby maintain relatively stable internal conditions. French physiologist Claude Bernard (1813–78) observed that the internal conditions of the body remain quite constant even when external conditions vary greatly. For example, whether it is freezing cold or swelteringly hot outdoors, the internal temperature of the body stays within a range of about 36° to 37°C (97°–99°F). American physiologist Walter Cannon (1871–1945) coined the term homeostasis for this tendency to maintain internal stability. Homeostasis has been one of the most enlightening theories in physiology. We now see physiology as largely a group of mechanisms for maintaining homeostasis, and the loss of homeostatic control as the cause of illness and death. Pathophysiology is essentially the study of 18 homeo = the same; stas = to place, stand, stay viii sal78259_fm_i-xxvi.indd viii 12/2/10 10:55 AM
  • STORYTELLING Writing Style Interesting Reading • Students say the enlightening analogies, clinical applications, historical notes, biographical vignettes, and evolutionary insights make the book not merely informative, but a pleasure to read. 458 Integration and Control Axon Cell body Signal Action potential in progress ++++–––+++++++++++ ––––+++––––––––––– Refractory membrane Excitable membrane ––––+++––––––––––– ++++–––+++++++++++ +++++++++–––++++++ –––––––––+++–––––– –––––––––+++–––––– +++++++++–––++++++ • Even instructors say they often learn something new and interesting from Saladin’s innovative perspectives. +++++++++++++–––++ –––––––––––––+++–– –––––––––––––+++–– +++++++++++++–––++ FIGURE 12.16 Conduction of a Nerve Signal in an Unmyelinated Fiber. Note that the membrane polarity is reversed in the region of the action potential (red). A region of membrane in its refractory period (yellow) trails the action potential and prevents the nerve signal from going backward toward the soma. The other membrane areas (green) are fully polarized and ready to respond. voltage-gated channels immediately distal to the action potential. Sodium and potassium channels open and close just as they did at the trigger zone, and a new action potential is produced. By repetition, this excites the membrane immediately distal to that. This chain reaction continues until the traveling signal reaches the end of the axon. Note that an action potential itself does not travel along an axon; rather, it stimulates the production of a new action potential in the membrane just ahead of it. Thus, we can distinguish an action potential from a nerve signal. The nerve signal is a traveling wave of excitation produced by self-propagating action potentials. It is like a line of falling dominoes. No one domino travels to the end of the line, but each domino pushes over the next one and there is a transmission of energy from the first domino to the last. Similarly, no one action potential travels to the end of an axon; a nerve signal is a chain reaction of action potentials. If one action potential stimulates the produ production of a new one next to it, you might think that the si signal could also start traveling backward and return to the s soma. This does not 9 Joints membrane CHAPTER occur, however, because the membra behind 305 the nerve signal is still in its refractory period a and cannot be restimulated. Only the membrane ahead is s sensitive to Clinical applications make the abstract science more relevant. DEEPER INSIGHT 9.4 PART THREE Dendrites Clinical Application Knee Injuries and Arthroscopic Surgery Although the knee can bear a lot of weight, it is highly vulnerable to rotational and horizontal stress, especially when the knee is flexed (as in skiing or running) and receives a blow from behind or from the side. The most common injuries are to a meniscus or the anterior cruciate ligament (ACL) (fig. 9.30). Knee injuries heal slowly because ligaments and tendons have a scanty blood supply and cartilage usually has no blood vessels at all. The diagnosis and surgical treatment of knee injuries have been greatly improved by arthroscopy, a procedure in which the interior of a joint is viewed with a pencil-thin instrument, the arthroscope, inserted through a small incision. The arthroscope has a light, a lens, and fiber optics that allow a viewer to see into the cavity and take photographs or video recordings. A surgeon can also withdraw samples of synovial fluid by arthroscopy or inject saline into the joint cavity to expand it and provide a clearer view. If surgery is required, additional small incisions can be made for the surgical instruments and the procedures can be observed through the arthroscope or on a monitor. Arthroscopic surgery produces much less tissue damage than conventional surgery and enables patients to recover more quickly. Orthopedic surgeons now often replace a damaged ACL with a graft from the patellar ligament or a hamstring tendon. The surgeon “harvests” a strip from the middle of the patient’s ligament (or tendon), drills a hole into the femur and tibia within the joint cavity, threads the ligament through the holes, and fastens it with biodegradable screws. The grafted ligament is more taut and “competent” than the damaged ACL. It becomes ingrown with blood vessels and serves as a substrate for the deposition of more collagen, which further strengthens it in time. Following arthroscopic ACL reconstruction, a patient typically must use crutches for 7 to 10 days and undergo supervised physical therapy for 6 to 10 weeks, followed by self-directed exercise therapy. Healing is completed in about 9 months. Analogies explain tough scientific content in a way students can understand. voltage-gated channels immediately distal to the action potential. Sodium and potassium channels open and close just as they did at the trigger zone, and a new action potential is produced. By repetition, this excites the membrane immediately distal to that. This chain reaction continues Myelinated Fibers until the traveling signal reaches the end of the axon. e Matters are somewhat different in myelinated fibers. e Voltage-gated ion channels are scarce in the myelinte e Note that an action potential itself does not travel te covered internodes—fewer than 25/μm in these regions compared with 2,000 to 12,000/μm at the nodesrather, it stimulates the production of a new w along an axon; of h Ranvier. There would be little point in having ion chane nels in the internodes—myelin insulates the fiber from action potential the ECF at these points, and Na from the ECF could not in the membrane just ahead of it. Thus, t h flow into th cell even if more channels were present. the Therefore, n action we can distinguish an action potential from a nerve signal. no potentials can occur in the interd nodes, and the nerve signal requires some other way of h traversing th distance from one node to thesignal is a traveling wave of excitation produced the The nerve next. When N enters the axon at a node of Ranvier, it Na r diffuses for a short distanceself-propagating action potentials. It is like a line of by along the inner face of the ( axolemma (fig. 12.17a). Each sodium ion has an electrio cal field around it. When one Na moves toward another, falling dominoes. No one domino travels to the end of the its field repels the second ion, which moves slightly and p repels another, and so forth—like two magnets that repel th h each other if you try line, but each domino pushes over the next one and there to push their north poles together. i No one ion moves very far, but this energy transfer on n is a faster and farther than any w travels down the axon much transmission of energy from the first domino to the last. of the individual ions. The signal grows weaker with iv ho distance, however, partly because the axoplasm resists ential Similarly, no one action potential travels to the end of an me the movement of the ions and partly because Na leaks back out of the axon along thea nerve signal is a chain reaction of action potentials. o axon; way. Therefore with n th h distance, there is a lower and lower concentration of Na to relay the charge. Furthermore, with a surplus of ay y If one action potential stimulates the production of a timulates ha positive charges on the inner face of the axolemma and o a surplus of negative charges on the outer face, these ht new one other through cations and  anions are attracted to eachnext to it, you might think that the signal could d ra a the membrane—like the opposite poles of two magnets d ea attracting each other also astartcardboard. This through sheet of traveling backward and return to the soma. This does not occur, however, because the membrane behind ecause s the nerve signal is still in its refractory period and cannot be restimulated. Only the membrane ahead is sensitive to embrane 2 2 + + + + + Twisting motion Foot fixed Anterior cruciate ligament (torn) Tibial collateral ligament (torn) Medial meniscus (torn) Patellar ligament FIGURE 9.30 Knee Injuries. The ligaments of the ankle include (1) anterior and posterior tibiofibular ligaments, which bind the tibia to the fibula; (2) a multipart medial (deltoid30) ligament, which binds the tibia to the foot on the medial side; and (3) a multipart lateral (collateral) ligament, which binds the fibula to the foot on the lateral side. The calcaneal (Achilles) tendon extends from the calf muscles to the calcaneus. It plantarflexes the foot and limits dorsiflexion. Plantar flexion is limited by extensor tendons on the anterior side of the ankle and by the anterior part of the joint capsule. Sprains (torn ligaments and tendons) are common at the ankle, especially when the foot is suddenly inverted or everted to excess. They are painful and usually accompanied by immediate swelling. They are best treated by immo- stimulation. The refractory period thus ensures that nerve signals are conducted in the proper direction, from the soma to the synaptic knobs. A traveling nerve signal is an electrical current, but it is not the same as a current traveling through a wire. A current in a wire travels millions of meters per second and is decremental—it gets weaker with distance. A nerve signal is much slower (not more than 2 m/s in unmyelinated fibers), but it is nondecremental. Even in the longest axons, the last action potential generated at a synaptic knob has the same voltage as the first one generated at the trigger oltage la a zone. To clarify this concept, we can compare the nerve signal to a b burning fuse. When a fuse is lit, the heat ignites m powder immediately in front of this point, and this repeats e itself in a self-propagating fashion until the end of the fuse is reached. A the end, the fuse burns just as hotly as it did At n at the beginning. In a fuse, the combustible powder is the o source of po potential energy that keeps the process going in m a nondecremental fashion. In an axon, the potential energy m comes from the ion gradient across the plasma membrane. i Thus, the si signal does not grow weaker with distance; it is a self-propagating, like the burning of a fuse. bilizing the joint and reducing swelling with an ice pack, but in extreme cases may require a cast or surgery. Sprains and other joint disorders are briefly described in table 9.1. “Saladin is a gifted author, and his conversational tone will be sure to keep students very engaged.” —Davonya Person, Auburn University Before You Go On Answer the following questions to test your understanding of the preceding section: 12. What keeps the mandibular condyle from slipping out of its fossa in a posterior direction? 13. Explain how the biceps tendon braces the shoulder joint. 14. Identify the three joints found at the elbow and name the movements in which each joint is involved. 15. What keeps the femur from slipping backward off the tibia? delt = triangular, Greek letter delta (∆); oid = resembling 30 16. What keeps the tibia from slipping sideways off the talus? ix sal78259_fm_i-xxvi.indd ix 11/19/10 9:32 AM
  • CHAPTER 25 DEEPER INSIGHT 25.5 Medical History The Man with a Hole in His Stomach Perhaps the most famous episode in the history of digestive physiology began with a grave accident in 1822 on Mackinac Island in northern Michigan. Alexis St. Martin, a 28-year-old Canadian voyageur (fig. 25.33), was standing outside a trading post when he was accidentally hit by a shotgun blast from 3 feet away. A frontier Army doctor stationed at Fort Mackinac, William Beaumont, was summoned to examine St. Martin. As Beaumont later wrote, “a portion of the lung as large as a turkey’s egg” protruded through St. Martin’s lacerated and burnt flesh. Below that was a portion of the stomach with a puncture in it “large enough to receive my forefinger.” Beaumont did his best to pick out bone fragments and dress the wound, though he did not expect St. Martin to survive. Surprisingly, he lived. Over a period of months the wound extruded pieces of bone, cartilage, gunshot, and gun wadding. As the wound healed, a fistula (hole) remained in the stomach, so large that Beaumont had to cover it with a compress to prevent food from coming out. The opening remained, covered only by a loose flap of skin, for the rest of St. Martin's life. A fold of tissue later grew over the fistula, but it was easily opened. A year later, St. Martin was still feeble. Town authorities decided they could no longer support him on public funds and wanted to ship him 1,500 miles to his home. Beaumont, however, was imbued with a passionate sense of destiny. Very little was known about digestion, and he saw the accident as a unique opportunity to learn. He took St. Martin in at his personal expense and performed 238 experiments on him over several years. Beaumont had never attended medical school and had little idea how scientists work, yet he proved to be an astute experimenter. Under crude frontier conditions and with almost no equipment, he discovered many of the basic facts of gastric physiology discussed in this chapter. “I can look directly into the cavity of the stomach, observe its motion, and almost see the process of digestion,” Beaumont wrote. “I can pour in water with a funnel and put in food with a spoon, and draw them out again with a siphon.” He put pieces of meat on a string into the stomach and removed them hourly for examination. He sent vials of gastric juice to the leading chemists of America and Europe, who could do little but report that it contained hydrochloric acid. He proved that digestion required HCl and could even occur outside the stomach, but he found that HCl alone did not digest meat; gastric juice must contain some other digestive ingredient. Theodor Schwann, one of the founders of the cell theory, identified that ingredient as pepsin. Beaumont also demonstrated that gastric juice is secreted only in response to food; it did not accumulate between meals as previously thought. He disproved the idea that hunger is caused by the walls of the empty stomach rubbing against each other. Now disabled from wilderness travel, St. Martin agreed to participate in Beaumont's experiments in exchange for room and board—though he felt helpless and humiliated by it all. The fur trappers taunted him as “the man with a hole in his stomach,” and he The Digestive System 995 longed to return to his work in the wilderness. He had a wife and daughter in Canada whom he rarely got to see, and he ran away repeatedly to join them. He was once gone for 4 years before poverty made him yield to Beaumont’s financial enticement to come back. Beaumont despised St. Martin's drunkenness and profanity and was quite insensitive to his embarrassment and discomfort over the experiments. Yet St. Martin’s temper enabled Beaumont to make the first direct observations of the relationship between emotion and digestion. When St. Martin was particularly distressed, Beaumont noted little digestion occurring—as we now know, the sympathetic g g y p nervous system inhibits digestive activity. em Beaumont published a book in 1833 that laid the foundation nt for modern gastric physiology and dietetics. It was enthusiastically received by the medical community and had no equal until Russian physiologist Ivan Pavlov (1849–1936) performed his celebrated experivan ments on digestion in animals. Building on the methods pioneered by gestion Beaumont, Pavlov received the 1904 Nobel Prize for Physiology or Medicine. In 1853, Beaumont slipped on some ice, suffered a blow to the suffered f base of his skull, and died a few weeks later. St. Martin continued to tour medical schools and submit to experiments by other physiical ologists, whose conclusions were often less correct than Beaumont’s. ose Some, for example, attributed chemical digestion to lactic acid instead of hydrochloric acid. St. Martin lived in wretched poverty in a drochloric tiny shack with his wife and several children, and died 28 years after th Beaumont. By then he was senile and believed he had been to Paris, y where Beaumont had often promised to take him. mont Medical History Saladin “puts the human in human A&P” with his occasional vignettes on the people behind the science. Students say these stories make learning A&P more fun and stimulating. y p p conditions and with almost no equipment, he discovered many of the basic facts of gastric physiology discussed in this chapter. “I can look directly into the cavity of the stomach, observe its motion, and almost see the process of digestion,” Beaumont wrote. “I can pour in water with a funnel and put in food with a spoon, and draw them out again with a siphon.” He put pieces of meat on a string into the stomach and removed them hourly for examination. He sent vials of gastric juice to the leading chemists of America and Europe, who could do little but report that it contained hydrochloric acid. He proved that digestion required HCl and could even occur outside the stomach, but he found that HCl alone did not digest meat; gastric juice must contain some other digestive ingredient. Theodor Schwann, one of the founders of the cell theory, identified that ingredient as pepsin. Beaumont also demonstrated that gastric juice is secreted only in response to food; it did not accumulate between meals as previously thought. He disproved the idea that hunger is caused by the walls of the empty stomach rubbing against each other. Now disabled from wilderness travel, St. Martin agreed to participate in Beaumont's experiments in exchange for room and board—though he felt helpless and humiliated by it all. The fur trappers taunted him as “the man with a hole in his stomach,” and he umont William Beaumont (1785–1853) William Beaumont (1785–1853) Alexis St. Martin (1794–1880) FIGURE 25.33 Doctor and Patient in a Pioneering Study of Digestion. Alexis St. Martin (1794–1880) FIGURE 25.33 Doctor and Patient in a Pioneering Study of 5.33 33 3 Digestion. More than a few distinguished scientists and clinicians say they found their inspiration in reading of the lives of their predecessors. Maybe these stories will inspire some of our own students to go on to do great things. –Ken Saladin 1076 Evolutionary Medicine Rapidly growing, increasingly fascinating Evolutionary medicine provides novel and intriguing ways of looking at: • menopause • the sweet tooth • bipedalism • the origin of mitochondria • skin color • body hair • lactose intolerance • the kidney and life on dry land • the palate • theories of aging and death DEEPER INSIGHT 28.2 PART FIVE Reproduction and Development stimulates gonadotropin secretion. Therefore, if body fat and leptin levels drop too low, gonadotropin secretion declines and a girl’s or woman’s menstrual cycle may cease. Adolescent girls with very low body fat, such as avid dancers and gymnasts, tend to begin menstruating at a later age than average. Menarche does not necessarily signify fertility. A girl’s first few menstrual cycles are typically anovulatory (no egg is ovulated). Most girls begin ovulating regularly about a year after they begin menstruating. Estradiol stimulates many other changes of puberty. It causes the vaginal metaplasia described earlier. It stimulates growth of the ovaries and secondary sex organs. It stimulates growth hormone secretion and causes a rapid increase in height and widening of the pelvis. Estradiol is largely responsible for the feminine physique because it stimulates fat deposition in the mons pubis, labia majora, hips, thighs, buttocks, and breasts. It makes a girl’s skin thicken, but the skin remains thinner, softer, and warmer than in males of corresponding age. Progesterone27 acts primarily on the uterus, preparing it for possible pregnancy in the second half of each menstrual cycle and playing roles in pregnancy discussed later. Estrogens and progesterone also suppress FSH and LH secretion through negative feedback inhibition of the anterior pituitary. Inhibin selectively suppresses FSH secretion. Thus, we see many hormonal similarities in males and females from puberty onward. The sexes differ less in the identity of the hormones that are present than in their relative amounts—high levels of androgens and low levels of estrogens in males and the opposite in females. Another difference is that these hormones are secreted more or less continually and simultaneously in males, whereas in females, secretion is distinctly cyclic and the hormones are secreted in sequence. This will be very apparent as you read about the ovarian and menstrual cycles. Evolutionary Medicine The Evolution of Menopause There has been considerable speculation about why women do not remain fertile to the end of their lives, as men do. Some theorists argue that menopause served a biological purpose for our prehistoric foremothers. Human offspring take a long time to rear. Beyond a certain point, the frailties of age make it unlikely that a woman could rear another infant to maturity or even survive the stress of pregnancy. She might do better in the long run to become infertile and finish rearing her last child, or help to rear her grandchildren, instead of having more. In this view, menopause was biologically advantageous for our Climacteric and Menopause ancestors—in other words, an evolutionary adaptation. Women, like men, go through a midlife change in hormone secretion called the climacteric. In women, it is Others argue against this hypothesis on the grounds thatthe cessation of menstruaaccompanied by menopause, Pleistocene tion (see Deeper Insight 28.2). A female born with about 2 past age (Ice Age) skeletons indicate that early hominids israrely livedmillion eggs in her ovaries, each in its own follicle. The older she gets, the fewer follicles 45 Climacteric begins not of specific 40. If this is true, menopause setting in at 55  years at anyage age, but when she has only about 1,000 follicles left. Even the remaining follicles are less responsive women could have served little purpose. In this view, Pleistocene to gonadotropins, so they secrete less estrogen and progesterone. Without these steroids, their lives; breasts atrophy. Intercourse may indeed have been fertile to the end of the uterus, vagina, andmenopause more may become uncomfortable, and vaginal infections now may be just an artifact of modern nutrition and medicine, which have made it possible for us to live much longer than our ancestors did. 27 common, as the vagina becomes thinner, less distensible, and drier. The skin becomes thinner, cholesterol levels rise (increasing the risk of cardiovascular disease), and bone mass declines (increasing the risk of osteoporosis). Blood vessels constrict and dilate in response to shifting hormone balances, and the sudden dilation of cutaneous arteries may cause hot flashes—a spreading sense of heat from the abdomen to the thorax, neck, and face. Hot flashes may occur several times a day, sometimes accompanied by headaches resulting from the sudden vasodilation of arteries in the head. In some people, the changing hormonal profile also causes mood changes. Many physicians prescribe hormone replacement therapy (HRT)—low doses of estrogen and progesterone usually taken orally or by a skin patch—to relieve some of these symptoms. The risks and benefits of HRT are still being debated. Apply What You Know FSH and LH secretion rise at climacteric and these hormones attain high concentrations in the blood. Explain this using the preceding information and what you know about the pituitary–gonadal relationship. Menopause is the cessation of menstrual cycles, usually occurring between the ages of 45 and 55. The average age has increased steadily in the last century and is now about 52. It is difficult to precisely establish the time of menopause because the menstrual periods can stop for several months and then begin again. Menopause is generally considered to have occurred when there has been no menstruation for a year or more. DEEPER INSIGHT 28.2 Evolutionary Medicine The Evolution of Menopause There has been considerable speculation about why women do not remain fertile to the end of their lives, as men do. Some theorists argue that menopause served a biological purpose for our prehistoric foremothers. Human offspring take a long time to rear. Beyond a certain point, the frailties of age make it unlikely that a woman could rear another infant to maturity or even survive the stress of pregnancy. She might do better in the long run to become infertile and finish rearing her last child, or help to rear her grandchildren, instead of having more. In this view, menopause was biologically advantageous for our ancestors—in other words, an evolutionary adaptation. Others argue against this hypothesis on the grounds that Pleistocene (Ice Age) skeletons indicate that early hominids rarely lived past age 40. If this is true, menopause setting in at 45 to 55  years of age could have served little purpose. In this view, Pleistocene women may indeed have been fertile to the end of their lives; menopause now may be just an artifact of modern nutrition and medicine, which have made it possible for us to live much longer than our ancestors did. pro = favoring; gest = pregnancy; sterone = steroid hormone x sal78259_fm_i-xxvi.indd x 12/2/10 10:55 AM
  • ARTWORK THAT Inspires Learning CHAPTER 3 Cellular Form and Function 103 Microvilli Sets the Standard • Stunning portfolio of art and photos Microfilaments • Hundreds of accuracy reviews Terminal web Secretory vesicle in transport • Art focus groups Lysosome Desmosome Kinesin Microtubule Vivid Illustrations Rich textures and shading, and bold, bright colors bring structures to life. Intermediate filaments Intermediate filaments Microtubule in the process of assembly Centrosome Microtubule undergoing disassembly Nucleus Mitochondrion Axoneme: Peripheral microtubules Central microtubules Dynein arms (a) Basement membrane Cilia Hemidesmosome Shaft of cilium (b) FIGURE 3.25 The C Cytoskeleton. (a) Components of the cytoskeleton. Basal body (a) Plasma membrane 10 μm r re shown Few organelles are show in order to emphasize the cytoskeleton. Note that all microtubules radiate from the centrosome; they often serve as trackways for motor iate fro transp proteins (kinesin) transporting organelles. (b) Cells with their cytoskeletons labeled with fluorescent antibodies, photographed through a fluorescence microscope. a antibod typ The density of a typical cytoskeleton far exceeds even that shown in part (a). (b) 15 μm Page 103 Cilia Page 721 Axoneme Microvilli Dynein arm Central microtubule Peripheral microtubules (c) 0.15 μm (d) Page 89 The visual appeal of nature is immensely important in motivating one to study it. We certainly see this at work in human anatomy—in the countless students who describe themselves as ‘visual learners’; in the many laypeople who find anatomy atlases so intriguing; and in the enormous popularity of Body Worlds and similar exhibitions of human anatomy. (a) o ocardial V l Vortex. (a) Anterior view of –Ken Saladin um rendered transparent to expose u rende d m muscle. (b) View from the apex to ( o around oils arou the heart. This results in a u v ventricles ventricles contract. e (b) xi sal78259_fm_i-xxvi.indd xi 11/19/10 9:33 AM
  • Page 193 “The diagrams and the photographs of the human body structure bring real elements into the text and excitement for students who are being introduced to A&P for the first time.” Old club hair Epidermis Sebaceous gland Club hair (detached from matrix) Piloerector New hair Club Bulge Hair matrix Hair bulb Degeneration of lower follicle Dermis 1 Anagen (early) Anagen (mature) (Growing phase, 6–8 years) Stem cells multiply and follicle grows deeper into dermis; hair matrix cells multiply and keratinize, causing hair to grow upward; old club hair may persist temporarily alongside newly growing hair. Dermal papilla —Charmaine Irvin, Baker College of Allen Park 3 Telogen (Resting phase, 1–3 months) Dermal papilla has ascended to level of bulge; club hair falls out, usually in telogen or next anagen. 2 Catagen (Degenerative phase, 2–3 weeks) Hair growth ceases; hair bulb keratinizes and forms club hair; lower follicle degenerates. FIGURE 6 9 Page 764 TABLE 10.1 Conducive to Learning Muscles of Facial Expression (continued) Risorius24 (rih-SOR-ee-us) Depressor Anguli Oris Draws angle of mouth laterally in expressions of laughing, horror, or disdain • Easy-to-understand process figures Facial nerve O: Inferior margin of mandibular body I: Modiolus Facial nerve Draws lower lip downward and laterally in chewing and expressions of melancholy or doubt Depressor Labii Inferioris26 O: Zygomatic arch; fascia near ear I: Modiolus Draws angle of mouth laterally and downward in opening mouth or sad expressions 25 O: Mandible near mental protuberance I: Skin and mucosa of lower lip Facial nerve The Mental and Buccal Regions. Adjacent to the oral orifice are the mental region (chin) and buccal region (cheek). In addition to muscles already discussed that act directly on the lower lip, the mental region has a pair of small mentalis muscles extending from the upper margin of the mandible to the skin of the chin. In some people, these muscles are especially thick and have a visible dimple between them called the mental cleft (see fig. 4.18, p. 135). The buccinator is the muscle in the cheek. It has multiple functions in chewing, sucking, and blowing. If the cheek is inflated with air, compression of the buccinator blows it out. Sucking is achieved by contracting the buccinators to draw the cheeks inward, and then relaxing them. This action is especially important to nursing infants. To feel this action, hold your fingertips lightly on your cheeks as you make a kissing noise. You will notice the relaxation of the buccinators at the moment air is sharply drawn in through the pursed lips. The platysma is a thin superficial muscle of the upper chest and lower face. It is relatively unimportant, but when men shave they tend to tense the platysma to make the concavity between the jaw and neck shallower and the skin tauter. • Tools for students to easily orient themselves Mentalis (men-TAY-lis) Anterior Pectoralis major m. Elevates and protrudes lower lip in drinking, pouting, and expressions of doubt or disdain; elevates and wrinkles skin of chin O: Mandible near inferior incisors I: Skin of chin at mental protuberance Facial nerve Buccinator27 (BUC-sin-AY-tur) Compresses cheek against teeth and gums; directs food between molars; retracts cheek from teeth when mouth is closing to prevent biting cheek; expels air and liquid O: Alveolar processes on lateral surfaces of mandible and maxilla I: Orbicularis oris; submucosa of cheek and lips Facial nerve Platysma28 (plah-TIZ-muh) Page 390 Draws lower lip and angle of mouth downward in expressions of horror or surprise; may aid in opening Sternum mouth widely O: Fascia of deltoid and pectoralis major I: Mandible; skin and subcutaneous tissue of lower face Facial nerve Fat of breast Ventricles of heart Ribs Pericardial cavity Muscles tables are organized in new columnar format and enhanced with new shading for easier reading and learning. Right lung Esophagus Atria of heart Aorta Vertebra Left lung Spinal cord Pleural cavity 10 1 Blood enters right atrium from superior and inferior venae cavae. Posterior Aorta Left pulmonary artery 11 5 Orientation Tools Saladin art integrates tools to help students quickly orient themselves within a figure and make connections between ideas. 5 9 Pulmonary trunk Superior vena cava Right pulmonary veins 4 6 6 Left atrium 1 Aortic valve 7 3 Right atrium Left AV (bicuspid) valve 8 2 Right AV (tricuspid) valve Left ventricle 3 Contraction of right ventricle forces pulmonary valve open. 4 Blood flows through pulmonary valve into pulmonary trunk. 5 Blood is distributed by right and left pulmonary arteries to the lungs, where it unloads CO2 and loads O2. 6 Blood returns from lungs via pulmonary veins to left atrium. 7 Blood in left atrium flows through left AV valve into left ventricle. 8 Contraction of left ventricle (simultaneous with 3 step 3) ) forces aortic valve open. 9 Blood flows through aortic valve into ascending aorta. Right ventricle Inferior vena cava Left pulmonary veins 2 Blood in right atrium flows through right AV valve into right ventricle. 11 10 Blood in aorta is distributed to every organ in the body, where it unloads O2 and loads CO2. 11 Blood returns to heart via venae cavae. Process Figures Saladin breaks complicated physiological processes into numbered steps for a manageable introduction to difficult concepts. Page 721 xii sal78259_fm_i-xxvi.indd xii 11/19/10 9:34 AM
  • PEDAGOGICAL Learning Tools Engaging Chapter Layouts • Chapters are structured around the way students learn. • Frequent subheadings and expected learning outcomes help students plan their study time and review strategies. CHAPTER 12 NERVOUS TISSUE A Purkinje cell, a neuron from the cerebellum of the brain Chapter Outline provides a quick overview of the content. Deeper Insights highlight areas of interest for students. CHAPTER OUTLINE 12.1 Overview of the Nervous System 440 12.2 Properties of Neurons 441 • Universal Properties 441 • Functional Classes 442 • Structure of a Neuron 442 • Axonal Transport 445 12.3 Supportive Cells (Neuroglia) 446 • Types of Neuroglia 446 • Myelin 448 • Unmyelinated Nerve Fibers 450 • Conduction Speed of Nerve Fibers 450 • Regeneration of Nerve Fibers 450 • Neurotransmitters and Related Messengers 461 • Synaptic Transmission 463 • Cessation of the Signal 465 • Neuromodulators 465 12.6 Neural Integration 466 • Postsynaptic Potentials 466 • Summation, Facilitation, and Inhibition 467 • Neural Coding 468 • Neural Pools and Circuits 469 • Memory and Synaptic Plasticity 471 DEEPER INSIGHTS 12.1 Clinical Application: Glial Cells and Brain Tumors 447 12.2 Clinical Application: Diseases of the Myelin Sheath 448 12.3 Medical History: Nerve Growth Factor— From Home Laboratory to Nobel Prize 452 12.4 Clinical Application: Alzheimer and Parkinson Diseases 472 Connective Issues 474 Study Guide 475 12.4 Electrophysiology of Neurons 451 • Electrical Potentials and Currents 452 • The Resting Membrane Potential 453 • Local Potentials 454 • Action Potentials 455 • The Refractory Period 457 • Signal Conduction in Nerve Fibers 457 12.5 Synapses 460 • The Discovery of Neurotransmitters 460 • Structure of a Chemical Synapse 461 Module 7: Nervous System 439 xiii sal78259_fm_i-xxvi.indd xiii 11/19/10 9:34 AM
  • 750 Tiered Assessments Based on Key Learning Outcomes • Chapters are divided into easily manageable chunks, which help students budget study time effectively. • Section-ending questions allow students to check their understanding before moving on. New! Each chapter begins with Brushing Up to emphasize the interrelatedness of concepts and also provides an aid to returning, nontraditional students. Each numbered section begins with Expected Learning Outcomes to help focus the reader’s attention on the larger concepts and make the course outcome-driven. 282 PART TWO Support and Movement fibers that extend from the bone matrix of the jaw into the dental tissue (see fig. 9.2b). The periodontal ligament allows the tooth to move or give a little under the stress of chewing. This allows us to sense how hard we are biting or to sense a particle of food stuck between the teeth. the forearm. A less movable syndesmosis is the one that binds the distal ends of the tibia and fibula together, side by side (see fig. 9.2c). Syndesmoses A cartilaginous joint is also called an amphiarthrosis7 (AM-fee-ar-THRO-sis) or amphiarthrodial joint. In these joints, two bones are linked by cartilage (fig. 9.4). The two types of cartilaginous joints are synchondroses and symphyses. 6 A syndesmosis (SIN-dez-MO-sis) is a fibrous joint at which two bones are bound by relatively long collagenous fibers. The separation between the bones and length of the fibers give these joints more mobility than a suture or gomphosis has. An especially movable syndesmosis exists between the shafts of the radius and ulna, which are joined by a broad fibrous interosseous membrane. This permits such movements as pronation and supination of Cartilaginous Joints Synchondroses A synchondrosis8 (SIN-con-DRO-sis) is a joint in which the bones are bound by hyaline cartilage. An example is 7 syn = together; desm = band; osis = condition 6 Clavicle 8 PART FOUR Regulation and Maintenance Brushing Up... • The concepts of homeostatic set point and dynamic equilibrium should be reviewed (p. 17) as background for understanding the control of blood pressure. • The principles of blood volume, pressure, and flow discussed in this chapter hinge on the reasons behind the osmolarity and viscosity of blood introduced on page 682. • Familiarity with cardiac systole and diastole (p. 728) is necessary for understanding blood pressure in this chapter. • Blood flow is regulated by variations in cardiac output and blood vessel diameter, which are governed in part by the autonomic nervous system as discussed on page 576. • The exchange of materials between the blood capillaries and surrounding tissues is based on the principles of filtration, osmosis and osmotic pressure, diffusion, and transcytosis introduced earlier (pp. 91–100). crackpot because his conclusion flew in the face of common sense— if the blood was continually recirculated and not consumed by the tissues, they reasoned, then what purpose could it serve? We now know, of course, that he was right. Harvey’s case is one of the most interesting in biomedical history, for it shows how empirical science overthrows old theories and spawns better ones, and how common sense and blind allegiance to authority can interfere with the acceptance of truth. But most importantly, Harvey’s contributions represent the birth of experimental physiology. 20.1 General Anatomy of the Blood Vessels Expected Learning Outcomes When you have completed this section, you should be able to a. describe the structure of a blood vessel; T he route taken by the blood after it leaves the heart was a point of much confusion for many centuries. In traditional Chinese medicine as early as 2650 BCE, blood was believed to flow in a complete circuit around the body and back to the heart, just as we know today. But in the second century CE, Roman physician Claudius Galen (129–c. 199) argued that it flowed back and forth in the veins, like air in the bronchial tubes. He believed that the liver received food directly from the esophagus and converted it to blood, the heart pumped the blood through the veins to all other organs, and those organs consumed it. The arteries were thought to contain only a mysterious vapor or “vital spirit.” The Chinese view was right, but the first experimental demonstration of this did not come for another 4,000 years. English physician William Harvey (1578–1657) (see p. 5) studied the filling and emptying of the heart in snakes, tied off the vessels above a below the heart to observe the effects on cardiac filling and and be o output measured cardiac output in a variety of living animals, output, a estimated cardiac output in humans. He concluded that (1) and est th hea pumps more blood in half an hour than there is in the he the heart e entire b body, (2) not enough food is consumed to account for the c continu production of so much blood, and therefore (3) the blood continual re eturns returns to the heart rather than being consumed by the peripheral o organs He could not explain how, since the microscope had yet to organs. b devel be dev oped to the point that enabled Antony van Leeuwenhoek 1 1632– (1632–1723) and Marcello Malpighi (1628–94) to discover the blood c capillar capillaries. Ha Harvey’s work was the first experimental study of animal p physiol physiology and a landmark in the history of biology and medicine. B But so entrenched were the ideas of Aristotle and Galen in the me the medical community, and so strange was the idea of doing e experim experiments on living animals, that Harvey’s contemporaries re ejecte rejected his ideas. Indeed, some of them regarded him as a b. describe the different types of arteries, capillaries, and veins; c. trace the general route usually taken by the blood from the heart and back again; and d. describe some variations on this route. There are three principal categories of blood vessels: arteries, veins, and capillaries (fig. 20.1). Arteries are the efferent vessels of the cardiovascular system—that is, vessels that carry blood away from the heart. Veins are the afferent vessels that carry blood back to the heart. Capillaries are microscopic, thin-walled vessels that connect the smallest arteries to the smallest veins. Aside from their general location and direction of blood flow, these three categories of vessels also differ in the histological structure of their walls. The Vessel Wall The walls of arteries and veins are composed of three layers called tunics (fig. 20.2): 1. The tunica interna (tunica intima) lines the inside of the vessel and is exposed to the blood. It consists of a simple squamous epithelium called the endothelium overlying a basement membrane and a sparse layer of loose connective tissue; it is continuous with the endocardium of the heart. The endothelium acts as a selectively permeable barrier to materials entering or leaving the bloodstream; it secretes chemicals that stimulate dilation or constriction of the vessel; and it normally repels blood cells and platelets so that they flow freely without sticking to the vessel wall. When the endothelium is damaged, however, platelets may adhere to it and form a blood clot; and when the tissue around a vessel is inflamed, the endothelial amphi = on all sides; arthr = joined; osis = condition syn = together; chondr = cartilage; osis = condition Sternum Rib 1 Costal cartilage Intervertebral disc (fibrocartilage) (a) rim. Dislocations of the hip are rare, but some infants suffer congenital dislocations because the acetabulum is not deep enough to holdofthe head of the femur in place. If detected Body vertebra B d (c) early, this condition can be treated with a harness, worn for 2 to 4 months, that holds the head of the femur in the proper position until the joint is stronger (fig. 9.27). FIGURE 9.4 Cartilaginous Joints. (a) A synchondrosis, represented by the costal cartilage joining rib 1 to the sternum. (b) The pubic symphysis. (c) Intervertebral discs, which join adjacent vertebrae to each other by symphyses. ● What is the difference between the pubic symphysis and the interpubic disc? Interpubic disc (fibrocartilage) (b) Pubic symphysis Questions in figure legends and Apply What You Know items prompt students to think more deeply about the implications and applications of what they have learned. Apply What You Know Where else in the body is there a structure similar to the acetabular labrum? What do those two locations have in common? Ligaments that support the coxal joint include the iliofemoral (ILL-ee-oh-FEM-oh-rul) and pubofemoral (PYU-bo-FEM-or-ul) ligaments on the anterior side and the ischiofemoral (ISS-kee-oh-FEM-or-ul) ligament on the posterior side. The name of each ligament refers to  the bones to which it attaches—the femur and the ilium, pubis, or ischium. When you stand up, these ligaments become twisted and pull the head of the femur tightly into the acetabulum. The head of the femur has a conspicuous pit called the fovea capitis. The round ligament, or ligamentum teres27 (TERR-eez), arises here and attaches End-of-chapter questions build on all levels of Bloom's taxonomy in sections that: 1. assess learning outcomes 2. test simple recall and analytical thought 3. build medical vocabulary 4. apply the basic knowledge to new clinical problems and other situations xiv sal78259_fm_i-xxvi.indd xiv 12/2/10 9:18 AM
  • INNOVATIVE Chapter Sequencing Innovative Chapter Order Some chapters and topics are presented in a sequence that is more instructive than the conventional order. Early Presentation of Heredity Fundamental principles of heredity are presented in the last few pages of chapter 4 rather than at the back of the book to better integrate molecular and mendelian genetics. This organization also prepares students to learn about such genetic traits and conditions as cystic fibrosis, color blindness, blood types, hemophilia, cancer genes, or sickle-cell disease by first teaching them about dominant and recessive alleles, genotype and phenotype, and sex linkage. BRIEF About the Author iv Preface v Reviewers xxi Contents xxii Letter to the Students xxvi The functional morphology of the skeleton, joints, and muscles is treated in three consecutive chapters, 8 through 10, so when students learn muscle origins and insertions, these come only two chapters after the names of the relevant bone features. When they learn muscle actions, it is in the first chapter after learning the terms for the joint movements. This order brings another advantage: the physiology of muscle and nerve cells is treated in two consecutive chapters (11 and 12), which are thus closely integrated in their treatment of synapses, neurotransmitters, and membrane electrophysiology. Sense Organs 582 The Endocrine System 633 PART FOUR Regulation and Maintenance PART ONE Organization of the Body 1 2 3 4 5 Major Themes of Anatomy and Physiology 1 Atlas A General Orientation to Human Anatomy 28 The Chemistry of Life 42 Cellular Form and Function 78 Genetics and Cellular Function 114 Histology 143 18 19 The Circulatory System: Blood 678 The Circulatory System: The Heart 714 20 The Circulatory System: Blood Vessels and Circulation 749 The Lymphatic and Immune Systems 808 The Respiratory System 854 The Urinary System 895 Water, Electrolyte, and Acid–Base Balance 930 The Digestive System 953 Nutrition and Metabolism 1000 21 22 23 24 25 26 PART TWO Support and Movement 6 7 8 9 10 11 The Integumentary System 180 Bone Tissue 206 The Skeletal System 233 Joints 278 The Muscular System 312 Atlas B Regional and Surface Anatomy 379 Muscular Tissue 401 PART THREE Muscle Anatomy and Physiology Follow Skeleton and Joints 16 17 Contents Integration and Control 12 13 14 15 Nervous Tissue 439 The Spinal Cord, Spinal Nerves, and Somatic Reflexes 478 The Brain and Cranial Nerves 511 The Autonomic Nervous System and Visceral Reflexes 561 PART FIVE Reproduction and Development 27 28 29 The Male Reproductive System 1034 The Female Reproductive System 1064 Human Development and Aging 1102 Appendix A. Periodic Table A-1 Appendix B. Answer Keys A-3 Appendix C. Symbols of Weight and Measures A-15 Appendix D. Biomedical Abbreviations A-17 Glossary G-1 Credits C-1 Index I-1 Urinary System Presented Close to Circulatory and Respiratory Systems Most textbooks place this system near the end of the book because of its anatomical and developmental relationships with the reproductive system. However, its physiological ties to the circulatory and respiratory systems are much more important. Except for a necessary digression on lymphatics and immunity, the circulatory system is followed almost immediately with the respiratory and urinary systems. xv sal78259_fm_i-xxvi.indd xv 11/19/10 9:35 AM
  • ANOTHER LAYER TO ENHANCE THE CONNECTION The Saladin Digital Story The Complete Package Connect. Learn. Succeed. Presentation Materials: McGraw-Hill Connect assignment builder PowerPoint files with embedded animations Anatomy & Physiology Revealed PowerPoint files Digital images (stepped-out images, split images, tables, photos) Enhanced course cartridges Connect Learn L Instructor Resources Course Content MediaPhys (physiology tutorials) Laboratory manuals Virtual Labs: Web-based cat dissection Digital Resources: Ph.I.L.S. (physiology simulations) Assignable Anatomy & Physiology Revealed quizzes NEW! Anatomy & Physiology Revealed 3.0 Linking Assignable Ph.I.L.S. physiology simulations with quizzes S d Succeed Print Resources: Comprehensive instructor's guide Student Resources Ancillary correlation guide Digital Resources: Interactive eBook Anatomy & Physiology Revealed Ph.I.L.S. (physiology simulations) MediaPhys (physiology tutorials) A&P Prep (cell, chemistry, remediation) Online quizzes and learning games Animation quizzes Online tutors Print Resources: Clinical applications manual Student study guide xvi sal78259_fm_i-xxvi.indd xvi 11/19/10 9:35 AM
  • Engaging Presentation Materials for Lecture and Lab New! ConnectPlus with LearnSmart makes teaching easier and learning smarter McGraw-Hill ConnectPlus Anatomy & Physiology is a web-based assignment and assessment platform that gives students the means to better connect with their coursework, with their instructors, and with the important concepts that they will need to know for success now and in the future. With Connect Anatomy & Physiology, instructors can deliver assignments, quizzes and tests easily online. Students can practice important skills at their own pace and on their own schedule. With Connect Anatomy & Physiology Plus, students also get 24/7 online access to an eBook—an online edition of the text—to aid them in successfully completing their work, wherever and whenever they choose LearnSmart is an online diagnostic learning system that determines the level of student knowledge, and feed the student suitable content for the Anatomy & Physiology course. Students learn faster and study more effectively. As a student works within the system, LearnSmart develops a personal learning path adapted to what the student has learned and retained. LearnSmart is able to recommend additional study resources to help the student master topics. This innovative and outstanding study tool also has features for instructors where they can see exactly what students have accomplished, and a built in assessment tool for graded assignments. You can access LearnSmart through ConnectPlus. xvii sal78259_fm_i-xxvi.indd xvii 12/2/10 9:19 AM
  • Measure Your Students Progress with Assessment Tools and Assignments McGraw-Hill Higher Education and Blackboard have teamed up. Blackboard, the Web-based course-management system, has partnered with McGraw-Hill to better allow students and faculty to use online materials and activities to complement face-to-face teaching. Blackboard features exciting social learning and teaching tools that foster more logical, visually impactful and active learning opportunities for students. You’ll transform your closeddoor classrooms into communities where students remain connected to their educational experience 24 hours a day. This partnership allows you and your students access to McGraw-Hill’s Connect™ and Create™ right from within your Blackboard course – all with one single sign-on. Not only do you get single sign-on with Connect™ and Create™, you also get deep integration of McGraw-Hill content and content engines right in Blackboard. Whether you’re choosing a book for your course or building Connect™ assignments, all the tools you need are right where you want them – inside of Blackboard. Gradebooks are now seamless. When a student completes an integrated Connect™ assignment, the grade for that assignment automatically (and instantly) feeds your Blackboard grade center. McGraw-Hill and Blackboard can now offer you easy access to industry leading technology and content, whether your campus hosts it, or we do. Be sure to ask your local McGraw-Hill representative for details. xviii sal78259_fm_i-xxvi.indd xviii 12/3/10 9:45 AM
  • Anatomy & Physiology Revealed 3.0 Anatomy & Physiology Revealed is the ultimate online interactive cadaver dissection experience. Now fully customizable to fit any course or lab, this state-of-the-art program uses cadaver photos combined with a layering technique that allows the student to peel away layers of the human body to reveal structures beneath the surface. Anatomy & Physiology Revealed also offers animations, histologic and radiologic imaging, audio pronunciations, and comprehensive quizzing. It can be used as part of any one or two semester undergraduate Anatomy & Physiology or Human Anatomy course; Anatomy & Physiology Revealed is available stand-alone, or can be combined with any McGraw-Hill product. NEW! Saladin’s Anatomy & Physiology 6th edition eBook and APR 3.0—Now, Seamlessly Integrated New to this edition, the text, images, and artwork in the Saladin’s Anatomy & Physiology 6th edition are brought to life with the click of a mouse. Wherever students see the APR 3.0 logo in their eBook, they can simply click the logo and they will be taken specifically to the dissection photos, animations, histology slides, and radiological images in APR that support and enrich their understanding of the text. If you’d like to use APR in your course, but don’t have the time to create APR navigational directions for your students . . . If you’d like to use APR as a complement to your course, but don’t have the time to go through APR and choose the views that complement the text . . . We understand, and we’ve done the work for you! APR 3.0 and Saladin’s Anatomy & Physiology 6th edition are now combined into one easy-to-use, harmonious, unified system. xix sal78259_fm_i-xxvi.indd xix 12/3/10 9:45 AM
  • Provide Low-Cost Textbook Alternatives for Your Class Electronic Books Craft your teaching resources to match the way you teach! With McGraw-Hill Create™,, you can easily rearrange chapters, combine material from other content sources, and quickly upload content you have written like your course syllabus or teaching notes. Find the content you need in Create by searching through thousands of leading McGraw-Hill textbooks. Arrange your book to fit your teaching style. Create even allows you to personalize your book’s appearance by selecting the cover and adding your name, school, and course information. Order a Create book and you’ll receive a complimentary print review copy in 3–5 business days or a complimentary electronic review copy (eComp) via email in minutes. Go to today and register to experience how McGraw-Hill Create™ empowers you to teach your students your way. Other resources available: Lab Manual Options to Fit Your Course If you or your students are ready for an alternative version of the traditional textbook, McGraw-Hill eBooks offer a cheaper and eco-friendly alternative to traditional textbooks. By purchasing eBooks from McGraw-Hill, students can save as much as 50% on selected titles delivered on the most advanced eBook platform available. Contact your McGraw-Hill sales representative to discuss eBook packaging options. Create™ Student Study Guide This comprehensive study guide written by experienced instructor Jacque Homan in collaboration with Ken Saladin contains vocabulary-building and contenttesting exercises, labeling exercises, and practice exams. The Anatomy & Physiology Laboratory Manual by Eric Wise of Santa Barbara City College is expressly written to coincide with chapters of Saladin's Anatomy & Physiology. Physiology Tutorials MediaPhys offers detailed explanations, high-quality illustrations, and animations to provide students with a thorough introduction to the world of physiology— giving them a virtual tour of physiological processes. P Physiology Interactive Lab Simulations Ph.I.L.S. offers 37 lab simulations that P may be used to supplement or m substitute for wet labs. Clinical Applications Manual This manual expands on Anatomy & Physiology's clinical themes, introduces new clinical topics, and provides test questions and case studies to develop students' abilities to apply knowledge to realistic situations. A print version is available for students. New! The Laboratory Manual for Human Anatomy & Physiology by Terry Martin of Kishwaukee College is written to coincide with Saladin or any A&P textbook. • Three versions available including main, cat, and fetal pig • Includes Ph.I.L.S. 3.0 CD-ROM • Outcomes and assessments format • Clear, concise writing style Student Supplements McGraw-Hill offers various tools and technology products to support the textbook. Students can order supplemental study materials by contacting their campus bookstore or online at Instructor Supplements Instructors can obtain teaching aides by calling the McGrawHill Customer Service Department at 1-800-338-3987, visiting our online catalog at, or by contacting their local McGraw-Hill sales representative. xx sal78259_fm_i-xxvi.indd xx 11/19/10 9:35 AM
  • Reviewers Tami Asplin, North Dakota State University Jody Johnson, Arapahoe Community College Charles J. Venglarik, Jefferson State Community College Seher Atamturktur, Bronx Community College of CUNY Jamie Joseph, University of Waterloo, School of Pharmacy Janice Webster, Ivy Tech Community College Vincent Austin, Bluegrass Community and Technical College Roman Kondratov, Cleveland State University Van Wheat, South Texas College Melissa M. Bailey, Emporia State University Raymond Larsen, Bowling Green State University Jeanne K. Barnett, University of Southern Indiana Sarah Liechty, Ivy Tech Community College Board of Advisors Jerry D. Barton II, Tarrant County College-South Jo Anne Lucas, Wayne County Community College District Dr. Peter G. Bushnell, Indiana University South Bend Moges Bizuneh, Ivy Tech Community College Paul Luyster, Tarrant County College District Cindy Prentice-Craver, Chemeketa Community College Barbara A. Coles, Wake Technical Community College David E. Manry, Hillsborough Community College Dr. Timothy A Ballard, University of North Carolina Wilmington Teresa Cowan, Baker College of Clinton Township Margaret McMichael, Baton Rouge Community College Dr. Jane L. Johnson-Murray, Houston Community College Melissa A. Deadmond, Truckee Meadows Community College Kristina Miranda, Tarrant County College Vladimir Jurukovski, PhD, Suffolk County Community College Heather J. Evans Anderson, Winthrop University Greg Feitelson, Ivy Tech Community College Dean Furbish, Wake Technical Community College Deborah Furbish, Wake Technical Community College Michael Gaetz, University of Fraser Valley Anthony Gaudin, Ivy Tech Community College Matthew Geddis, Borough of Manhattan Community College-City Univof NY Elmer Godeny, Baton Rouge Community College Sylvester Hackworth, Bishop State Community College Elizabeth Hoffman, Baker College of Clinton Township Charmaine Irvin, Baker College of Allen Park Jean Jackson, Bluegrass Community and Technical College Lucia New, Saskatchewan Institute of Applied Arts & Sciences, Kelsey Campus Shirley Whitescarver, Bluegrass Community and Technical College Dale Smoak, Piedmont Technical College Scott Pallotta, Baker College at Allen Park Dr. Wanda Hargroder, Louisiana State University Glenn H. Parker, Laurentian University Martha J. Ross, Jefferson State Community College Ajay Patel, Langara College Davonya Person, Auburn University Gilbert Pitts, Austin Peay State University Dr. William A. Said, University of Georgia Ronald Slavin, Borough of Manhattan Community College-City Univ of NY Ken Smith, Arapahoe Community College Kerry L. Smith, Oakland Community College Marcia Bradley, Ocean County College Cliff Fontenot, Southeastern Louisiana University Dr. James Junker, University of Maryland Eastern Shore James Horwitz, Palm Beach Community College – Lake Worth Sonya Williams, Oklahoma City Community College Teresa Gillian, Virginia Tech Thomas Snyder, Augusta State University Bonnie J. Tarricone, Ivy Tech Community College Christine Terry, Augusta State University James F. Thompson, Austin Peay State University xxi sal78259_fm_i-xxvi.indd xxi 11/19/10 9:35 AM
  • Contents PART ONE Chapter 2 PART TWO Organization of the Body The Chemistry of Life 42 Support and Movement 2.1 Atoms, Ions, and Molecules 43 2.2 Water and Mixtures 50 2.3 Energy and Chemical Reactions 56 2.4 Organic Compounds 59 Study Guide 75 Chapter 3 Cellular Form and Function 78 Chapter 1 3.1 Concepts of Cellular Structure 79 3.2 The Cell Surface 82 3.3 Membrane Transport 91 3.4 The Cell Interior 101 Study Guide 111 Major Themes of Anatomy and Physiology 1 Chapter 4 1.1 The Scope of Anatomy and Physiology 2 1.2 The Origins of Biomedical Science 3 1.3 Scientific Method 7 1.4 Human Origins and Adaptations 9 1.5 Human Structure 12 1.6 Human Function 14 1.7 The Language of Medicine 20 1.8 Review of Major Themes 22 Study Guide 25 Genetics and Cellular Function 114 Atlas A 5.1 5.2 5.3 5.4 General Orientation to Human Anatomy 28 A.1 General Anatomical Terminology 29 A.2 Major Body Regions 31 A.3 Body Cavities and Membranes 34 A.4 Organ Systems 37 Study Guide 40 Chapter 6 The Integumentary System 180 4.1 DNA and RNA—The Nucleic Acids 115 4.2 Genes and Their Action 120 4.3 DNA Replication and the Cell Cycle 129 4.4 Chromosomes and Heredity 134 Study Guide 140 6.1 The Skin and Subcutaneous Tissue 181 6.2 Hair and Nails 190 6.3 Cutaneous Glands 195 6.4 Skin Disorders 197 Connective Issues 202 Study Guide 203 Chapter 7 Bone Tissue 206 Chapter 5 Histology 143 The Study of Tissues 144 Epithelial Tissue 146 Connective Tissue 153 Nervous and Muscular Tissues— Excitable Tissues 162 5.5 Cell Junctions, Glands, and Membranes 164 5.6 Tissue Growth, Development, Repair, and Degeneration 171 Study Guide 177 7.1 Tissues and Organs of the Skeletal System 207 7.2 Histology of Osseous Tissue 209 7.3 Bone Development 214 7.4 Physiology of Osseous Tissue 220 7.5 Bone Disorders 225 Connective Issues 229 Study Guide 230 Chapter 8 The Skeletal System 233 8.1 8.2 Overview of the Skeleton 234 The Skull 236 xxii sal78259_fm_i-xxvi.indd xxii 12/2/10 9:19 AM
  • 8.3 The Vertebral Column and Thoracic Cage 250 8.4 The Pectoral Girdle and Upper Limb 259 8.5 The Pelvic Girdle and Lower Limb 265 Study Guide 275 Chapter 9 Joints 278 9.1 9.2 9.3 Joints and Their Classification 279 Synovial Joints 283 Anatomy of Selected Diarthroses 298 Study Guide 309 11.2 Microscopic Anatomy of Skeletal Muscle 403 11.3 The Nerve–Muscle Relationship 408 11.4 Behavior of Skeletal Muscle Fibers 411 11.5 Behavior of Whole Muscles 418 11.6 Muscle Metabolism 423 11.7 Cardiac and Smooth Muscle 428 Connective Issues 435 Study Guide 436 PART THREE Integration and Control Chapter 10 The Muscular System 312 10.1 The Structural and Functional Organization of Muscles 313 10.2 Muscles of the Head and Neck 322 10.3 Muscles of the Trunk 333 10.4 Muscles Acting on the Shoulder and Upper Limb 343 10.5 Muscles Acting on the Hip and Lower Limb 359 Study Guide 375 Atlas B Regional and Surface Anatomy 379 B.1 B.2 B.3 Regional Anatomy 380 The Importance of Surface Anatomy 380 Learning Strategy 380 Chapter 11 Muscular Tissue 401 11.1 Types and Characteristics of Muscular Tissue 402 Chapter 13 The Spinal Cord, Spinal Nerves, and Somatic Reflexes 478 13.1 The Spinal Cord 479 13.2 The Spinal Nerves 487 13.3 Somatic Reflexes 500 Study Guide 508 Chapter 14 The Brain and Cranial Nerves 511 14.1 Overview of the Brain 512 14.2 Meninges, Ventricles, Cerebrospinal Fluid, and Blood Supply 516 14.3 The Hindbrain and Midbrain 521 14.4 The Forebrain 528 14.5 Integrative Functions of the Brain 534 14.6 The Cranial Nerves 546 Study Guide 558 Chapter 15 The Autonomic Nervous System and Visceral Reflexes 561 Chapter 12 Nervous Tissue 439 12.1 Overview of the Nervous System 440 12.2 Properties of Neurons 441 12.3 Supportive Cells (Neuroglia) 446 12.4 Electrophysiology of Neurons 451 12.5 Synapses 460 12.6 Neural Integration 466 Connective Issues 474 Study Guide 475 15.1 General Properties of the Autonomic Nervous System 562 15.2 Anatomy of the Autonomic Nervous System 565 15.3 Autonomic Effects on Target Organs 572 15.4 Central Control of Autonomic Function 577 Study Guide 579 Chapter 16 Sense Organs 582 16.1 Properties and Types of Sensory Receptors 583 16.2 The General Senses 585 16.3 The Chemical Senses 591 xxiii sal78259_fm_i-xxvi.indd xxiii 11/19/10 9:35 AM
  • 16.4 Hearing and Equilibrium 596 16.5 Vision 610 Study Guide 629 Chapter 17 The Endocrine System 633 17.1 Overview of the Endocrine System 634 17.2 The Hypothalamus and Pituitary Gland 637 17.3 Other Endocrine Glands 645 17.4 Hormones and Their Actions 655 17.5 Stress and Adaptation 665 17.6 Eicosanoids and Paracrine Signaling 666 17.7 Endocrine Disorders 667 Connective Issues 674 Study Guide 675 18.3 Blood Types 691 18.4 Leukocytes 696 18.5 Platelets and Hemostasis—The Control of Bleeding 702 Study Guide 711 Chapter 19 The Circulatory System: The Heart 714 19.1 Overview of the Cardiovascular System 715 19.2 Gross Anatomy of the Heart 717 19.3 Cardiac Muscle and the Cardiac Conduction System 725 19.4 Electrical and Contractile Activity of the Heart 728 19.5 Blood Flow, Heart Sounds, and the Cardiac Cycle 734 19.6 Cardiac Output 740 Study Guide 746 PART FOUR Chapter 20 Regulation and Maintenance The Circulatory System: Blood Vessels and Circulation 749 Chapter 18 The Circulatory System: Blood 678 18.1 Introduction 679 18.2 Erythrocytes 684 20.1 General Anatomy of the Blood Vessels 750 20.2 Blood Pressure, Resistance, and Flow 758 20.3 Capillary Exchange 765 20.4 Venous Return and Circulatory Shock 769 20.5 Special Circulatory Routes 771 20.6 Anatomy of the Pulmonary Circuit 772 20.7 Systemic Vessels of the Axial Region 773 20.8 Systemic Vessels of the Appendicular Region 792 Connective Issues 803 Study Guide 804 Chapter 21 The Lymphatic and Immune Systems 808 21.1 The Lymphatic System 809 21.2 Nonspecific Resistance 822 21.3 General Aspects of Specific Immunity 830 21.4 Cellular Immunity 834 21.5 Humoral Immunity 837 21.6 Immune System Disorders 843 Connective Issues 849 Study Guide 850 Chapter 22 The Respiratory System 854 22.1 Anatomy of the Respiratory System 855 22.2 Pulmonary Ventilation 866 22.3 Gas Exchange and Transport 877 22.4 Respiratory Disorders 887 Connective Issues 891 Study Guide 892 Chapter 23 The Urinary System 895 23.1 Functions of the Urinary System 896 23.2 Anatomy of the Kidney 898 23.3 Urine Formation I: Glomerular Filtration 904 23.4 Urine Formation II: Tubular Reabsorption and Secretion 910 23.5 Urine Formation III: Water Conservation 914 23.6 Urine and Renal Function Tests 918 23.7 Urine Storage and Elimination 920 Connective Issues 926 Study Guide 927 xxiv sal78259_fm_i-xxvi.indd xxiv 12/2/10 9:19 AM
  • Chapter 24 PART FIVE Chapter 29 Water, Electrolyte, and Acid–Base Balance 930 Reproduction and Development Human Development and Aging 1102 29.1 Fertilization and the Preembryonic Stage 1103 29.2 The Embryonic and Fetal Stages 1109 29.3 The Neonate 1119 29.4 Aging and Senescence 1124 Study Guide 1134 24.1 Water Balance 931 24.2 Electrolyte Balance 937 24.3 Acid–Base Balance 942 Study Guide 950 Chapter 25 The Digestive System 953 25.1 General Anatomy and Digestive Processes 954 25.2 The Mouth Through Esophagus 958 25.3 The Stomach 965 25.4 The Liver, Gallbladder, and Pancreas 974 25.5 The Small Intestine 980 25.6 Chemical Digestion and Absorption 984 25.7 The Large Intestine 990 Connective Issues 996 Study Guide 997 Chapter 26 Chapter 27 The Male Reproductive System 1034 27.1 Sexual Reproduction and Development 1035 27.2 Male Reproductive Anatomy 1040 27.3 Puberty and Climacteric 1047 27.4 Sperm and Semen 1050 27.5 Male Sexual Response 1055 Study Guide 1061 Nutrition and Metabolism 1000 Chapter 28 26.1 26.2 26.3 26.4 Appendix A: Periodic Table of the Elements A-1 Appendix B: Answer Keys A-2 Appendix C: Symbols, Weights, and Measures A-13 Appendix D: Biomedical Abbreviations A-14 Glossary G-1 Credits C-1 Index I-1 The Female Reproductive System 1064 Nutrition 1001 Carbohydrate Metabolism 1012 Lipid and Protein Metabolism 1020 Metabolic States and Metabolic Rate 1023 26.5 Body Heat and Thermoregulation 1025 Study Guide 1030 28.1 Reproductive Anatomy 1065 28.2 Puberty and Menopause 1075 28.3 Oogenesis and the Sexual Cycle 1077 28.4 Female Sexual Response 1085 28.5 Pregnancy and Childbirth 1086 28.6 Lactation 1093 Connective Issues 1098 Study Guide 1099 xxv sal78259_fm_i-xxvi.indd xxv 11/19/10 9:36 AM
  • Letter to the Students W hen I was a young boy, I became interested in what I then called “nature study” for two reasons. One was the sheer beauty of nature. I reveled in children’s books with abundant, colorful drawings and photographs of animals, plants, minerals, and gems. It was this esthetic appreciation of nature that made me want to learn more about it and made me happily surprised to discover I could make a career of it. At a slightly later age, another thing that drew me still deeper into biology was to discover writers who had a way with words—who could captivate my imagination and curiosity with their elegant prose. Once I was old enough to hold part-time jobs, I began buying zoology and anatomy books that mesmerized me with their gracefulness of writing and fascinating art and photography. I wanted to write and draw like that myself, and I began teaching myself by learning from “the masters.” I spent many late nights in my room peering into my microscope and jars of pond water, typing page after page of manuscript, and trying pen and ink as a medium. In short, I was the ultimate nerd. My “first book” was a 318-page paper on some little pond animals called hydras, with 53 India ink illustrations that I wrote for my tenth-grade biology class when I was 16. Fast-forward about 30 years, to when I became a textbook writer, and I found myself bringing that same enjoyment of writing and illustrating to the first edition of this book you are now holding. Why? Not only for its intrinsic creative satisfaction, but because I’m guessing that you’re like I was—you can appreciate a book that does more than simply give you the information you need. You appreciate, I trust, a writer who makes it enjoyable for you through his scientific, storytelling prose and his concept of the way things should be illustrated to spark interest and facilitate understanding. I know from my own students, however, that you need more than captivating illustrations and enjoyable reading. Let’s face it—A&P is a complex subject and it may seem a formidable task to acquire even a basic knowledge of the human body. It was difficult even for me to learn (and the learning never ends). So in addition to simply writing this book, I’ve given a lot of thought to its pedagogy—the art of teaching. I’ve designed my chapters to make them easier for you to study and to give you abundant opportunity to check whether you’ve understood what you read—to test yourself (as I advise my own students) before the instructor tests you. Each chapter is broken down into short, digestible bits with a set of Expected Learning Outcomes at the beginning of each section, and self-testing questions (Before You Go On) just a few pages later. Even if you have just 30 minutes to read during a lunch break or a bus ride, you can easily read or review one of these brief sections. There are also numerous self-testing questions at the end of each chapter, in some of the figure legends, and the occasional Apply What You Know questions dispersed throughout each chapter. The questions cover a broad range of cognitive skills, from simple recall of a term to your ability to evaluate, analyze, and apply what you’ve learned to new clinical situations or other problems. I hope you enjoy your study of this book, but I know there are always ways to make it even better. Indeed, what quality you may find in this edition owes a great deal to feedback I’ve received from students all over the world. If you find any typos or other errors, if you have any suggestions for improvement, if I can clarify a concept for you, or even if you just want to comment on something you really like about the book, I hope you’ll feel free to write to me. I correspond quite a lot with students and would enjoy hearing from you. Ken Saladin Georgia College & State University Milledgeville, GA 31061 (USA) xxvi sal78259_fm_i-xxvi.indd xxvi 11/19/10 9:36 AM
  • An Interactive Cadaver Dissection Experience This unique multimedia tool is designed to help you master human anatomy and physiology with: g Content customized to your course g Stunning cadaver specimens g Vivid animations g Lab practical quizzing McGraw-Hill ConnectPlusTM Anatomy & Physiology interactive learning platform provides a customizable, assignable eBook, auto-graded assessments, an adaptive diagnostic tool, lecture capture, access to instructor resources, and powerful reporting—all in an easy-to-use interface. my y my Course Content g Maximize efficiency by studying exactly what’s required. g Your instructor selects the content that’s relevant to your course. Dissection g Peel layers of the body to reveal structures beneath the surface. Animation g Over 150 animations make anatomy and physiology easier to visualize and understand. Histology g Study interactive slides that simulate what you see in lab. Imaging g Correlate dissected anatomy with X-ray, MRI, and CT scans. Quiz g Gauge proficiency with customized quizzes and lab practicals that cover only what you need for your course. Learn more at W W W. A P R E V E A L E D.C O M Full Textbook Integration! Icons throughout the book indicate specific McGraw-Hill Anatomy & Physiology|REVEALED® 3.0 content that corresponds to the text and figures. Learn Fast. Learn Easy. Learn Smart. McGraw-Hill LearnSmart™ is an adaptive diagnostic tool that constantly assesses student knowledge of course material. Sophisticated diagnostics adapt to each student’s individual knowledge base, and vary the questions to determine what the student knows, doesn’t know, knows but has forgotten, and how to best improve their knowledge level. Students actively learn required course concepts, and instructors can access specific LearnSmart reports to monitor progress. For more information, go to Saladin6e_Front_ES.indd 1 ISBN: 0073378259 Author: Saladin Title: Anatomy & Physiology, 6e Instructors can assign APR within the ConnectPlus eBook. Students can navigate directly from the ConnectPlus eBook to related APR content. 11/22/10 10:36 AM Front endsheets Color: 4 Pages: 2, 3
  • LEXICON OF BIOMEDICAL WORD ELEMENTS a- no, not, without (atom, agranulocyte) ab- away (abducens, abduction) acetabulo- small cup (acetabulum) acro- tip, extremity, peak (acromion, acromegaly) ad- to, toward, near (adsorption, adrenal) adeno- gland (lymphadenitis, adenohypophysis) aero- air, oxygen (aerobic, anaerobe, aerophagy) af- toward (afferent) ag- together (agglutination) -al pertaining to (parietal, pharyngeal, temporal) ala- wing (ala nasi) albi- white (albicans, linea alba, albino) algi- pain (analgesic, myalgia) aliment- nourishment (alimentary) allo- other, different (allele, allograft) amphi- both, either (amphiphilic, amphiarthrosis) an- without (anaerobic, anemic) ana- 1. up, build up (anabolic, anaphylaxis). 2. apart (anaphase, anatomy). 3. back (anastomosis) andro- male (androgen) angi- vessel (angiogram, angioplasty, hemangioma) ante- before, in front (antebrachium) antero- forward (anterior, anterograde) anti- against (antidiuretic, antibody, antagonist) apo- from, off, away, above (apocrine, aponeurosis) arbor- tree (arboreal, arborization) artic- 1. joint (articulation). 2. speech (articulate) -ary pertaining to (axillary, coronary) -ase enzyme (polymerase, kinase, amylase) ast-, astro- star (aster, astrocyte) -ata, -ate 1. possessing (hamate, corniculate). 2. plural of -a (stomata, carcinomata) athero- fat (atheroma, atherosclerosis) atrio- entryway (atrium, atrioventricular) auri- ear (auricle, binaural) auto- self (autolysis, autoimmune) axi- axis, straight line (axial, axoneme, axon) baro- pressure (baroreceptor, hyperbaric) bene- good, well (benign, beneficial) bi- two (bipedal, biceps, bifid) Saladin6e_Back_ES.indd 1 ISBN: 00733378259 Author: Saladin Title: Anatomy & Physiology, 6e bili- bile (biliary, bilirubin) bio- life, living (biology, biopsy, microbial) blasto- precursor, bud, producer (fibroblast, osteoblast, blastomere) brachi- arm (brachium, brachialis, antebrachium) brady- slow (bradycardia, bradypnea) bucco- cheek (buccal, buccinator) burso- purse (bursa, bursitis) calc- calcium, stone (calcaneus, hypocalcemia) callo- thick (callus, callosum) calori- heat (calorie, calorimetry, calorigenic) calv-, calvari- bald, skull (calvaria) calyx cup, vessel, chalice (glycocalyx, renal calyx) capito- head (capitis, capitate, capitulum) capni- smoke, carbon dioxide (hypocapnia) carcino- cancer (carcinogen, carcinoma) cardi- heart (cardiac, cardiology, pericardium) carot- 1. carrot (carotene). 2. stupor (carotid) carpo- wrist (carpus, metacarpal) case- cheese (caseosa, casein) cata- down, break down (catabolism) cauda- tail (cauda equina, caudate nucleus) -cel little (pedicel) celi- belly, abdomen (celiac) centri- center, middle (centromere, centriole) cephalo- head (cephalic, encephalitis) cervi- neck, narrow part (cervix, cervical) chiasm- cross, X (optic chiasm) choano- funnel (choana) chole- bile (cholecystokinin, cholelithotripsy) chondro- 1. grain (mitochondria). 2. cartilage, gristle (chondrocyte, perichondrium) chromo- color (dichromat, chromatin, cytochrome) chrono- time (chronotropic, chronic) cili- eyelash (cilium, superciliary) circ- about, around (circadian, circumduction) cis- cut (incision, incisor) cisterna reservoir (cisterna chyli) clast- break down, destroy (osteoclast) clavi- hammer, club, key (clavicle, supraclavicular) -cle little (tubercle, corpuscle) cleido- clavicle (sternocleidomastoid) cnemo- lower leg (gastrocnemius) co- together (coenzyme, cotransport) collo- 1. hill (colliculus). 2. glue (colloid, collagen) contra- opposite (contralateral) corni- horn (cornified, corniculate, cornu) corono- crown (coronary, corona, coronal) corpo- body (corpus luteum, corpora quadrigemina) corti- bark, rind (cortex, cortical) costa- rib (intercostal, subcostal) coxa- hip (os coxae, coxal) crani- helmet (cranium, epicranius) cribri- sieve, strainer (cribriform, area cribrosa) crino- separate, secrete (holocrine, endocrinology) crista- crest (crista galli, mitochondrial crista) crito- to separate (hematocrit) cruci- cross (cruciate ligament) -cule, -culus small (canaliculus, trabecula, auricular) cune- wedge (cuneiform, cuneatus) cutane-, cuti- skin (subcutaneous, cuticle) cysto- bladder (cystitis, cholecystectomy) cyto- cell (cytology, cytokinesis, monocyte) de- down (defecate, deglutition, dehydration) demi- half (demifacet, demilune) den-, denti- tooth (dentition, dens, dental) dendro- tree, branch (dendrite, oligodendrocyte) derma-, dermato- skin (dermatology, hypodermic) desmo- band, bond, ligament (desmosome, syndesmosis) dia- 1. across, through, separate (diaphragm, dialysis). 2. day (circadian) dis- 1. apart (dissect, dissociate). 2. opposite, absence (disinfect, disability) diure- pass through, urinate (diuretic, diuresis) dorsi- back (dorsal, dorsum, latissimus dorsi) duc- to carry (duct, adduction, abducens) dys- bad, abnormal, painful (dyspnea, dystrophy) e- out (ejaculate, eversion) -eal pertaining to (hypophyseal, arboreal) 11/22/10 10:33 AM Back endsheets Color: 4 process Pages: 5
  • Lexicon of Biomedical Word Elements (continued) ec-, ecto- outside, out of, external (ectopic, ectoderm, splenectomy) ef- out of (efferent, effusion) -el, -elle small (fontanel, organelle, micelle) electro- electricity (electrocardiogram, electrolyte) em- in, within (embolism, embedded) emesi-, emeti- vomiting (emetic, hyperemesis) -emia blood condition (anemia, hypoxemia) en- in, into (enzyme, parenchyma) encephalo- brain (encephalitis, telencephalon) enchymo- poured in (mesenchyme, parenchyma) endo- within, into, internal (endocrine, endocytosis) entero- gut, intestine (mesentery, myenteric) epi- upon, above (epidermis, epiphysis, epididymis) ergo- work, energy, action (allergy, adrenergic) eryth-, erythro- red (erythema, erythrocyte) esthesio- sensation, feeling (anesthesia, somesthetic) eu- good, true, normal, easy (eupnea, aneuploidy) exo- out (exopeptidase, exocytosis, exocrine) facili- easy (facilitated) fasci- band, bundle (fascia, fascicle) fenestr- window (fenestrated) fer- to carry (efferent, uriniferous) ferri- iron (ferritin, transferrin) fibro- fiber (fibroblast, fibrosis) fili- thread (myofilament, filiform) flagello- whip (flagellum) foli- leaf (folic acid, folia) -form shape (cuneiform, fusiform) fove- pit, depression (fovea) funiculo- little rope, cord (funiculus) fusi- 1. spindle (fusiform). 2. pour out (perfusion) gamo- marriage, union (monogamy, gamete) gastro- belly, stomach (gastrointestinal, digastric) -gen, -genic, -genesis producing, giving rise to (pathogen, carcinogenic, glycogenesis) genio- chin (geniohyoid, genioglossus) germi- 1. sprout, bud (germinal, germinativum). 2. microbe (germicide) gero- old age (progeria, geriatrics, gerontology) gesto- 1. to bear, carry (ingest). 2. pregnancy (gestation, progesterone) glia- glue (neuroglia, microglia) globu- ball, sphere (globulin, hemoglobin) glom- ball (glomerulus) glosso- tongue (glossopharyngeal, hypoglossal) glyco- sugar (glycogen, glycolysis, hypoglycemia) gono- 1. angle, corner (trigone). 2. seed, sex cell, generation (gonad, oogonium, gonorrhea) gradi- walk, step (retrograde, gradient) -gram recording of (electrocardiogram, sonogram) -graph recording instrument (sonograph, electrocardiograph) -graphy recording process (sonography, radiography) gravi- severe, heavy (gravid, myasthenia gravis) gyro- turn, twist (gyrus) hallu- great toe (hallux, hallucis) hemi- half (hemidesmosome, hemisphere) -hemia blood condition (polycythemia) hemo- blood (hemophilia, hemoglobin, hematology) hetero- different, other, various (heterozygous) histo- tissue, web (histology, histone) holo- whole, entire (holistic, holocrine) homeo- constant, unchanging, uniform (homeostasis, homeothermic) homo- same, alike (homologous, homozygous) hyalo- clear, glassy (hyaline, hyaluronic acid) hydro- water (dehydration, hydrolysis, hydrophobic) hyper- above, above normal, excessive (hyperkalemia, hypertonic) hypo- below, below normal, deficient (hypogastric, hyponatremia, hypophysis) -ia condition (anemia, hypocalcemia, osteomalacia) -ic pertaining to (isotonic, hemolytic, antigenic) -icle, -icul small (ossicle, canaliculus, reticular) ilia- flank, loin (ilium, iliac) -illa, -illus little (bacillus) -in protein (trypsin, fibrin, globulin) infra- below (infraspinous, infrared) ino- fiber (inotropic, inositol) insulo- island (insula, insulin) inter- between (intercellular, intervertebral) intra- within (intracellular, intraocular) iono- ion (ionotropic, cationic) ischi- to hold back (ischium, ischemia) -ism 1. process, state, condition (metabolism, rheumatism). 2. doctrine, belief, theory (holism, reductionism, naturalism) iso- same, equal (isometric, isotonic, isomer) -issimus most, greatest (latissimus, longissimus) -ite little (dendrite, somite) -itis inflammation (dermatitis, gingivitis) jug- to join (conjugated, jugular) juxta- next to (juxtamedullary, juxtaglomerular) kali- potassium (hypokalemia) karyo- seed, nucleus (megakaryocyte, karyotype) kerato- horn (keratin, keratinocyte) kine- motion, action (kinetic, kinase, cytokinesis) labi- lip (labium, levator labii) lacera- torn, cut (foramen lacerum, laceration) lacrimo- tear, cry (lacrimal gland, nasolacrimal) lacto- milk (lactose, lactation, prolactin) lamina- layer (lamina propria, laminar flow) latero- side (bilateral, ipsilateral) lati- broad (fascia lata, latissimus dorsi) Saladin6e_Back_ES.indd 2 ISBN: 00733378259 Author: Saladin Title: Anatomy & Physiology, 6e -lemma husk (sarcolemma, neurilemma) lenti- lens (lentiform) -let small (platelet) leuko- white (leukocyte, leukemia) levato- to raise (levator labii, elevation) ligo- to bind (ligand, ligament) line- line (linea alba, linea nigra) litho- stone (otolith, lithotripsy) -logy study of (histology, physiology, hematology) lucid- light, clear (stratum lucidum, zona pellucida) lun- moon, crescent (lunate, lunule, semilunar) lute- yellow (macula lutea, corpus luteum) lyso-, lyto- split apart, break down (lysosome, hydrolysis, electrolyte, hemolytic) macro- large (macromolecule, macrophage) macula- spot (macula lutea, macula densa) mali- bad (malignant, malocclusion, malformed) malle- hammer (malleus, malleolus) mammo- breast (mammary, mammillary) mano- hand (manus, manipulate) manubri- handle (manubrium) masto- breast (mastoid, gynecomastia) medi- middle (medial, mediastinum, intermediate) medullo- marrow, pith (medulla) mega- large (megakaryocyte, hepatomegaly) melano- black (melanin, melanocyte, melancholy) meno- month (menstruation, menopause) mento- chin (mental, mentalis) mero- part, segment (isomer, centromere, merocrine) meso- in the middle (mesoderm, mesentery) meta- beyond, next in a series (metaphase, metacarpal) metabol- change (metabolism, metabolite) -meter measuring device (calorimeter, spirometer) metri- 1. length, measure (isometric, emmetropic). 2. uterus (endometrium) micro- small (microscopic, microcytic, microglia) mito- thread, filament, grain (mitochondria, mitosis) mono- one (monocyte, monogamy, mononucleosis) morpho- form, shape, structure (morphology, amorphous) muta- change (mutagen, mutation) myelo- 1. spinal cord (poliomyelitis, myelin). 2. bone marrow (myeloid, myelocytic) myo-, mysi- muscle (myoglobin, myosin, epimysium) natri- sodium (hyponatremia, natriuretic) neo- new (neonatal, gluconeogenesis) nephro- kidney (nephron, hydronephrosis) neuro- nerve (aponeurosis, neurosoma, neurology) nucleo- nucleus, kernel (nucleolus, nucleic acid) oo- egg (oogenesis, oocyte) ob- 1. life (aerobic, microbe). 2. against, toward, before (obstetrics, obturator, obstruction) oculo- eye (oculi, oculomotor) odonto- tooth (odontoblast, periodontal) -oid like, resembling (colloid, sigmoid, ameboid) -ole small (arteriole, bronchiole, nucleolus) oligo- few, a little, scanty (oligopeptide, oliguria) -oma tumor, mass (carcinoma, hematoma) omo- shoulder (omohyoid, acromion) onycho- nail, claw (hyponychium, onychomycosis) op- vision (optics, myopia, photopic) -opsy viewing, to see (biopsy, rhodopsin) or- mouth (oral, orbicularis oris) orbi- circle (orbicularis, orbit) organo- tool, instrument (organ, organelle) ortho- straight (orthopnea, orthodontics, orthopedics) -ose 1. full of (adipose). 2. sugar (sucrose, glucose) -osis 1. process (osmosis, exocytosis). 2. condition, disease (cyanosis, thrombosis). 3. increase (leukocytosis) osmo- push (osmosis, chemiosmotic) osse-, oste- bone (osseous, osteoporosis) oto- ear (otolith, otitis, parotid) -ous 1. full of (nitrogenous, edematous). 2. pertaining to (mucous, nervous). 3. like, characterized by (squamous, filamentous) ovo- egg (ovum, ovary, ovulation) oxy- 1. oxygen (hypoxia, oxyhemoglobin). 2. sharp, quick (oxytocin) palli- pale (pallor, globus pallidus) palpebro- eyelid (palpebrae) pan- all (panhypopituitarism, pancreas) panni- cloth, rag (pannus, panniculus) papillo- nipple (papilla, papillary) par- birth (postpartum, parturition, multiparous) para- next to (parathyroid, parotid) parieto- wall (parietal) patho- 1. disease (pathology, pathogen). 2. feeling (sympathetic) pecto- 1. chest (pectoralis). 2. comblike (pectineus) pedi- 1. foot (bipedal, pedicle). 2. child (pediatrics) pelvi- basin (pelvis, pelvic) -penia deficiency (leukopenia, thrombocytopenia) penna- feather (unipennate, bipennate) peri- around (periosteum, peritoneum, periodontal) perone- fibula (peroneus tertius, peroneal nerve) phago- eat (phagocytosis, macrophage) philo- loving, attracted to (hydrophilic, amphiphilic) phobo- fearing, repelled by (hydrophobic) phor- to carry, bear (diaphoresis, electrophoresis) phragm- partition (diaphragm) phreno- diaphragm (phrenic nerve) physio- nature, natural cause (physiology, physician) -physis growth (diaphysis, hypophysis) pilo- hair (piloerection) pino- drink, imbibe (pinocytosis) planto- sole of foot (plantaris, plantar wart) plasi- growth (hyperplasia) plasm- shaped, molded (cytoplasm, endoplasmic) plasti- form (thromboplastin) platy- flat (platysma) pnea- breath, breathing (eupnea, dyspnea) pneumo- air, breath, lung (pneumonia, pneumothorax) podo- foot (pseudopod, podocyte) poies- forming (hemopoiesis, erythropoietin) poly- many, much, excessive (polypeptide, polyuria) primi- first (primary, primipara, primitive) pro- 1. before, in front, first (prokaryote, prophase, prostate). 2. promote, favor (progesterone, prolactin) pseudo- false (pseudopod) psycho- mind (psychosis, psychosomatic) ptero-, pterygo- wing (pterygoid) -ptosis dropping, falling, sagging (apoptosis, nephroptosis) puncto- point (puncta) pyro- fire (pyrogen, antipyretic) quadri- four (quadriceps, quadratus) quater- fourth (quaternary) radiat- radiating (corona radiata) rami- branch (ramus) recto- straight (rectus abdominis, rectum) reno- kidney (renal, renin) reti- network (reticular, rete testis) retinac- retainer, bracelet (retinaculum) retro- behind, backward (retroperitoneal, retrovirus) rhombo- rhombus (rhomboideus, rhombencephalon) rubo-, rubro- red (bilirubin, rubrospinal) rugo- fold, wrinkle (ruga, corrugator) sacculo- little sac (saccule) sarco- flesh, muscle (sarcoplasm, sarcomere) scala- staircase (scala tympani) sclero- hard, tough (sclera, sclerosis) scopo- see (microscope, endoscopy) secto- cut (section, dissection) semi- half (semilunar, semimembranosus) sepsi- infection (asepsis, septicemia) -sis process (diapedesis, amniocentesis) sole- sandal, sole of foot, flatfish (sole, soleus) soma-, somato- body (somatic, somatotropin) spheno- wedge (sphenoid) spiro- breathing (inspiration, spirometry) splanchno- viscera (splanchnic) spleno- 1. bandage (splenius capitis). 2. spleen (splenic artery) squamo- scale, flat (squamous, desquamation) stasi-, stati- put, remain, stay the same (hemostasis, homeostatic) steno- narrow (stenosis) ster-, stereo- solid, three-dimensional (steroid, stereoscopic) sterno- breast, chest (sternum, sternocleidomastoid) stria- stripe (striated, corpus striatum) sub- below (subcutaneous, subclavicular) sulc- furrow, groove (sulcus) supra- above (supraspinous, supraclavicular) sura- calf of leg (triceps surae) sym- together (sympathetic, symphysis) syn- together (synostosis, syncytium) tachy- fast (tachycardia, tachypnea) tarsi- ankle (tarsus, metatarsal) tecto- roof, cover (tectorial membrane, tectum) telo- last, end (telophase, telencephalon, telodendria) tempo- time (temporal) terti- third (tertiary) theli- nipple, female, tender (epithelium, polythelia) thermo- heat (thermogenesis, thermoregulation) thrombo- blood clot (thrombosis, thrombin) thyro- shield (thyroid, thyrohyoid) -tion process (circulation, pronation) toci- birth (oxytocin) tomo- 1. cut (tomography, atom, anatomy). 2. segment (dermatome, myotome, sclerotome) tono- force, tension (isotonic, tonus, myotonia) topo- place, position (isotope, ectopic) trabo- plate (trabecula) trans- across (transpiration, transdermal) trapezi- 1. table, grinding surface (trapezium). 2. trapezoid (trapezius) tri- three (triceps, triglyceride) tricho- hair (trichosiderin, peritrichial) trocho- wheel, pulley (trochlea) troph- 1. food, nourishment (trophic, trophoblast). 2. growth (dystrophy, hypertrophy) tropo- to turn, change (metabotropic, gonadotropin) tunica- coat (tunica intima, tunica vaginalis) tympano- drum, eardrum (tympanic, tensor tympani) -ul small (trabecula, tubule, capitulum, glomerulus) -uncle, -unculus small (homunculus, caruncle) uni- one (unipennate, unipolar) uri- urine (glycosuria, urinalysis, diuretic) utriculo- little bag (utriculus) vagino- sheath (invaginate, tunica vaginalis) vago- wander (vagus) vaso- vessel (vascular, vas deferens, vasa recta) ventro- belly, lower part (ventral, ventricle) vermi- worm (vermis, vermiform appendix) vertebro- spine (vertebrae, intervertebral) vesico- bladder, blister (vesical, vesicular) villo- hair, hairy (microvillus) vitre- glass (in vitro, vitreous humor) vivi- life, alive (in vivo, revive) zygo- union, join, mate (zygomatic, zygote, azygos) 11/22/10 10:33 AM Back endsheets Color: 4 process Pages: 6, 7
  • CHAPTER 1 MAJOR THEMES OF ANATOMY AND PHYSIOLOGY A new life begins—a human embryo on the point of a pin CHAPTER OUTLINE 1.1 The Scope of Anatomy and Physiology 2 • Anatomy—The Study of Form 2 • Physiology—The Study of Function 3 1.2 The Origins of Biomedical Science 3 • The Greek and Roman Legacy 3 • The Birth of Modern Medicine 4 • Living in a Revolution 6 1.3 Scientific Method 7 • The Inductive Method 7 • The Hypothetico–Deductive Method 8 • Experimental Design 8 • Peer Review 8 • Facts, Laws, and Theories 9 1.4 Human Origins and Adaptations 9 • Evolution, Selection, and Adaptation 10 • Our Basic Primate Adaptations 10 • Walking Upright 11 1.5 Human Structure 12 • The Hierarchy of Complexity 12 • Anatomical Variation 14 1.6 Human Function 14 • Characteristics of Life 15 • Physiological Variation 16 • Homeostasis and Negative Feedback 16 • Positive Feedback and Rapid Change 18 1.7 The Language of Medicine 20 • The History of Anatomical Terminology 20 • Analyzing Medical Terms 20 • Plural, Adjectival, and Possessive Forms 21 • Pronunciation 22 • The Importance of Precision 22 DEEPER INSIGHTS 1.1 Evolutionary Medicine: Vestiges of Human Evolution 10 1.2 Clinical Application: Situs Inversus and Other Unusual Anatomy 14 1.3 Medical History: Men in the Oven 18 1.4 Medical History: Obscure Word Origins 21 1.5 Clinical Application: Medical Imaging 23 1.8 Review of Major Themes 22 Study Guide 25 Module 1: Body Orientation 1 sal78259_ch01_001-027.indd 1 11/2/10 9:05 AM
  • 2 PART ONE Organization of the Body N o branch of science hits as close to home as the science of our own bodies. We’re grateful for the dependability of our hearts; we’re awed by the capabilities of muscles and joints displayed by Olympic athletes; and we ponder with philosophers the ancient mysteries of mind and emotion. We want to know how our body works, and when it malfunctions, we want to know what is happening and what we can do about it. Even the most ancient writings of civilization include medical documents that attest to humanity’s timeless drive to know itself. You are embarking on a subject that is as old as civilization, yet one that grows by thousands of scientific publications every week. This book is an introduction to human structure and function, the biology of the human body. It is meant primarily to give you a foundation for advanced study in health care, exercise physiology, pathology, and other fields related to health and fitness. Beyond that purpose, however, it can also provide you with a deeply satisfying sense of self-understanding. As rewarding and engrossing as this subject is, the human body is highly complex, and understanding it requires us to comprehend a great deal of detail. The details will be more manageable if we relate them to a few broad, unifying concepts. The aim of this chapter, therefore, is to introduce such concepts and put the rest of the book into perspective. We consider the historical development of anatomy and physiology, the thought processes that led to the knowledge in this book, the meaning of human life, a central concept of physiology called homeostasis, and how to better understand medical terminology. Anatomy—The Study of Form There are several ways to examine the structure of the human body. The simplest is inspection—simply looking at the body’s appearance, as in performing a physical examination or making a clinical diagnosis from surface appearance. Physical examinations also involve touching and listening to the body. Palpation1 means feeling a structure with the hands, such as palpating a swollen lymph node or taking a pulse. Auscultation2 (AWS-cul-TAY-shun) is listening to the natural sounds made by the body, such as heart and lung sounds. In percussion, the examiner taps on the body, feels for abnormal resistance, and listens to the emitted sound for signs of abnormalities such as pockets of fluid or air. But a deeper understanding of the body depends on dissection (dis-SEC-shun)—the careful cutting and separation of tissues to reveal their relationships. The very words anatomy3 and dissection4 both mean “cutting apart”; until the nineteenth century, dissection was called “anatomizing.” In many schools of health science, one of the first steps in the training of students is dissection of the cadaver,5 a dead human body (fig. 1.1). Many insights into human structure are obtained from comparative anatomy—the study of more than one species in order to examine structural similarities and differences and analyze evolutionary trends. Anatomy students often begin by dissecting other animals with which we share a common ancestry and many structural similarities. Many of the reasons for human structure become apparent only when we look at the structure of other animals. 1.1 The Scope of Anatomy and Physiology Expected Learning Outcomes When you have completed this section, you should be able to a. define anatomy and physiology and relate them to each other; b. describe several ways of studying human anatomy; and c. define a few subdisciplines of human physiology. Anatomy is the study of structure, and physiology is the study of function. These approaches are complementary and never entirely separable. Together, they form the bedrock of the health sciences. When we study a structure, we want to know, What does it do? Physiology thus lends meaning to anatomy; and, conversely, anatomy is what makes physiology possible. This unity of form and function is an important point to bear in mind as you study the body. Many examples of it will be apparent throughout the book—some of them pointed out for you, and others you will notice for yourself. sal78259_ch01_001-027.indd 2 FIGURE 1.1 Early Medical Students in the Gross Anatomy Laboratory with Three Cadavers. ● Why should medical students study more than one cadaver? palp = touch, feel; ation = process auscult = listen; ation = process 3 ana = apart; tom = cut 4 dis = apart; sect = cut 5 from cadere = to fall down or die 1 2 11/2/10 9:05 AM
  • CHAPTER 1 Dissection, of course, is not the method of choice when studying a living person! It was once common to diagnose disorders through exploratory surgery—opening the body and taking a look inside to see what was wrong and what could be done about it. Any breach of the body cavities is risky, however, and most exploratory surgery has now been replaced by medical imaging techniques— methods of viewing the inside of the body without surgery, discussed at the end of this chapter (see Deeper Insight 1.5). The branch of medicine concerned with imaging is called radiology. Structure that can be seen with the naked eye—whether by surface observation, radiology, or dissection—is called gross anatomy. Ultimately, the functions of the body result from its individual cells. To see those, we usually take tissue specimens, thinly slice and stain them, and observe them under the microscope. This approach is called histology6 (microscopic anatomy). Histopathology is the microscopic examination of tissues for signs of disease. Cytology7 is the study of the structure and function of individual cells. Ultrastructure refers to fine detail, down to the molecular level, revealed by the electron microscope. Physiology—The Study of Function Physiology8 uses the methods of experimental science discussed later. It has many subdisciplines such as neurophysiology (physiology of the nervous system), endocrinology (physiology of hormones), and pathophysiology (mechanisms of disease). Partly because of limitations on experimentation with humans, much of what we know about bodily function has been gained through comparative physiology, the study of how different species have solved problems of life such as water balance, respiration, and reproduction. Comparative physiology is also the basis for the development of new drugs and medical procedures. For example, a cardiac surgeon may have to learn animal surgery before practicing on humans, and a vaccine cannot be used on human subjects until it has been demonstrated through animal research that it confers significant benefits without unacceptable risks. Before You Go On Answer the following questions to test your understanding of the preceding section: 1. What is the difference between anatomy and physiology? How do these two sciences support each other? 2. Name the method that would be used for each of the following: listening to a patient for a heart murmur; studying the microscopic structure of the liver; microscopically examining liver tissue for signs of hepatitis; learning the blood vessels of a cadaver; and performing a breast self-examination. histo = tissue; logy = study of cyto = cell; logy = study of 8 physio = nature; logy = study of 6 7 sal78259_ch01_001-027.indd 3 Major Themes of Anatomy and Physiology 3 1.2 The Origins of Biomedical Science Expected Learning Outcomes When you have completed this section, you should be able to a. give examples of how modern biomedical science emerged from an era of superstition and authoritarianism; and b. describe the contributions of some key people who helped to bring about this transformation. Any science is more enjoyable if we consider not just the current state of knowledge, but how it compares to past understandings of the subject and how our knowledge was gained. Of all sciences, medicine has one of the most fascinating histories. Medical science has progressed far more in the last 50 years than in the 2,500 years before that, but the field did not spring up overnight. It is built upon centuries of thought and controversy, triumph and defeat. We cannot fully appreciate its present state without understanding its past—people who had the curiosity to try new things, the vision to look at human form and function in new ways, and the courage to question authority. The Greek and Roman Legacy As early as 3,000 years ago, physicians in Mesopotamia and Egypt treated patients with herbal drugs, salts, physical therapy, and faith healing. The “father of medicine,” however, is usually considered to be the Greek physician Hippocrates (c. 460–c. 375 BCE). He and his followers established a code of ethics for physicians, the Hippocratic Oath, that is still recited in modern form by many graduating medical students. Hippocrates urged physicians to stop attributing disease to the activities of gods and demons and to seek their natural causes, which could afford the only rational basis for therapy. Aristotle (384–322 BCE) was one of the first philosophers to write about anatomy and physiology. He believed that diseases and other natural events could have either supernatural causes, which he called theologi, or natural ones, which he called physici or physiologi. We derive such terms as physician and physiology from the latter. Until the nineteenth century, physicians were called “doctors of physic.” In his anatomy book, On the Parts of Animals, Aristotle tried to identify unifying themes in nature. Among other points, he argued that complex structures are built from a smaller variety of simple components—a perspective that we will find useful later in this chapter. Apply What You Know When you have completed this chapter, discuss the relevance of Aristotle’s philosophy to our current thinking about human structure. 11/2/10 9:06 AM
  • 4 PART ONE Organization of the Body Claudius Galen (c. 130–c. 200), physician to the Roman gladiators, wrote the most influential medical textbook of the ancient era—a book that was worshipped to excess by medical professors for centuries to follow. Cadaver dissection was banned in Galen’s time because of some horrid excesses that preceded him, including public dissection of living slaves and prisoners. Aside from what he could learn by treating the gladiators’ wounds, Galen was therefore limited to dissecting pigs, monkeys, and other animals. Because he was not permitted to dissect cadavers, he had to guess at much of human anatomy and made some incorrect deductions from animal dissections. He described the human liver, for example, as having five fingerlike lobes, somewhat like a baseball glove, because that is what he had seen in baboons. But Galen saw science as a method of discovery, not as a body of fact to be taken on faith. He warned that even his own books could be wrong and advised his followers to trust their own observations more than they trusted any book. Unfortunately, his advice was not heeded. For nearly 1,500 years, medical professors dogmatically taught what they read in Aristotle and Galen, seldom daring to question the authority of these “ancient masters.” The Birth of Modern Medicine In the Middle Ages, the state of medical science varied greatly from one religious culture to another. Science was severely repressed in the Christian culture of Europe until about the sixteenth century, although some of the most famous medical schools of Europe were founded during this era. Their professors, however, taught medicine primarily as a dogmatic commentary on Galen and Aristotle, not as a field of original research. Medieval medical illustrations were crude representations of the body intended more to decorate a page than to depict the body realistically. Some were astrological charts that showed which sign of the zodiac was thought to influence each organ of the body (fig. 1.2). From such pseudoscience came the word influenza, Italian for “influence.” Free inquiry was less inhibited in Jewish and Muslim culture during this time. Jewish physicians were the most esteemed practitioners of their art—and none more famous than Moses ben Maimon (1135–1204), known in Christendom as Maimonides. Born in Spain, he fled to Egypt at age 24 to escape antisemitic persecution. There he served the rest of his life as physician to the court of the sultan, Saladin. A highly admired rabbi, Maimonides wrote voluminously on Jewish law and theology, but also wrote 10 influential medical books and numerous treatises on specific diseases. Among Muslims, probably the most highly regarded medical scholar was Ibn Sina (980–1037), known in the West as Avicenna or “the Galen of Islam.” He studied Galen and Aristotle, combined their findings with original discoveries, sal78259_ch01_001-027.indd 4 FIGURE 1.2 Zodiacal Man. This illustration from a fifteenth-century medical manuscript reflects the medieval belief in the influence of astrology on parts of the body. ● How does the word influenza stem from the belief reflected by this illustration? and questioned authority when the evidence demanded it. Medicine in the Mideast soon became superior to European medicine. Avicenna’s textbook, The Canon of Medicine, was the leading authority in European medical schools for over 500 years. Chinese medicine had little influence on Western thought and practice until relatively recently; the medical arts evolved in China quite independently of European medicine. Later chapters of this book describe some of the medical and anatomical insights of ancient China and India. Modern Western medicine began around the sixteenth century in the innovative minds of such people as the anatomist Andreas Vesalius and the physiologist William Harvey. Andreas Vesalius (1514–64) 11/2/10 9:06 AM
  • CHAPTER 1 taught anatomy in Italy. In his time, the Catholic Church relaxed its prohibition against cadaver dissection, primarily to allow autopsies in cases of suspicious death. Furthermore, the Italian Renaissance created an environment more friendly to innovative scholarship. Dissection gradually found its way into the training of medical students throughout Europe. It was an unpleasant business, however, and most professors considered it beneath their dignity. In those days before refrigeration or embalming, the odor from the decaying cadaver was unbearable. Dissections were conducted outdoors in a nonstop 4-day race against decay. Bleary medical students had to fight the urge to vomit, lest they incur the wrath of an overbearing professor. Professors typically sat in an elevated chair, the cathedra, reading dryly in Latin from Galen or Aristotle while a lower-ranking barber–surgeon removed putrefying organs from the cadaver and held them up for the students to see. Barbering and surgery were considered to be “kindred arts of the knife”; today’s barber poles date from this era, their red and white stripes symbolizing blood and bandages. Vesalius broke with tradition by coming down from the cathedra and doing the dissections himself. He was quick to point out that much of the anatomy in Galen’s books was wrong, and he was the first to publish accurate illustrations for teaching anatomy (fig. 1.3). When others began to plagiarize his illustrations, Vesalius published the first atlas of anatomy, De Humani Corporis Fabrica (On the Structure of the Human Body), in 1543. This book began a rich tradition of medical illustration that has been handed down to us through such milestones as Gray’s Anatomy (1856) and the vividly illustrated atlases and textbooks of today. Anatomy preceded physiology and was a necessary foundation for it. What Vesalius was to anatomy, the Englishman William Harvey (1578–1657) was to physiology. Harvey is remembered especially for his studies of blood circulation and a little book he published in 1628, known by its abbreviated title De Motu Cordis (On the Motion of the Heart). He and Michael Servetus (1511–53) were the first Western scientists to realize that blood must circulate continuously around the body, from the heart to the other organs and back to the heart again. This flew in the face of Galen’s belief that the liver converted food to blood, the heart pumped blood through the veins to all other organs, and those organs consumed it. Harvey’s colleagues, wedded to the ideas of Galen, ridiculed him for his theory, though we now know he was correct (see p. 750). Despite persecution and setbacks, Harvey lived to a ripe old age, served as physician to the kings of England, and later did important work in embryology. Most importantly, Harvey’s contributions represent the birth of experimental physiology—the method that generated most of the information in this book. Modern medicine also owes an enormous debt to two inventors from this era, Robert Hooke and Antony van sal78259_ch01_001-027.indd 5 Major Themes of Anatomy and Physiology 5 FIGURE 1.3 The Art of Vesalius. Andreas Vesalius revolutionized medical illustration with the comparatively realistic art prepared for his 1543 book, De Humani Corporis Fabrica. Leeuwenhoek, who extended the vision of biologists to the cellular level. Robert Hooke (1635–1703), an Englishman, designed scientific instruments of various kinds and made many improvements in the compound microscope. This is a tube with a lens at each end—an objective lens near the specimen, which produces an initial magnified image, and an ocular lens (eyepiece) near the observer’s eye, which magnifies the first image still further. Although crude compound microscopes had existed since 1595, Hooke improved the optics and invented several of the helpful features found in microscopes today—a stage to hold the specimen, an illuminator, and coarse and fine focus controls. His microscopes magnified only about 30 times, but with them, he was the first to see and name cells. In 1663, he observed thin shavings of cork and observed that they “consisted of a great many little boxes,” which he called cellulae (little cells) after 11/2/10 9:06 AM
  • 6 PART ONE (a) Organization of the Body (b) FIGURE 1.4 Hooke’s Compound Microscope. (a) The compound microscope had a lens at each end of a tubular body. (b) Hooke’s drawing of cork cells, showing the thick cell walls characteristic of plants. the cubicles of a monastery (fig. 1.4). He later observed thin slices of fresh wood and saw living cells “filled with juices.” Hooke became particularly interested in microscopic examination of such material as insects, plant tissues, and animal parts. He published the first comprehensive book of microscopy, Micrographia, in 1665. Antony van Leeuwenhoek (an-TOE-nee vahn LAY-wenhook) (1632–1723), a Dutch textile merchant, invented a simple (single-lens) microscope, originally for the purpose of examining the weave of fabrics. His microscope was a beadlike lens mounted in a metal plate equipped with a movable specimen clip. Even though his microscopes were simpler than Hooke’s, they achieved much greater useful magnification (up to 200×) owing to Leeuwenhoek’s superior lens-making technique. Out of curiosity, he examined a drop of lake water and was astonished to find a variety of microorganisms—“little animalcules,” he called them, “very prettily a-swimming.” He went on to observe practically everything he could get his hands on, including blood cells, blood capillaries, sperm, muscular tissue, and bacteria from tooth scrapings. Leeuwenhoek began submitting his observations to the Royal Society of London in 1673. He was praised at first, and his observations were sal78259_ch01_001-027.indd 6 eagerly read by scientists, but enthusiasm for the microscope did not last. By the end of the seventeenth century, it was treated as a mere toy for the upper classes, as amusing and meaningless as a kaleidoscope. Leeuwenhoek and Hooke had even become the brunt of satire. But probably no one in history had looked at nature in such a revolutionary way. By taking biology to the cellular level, the two men had laid an entirely new foundation for the modern medicine to follow centuries later. The Hooke and Leeuwenhoek microscopes produced poor images with blurry edges (spherical aberration) and rainbowlike distortions (chromatic aberration). These problems had to be solved before the microscope could be widely used as a biological tool. In nineteenth-century Germany, Carl Zeiss (1816–88) and his business partner, physicist Ernst Abbe (1840–1905), greatly improved the compound microscope, adding the condenser and developing superior optics. With improved microscopes, biologists began eagerly examining a wider variety of specimens. By 1839, botanist Matthias Schleiden (1804–81) and zoologist Theodor Schwann (1810–82) concluded that all organisms were composed of cells. Although it took another century for this idea to be generally accepted, it became the first tenet of the cell theory, added to by later biologists and summarized in chapter 3. The cell theory was perhaps the most important breakthrough in biomedical history; all functions of the body are now interpreted as the effects of cellular activity. Although the philosophical foundation for modern medicine was largely established by the time of Leeuwenhoek, Hooke, and Harvey, clinical practice was still in a dismal state. Few doctors attended medical school or received any formal education in basic science or human anatomy. Physicians tended to be ignorant, ineffective, and pompous. Their practice was heavily based on expelling imaginary toxins from the body by bleeding their patients or inducing vomiting, sweating, or diarrhea. They performed operations with filthy hands and instruments, spreading lethal infections from one patient to another and refusing, in their vanity, to believe that they themselves were the carriers of disease. Countless women died of infections acquired during childbirth from their obstetricians. Fractured limbs often became gangrenous and had to be amputated, and there was no anesthesia to lessen the pain. Disease was still widely attributed to demons and witches, and many people felt they would be interfering with God’s will if they tried to treat it. Living in a Revolution This short history brings us only to the threshold of modern biomedical science; it stops short of such momentous discoveries as the germ theory of disease, the mechanisms of heredity, and the structure of DNA. In the twentieth century, basic biology and biochemistry 11/2/10 9:06 AM
  • CHAPTER 1 yielded a much deeper understanding of how the body works. Advances in medical imaging have enhanced our diagnostic ability and life-support strategies. We have witnessed monumental developments in chemotherapy, immunization, anesthesia, surgery, organ transplants, and human genetics. By the close of the twentieth century, we had discovered the chemical “base sequence” of every human gene and begun attempting gene therapy to treat children born with diseases recently considered incurable. As future historians look back on the turn of this century, they may exult about the Genetic Revolution in which you are now living. Several discoveries of the nineteenth and twentieth centuries, and the men and women behind them, are covered in short historical sketches in later chapters. Yet, the stories told in this chapter are different in a significant way. The people discussed here were pioneers in establishing the scientific way of thinking. They helped to replace superstition with an appreciation of natural law. They bridged the chasm between mystery and medication. Without this intellectual revolution, those who followed could not have conceived of the right questions to ask, much less a method for answering them. Before You Go On Answer the following questions to test your understanding of the preceding section: 3. In what way did the followers of Galen disregard his advice? How does Galen’s advice apply to you and this book? 4. Describe two ways in which Vesalius improved medical education and set standards that remain relevant today. 5. How is our concept of human form and function today affected by inventors from Hooke to Zeiss? 1.3 Scientific Method Expected Learning Outcomes When you have completed this section, you should be able to a. describe the inductive and hypothetico–deductive methods of obtaining scientific knowledge; b. describe some aspects of experimental design that help to ensure objective and reliable results; and c. explain what is meant by hypothesis, fact, law, and theory in science. Prior to the seventeenth century, science was done in a haphazard way by a small number of isolated individuals. The philosophers Francis Bacon (1561–1626) in England and René Descartes (1596–1650) in France envisioned science as a far greater, systematic enterprise with enormous possibilities for human health and welfare. They sal78259_ch01_001-027.indd 7 Major Themes of Anatomy and Physiology 7 detested those who endlessly debated ancient philosophy without creating anything new. Bacon argued against biased thinking and for more objectivity in science. He outlined a systematic way of seeking similarities, differences, and trends in nature and drawing useful generalizations from observable facts. You will see echoes of Bacon’s philosophy in the discussion of scientific method that follows. Though the followers of Bacon and Descartes argued bitterly with one another, both men wanted science to become a public, cooperative enterprise, supported by governments and conducted by an international community of scholars rather than a few isolated amateurs. Inspired by their vision, the French and English governments established academies of science that still flourish today. Bacon and Descartes are credited with putting science on the path to modernity, not by discovering anything new in nature or inventing any techniques—for neither man was a scientist—but by inventing new habits of scientific thought. When we say “scientific,” we mean that such thinking is based on assumptions and methods that yield reliable, objective, testable information about nature. The assumptions of science are ideas that have proven fruitful in the past—for example, the idea that natural phenomena have natural causes and nature is therefore predictable and understandable. The methods of science are highly variable. Scientific method refers less to observational procedures than to certain habits of disciplined creativity, careful observation, logical thinking, and honest analysis of one’s observations and conclusions. It is especially important in health science to understand these habits. This field is littered with more fads and frauds than any other. We are called upon constantly to judge which claims are trustworthy and which are bogus. To make such judgments depends on an appreciation of how scientists think, how they set standards for truth, and why their claims are more reliable than others. The Inductive Method The inductive method, first prescribed by Bacon, is a process of making numerous observations until one feels confident in drawing generalizations and predictions from them. What we know of anatomy is a product of the inductive method. We describe the normal structure of the body based on observations of many bodies. This raises the issue of what is considered proof in science. We can never prove a claim beyond all possible refutation. We can, however, consider a statement as proven beyond reasonable doubt if it was arrived at by reliable methods of observation, tested and confirmed repeatedly, and not falsified by any credible observation. In science, all truth is tentative; there is no room for dogma. We must always be prepared to abandon yesterday’s truth if tomorrow’s facts disprove it. 11/2/10 9:06 AM
  • 8 PART ONE Organization of the Body The Hypothetico–Deductive Method A control group consists of subjects that are as much like the treatment group as possible except with respect to the variable being tested. For example, there is evidence that garlic lowers blood cholesterol levels. In one study, volunteers with high cholesterol were each given 800 mg of garlic powder daily for 4 months and exhibited an average 12% reduction in cholesterol. Was this a significant reduction, and was it due to the garlic? It is impossible to say without comparison to a control group of similar people who received no treatment. In this study, the control group averaged only a 3% reduction in cholesterol, so garlic seems to have made a difference. Most physiological knowledge was obtained by the hypothetico–deductive method. An investigator begins by asking a question and formulating a hypothesis—an educated speculation or possible answer to the question. A good hypothesis must be (1) consistent with what is already known and (2) capable of being tested and possibly falsified by evidence. Falsifiability means that if we claim something is scientifically true, we must be able to specify what evidence it would take to prove it wrong. If nothing could possibly prove it wrong, then it is not scientific. Apply What You Know The ancients thought that gods or invisible demons caused epilepsy. Today, epileptic seizures are attributed to bursts of abnormal electrical activity in nerve cells of the brain. Explain why one of these claims is falsifiable (and thus scientific), whereas the other claim is not. The purpose of a hypothesis is to suggest a method for answering a question. From the hypothesis, a researcher makes a deduction, typically in the form of an “if–then” prediction: If my hypothesis on epilepsy is correct and I record the brain waves of patients during seizures, then I  should observe abnormal bursts of activity. A properly conducted experiment yields observations that either support a hypothesis or require the scientist to modify or abandon it, formulate a better hypothesis, and test that one. Hypothesis testing operates in cycles of conjecture and disproof until one is found that is supported by the evidence. • Psychosomatic effects. Psychosomatic effects (effects of the subject’s state of mind on his or her physiology) can have an undesirable effect on experimental results if we do not control for them. In drug research, it is therefore customary to give the control group a placebo (pla-SEE-bo)—a substance with no significant physiological effect on the body. If we were testing a drug, for example, we could give the treatment group the drug and the control group identical-looking sugar tablets. Neither group must know which tablets it is receiving. If the two groups showed significantly different effects, we could feel confident that it did not result from a knowledge of what they were taking. • Experimenter bias. In the competitive, high-stakes world of medical research, experimenters may want certain results so much that their biases, even subconscious ones, can affect their interpretation of the data. One way to control for this is the doubleblind method. In this procedure, neither the subject to whom a treatment is given nor the person giving it and recording the results knows whether that subject is receiving the experimental treatment or placebo. A researcher might prepare identical-looking tablets, some with the drug and some with placebo; label them with code numbers; and distribute them to participating physicians. The physicians themselves do not know whether they are administering drug or placebo, so they cannot give the subjects even accidental hints of which substance they are taking. When the data are collected, the researcher can correlate them with the composition of the tablets and determine whether the drug had more effect than the placebo. • Statistical testing. If you tossed a coin 100 times, you would expect it to come up about 50 heads and 50 tails. If it actually came up 48:52, you would probably attribute this to random error rather than bias in the coin. But what if it came up 40:60? At what point would you begin to suspect bias? This type of problem is faced routinely in research—how great a difference must there be Experimental Design Doing an experiment properly involves several important considerations. What shall I measure and how can I measure it? What effects should I watch for and which ones should I ignore? How can I be sure that my results are due to the factors (variables) that I manipulate and not due to something else? When working on human subjects, how can I prevent the subject’s expectations or state of mind from influencing the results? Most importantly, how can I eliminate my own biases and be sure that even the most skeptical critics will have as much confidence in my conclusions as I do? Several elements of experimental design address these issues: • • Sample size. The number of subjects (animals or people) used in a study is the sample size. An adequate sample size controls for chance events and individual variations in response and thus enables us to place more confidence in the outcome. For example, would you rather trust your health to a drug that was tested on 5 people or one tested on 5,000? Why? Controls. Biomedical experiments require comparison between treated and untreated individuals so that we can judge whether the treatment has any effect. sal78259_ch01_001-027.indd 8 11/2/10 9:06 AM
  • CHAPTER 1 between control and experimental groups before we feel confident that it was due to the treatment and not merely random variation? What if a treatment group exhibited a 12% reduction in cholesterol level and the placebo group a 10% reduction? Would this be enough to conclude that the treatment was effective? Scientists are well grounded in statistical tests that can be applied to the data. Perhaps you have heard of the chi-square test, the t test, or analysis of variance, for example. A typical outcome of a statistical test might be expressed, “We can be 99.5% sure that the difference between group A and group B was due to the experimental treatment and not to random variation.” Science is grounded not in statements of absolute truth, but in statements of probability. Peer Review When a scientist applies for funds to support a research project or submits results for publication, the application or manuscript is submitted to peer review—a critical evaluation by other experts in that field. Even after a report is published, if the results are important or unconventional, other scientists may attempt to reproduce them to see if the author was correct. At every stage from planning to postpublication, scientists are therefore subject to intense scrutiny by their colleagues. Peer review is one mechanism for ensuring honesty, objectivity, and quality in science. Facts, Laws, and Theories The most important product of scientific research is understanding how nature works—whether it be the nature of a pond to an ecologist or the nature of a liver cell to a physiologist. We express our understanding as facts, laws, and theories of nature. It is important to appreciate the differences among these. A scientific fact is information that can be independently verified by any trained person—for example, the fact that an iron deficiency leads to anemia. A law of nature is a generalization about the predictable ways in which matter and energy behave. It is the result of inductive reasoning based on repeated, confirmed observations. Some laws are expressed as concise verbal statements, such as the law of complementary base pairing: In the double helix of DNA, a chemical base called adenine always pairs with one called thymine, and a base called guanine always pairs with cytosine (see p. 117). Other laws are expressed as mathematical formulae, such as Boyle’s law, used in respiratory physiology: Under specified conditions, the volume of a gas (V) is inversely proportional to its pressure (P)—that is, V ∝ 1/P. A theory is an explanatory statement or set of statements derived from facts, laws, and confirmed hypotheses. Some theories have names, such as the cell theory, the fluidmosaic theory of cell membranes, and the sliding filament sal78259_ch01_001-027.indd 9 Major Themes of Anatomy and Physiology 9 theory of muscle contraction. Most, however, remain unnamed. The purpose of a theory is not only to concisely summarize what we already know but, moreover, to suggest directions for further study and to help predict what the findings should be if the theory is correct. Law and theory mean something different in science than they do to most people. In common usage, a law is a rule created and enforced by people; we must obey it or risk a penalty. A law of nature, however, is a description; laws do not govern the universe, they describe it. Laypeople tend to use the word theory for what a scientist would call a hypothesis—for example, “I have a theory why my car won’t start.” The difference in meaning causes significant confusion when it leads people to think that a scientific theory (such as the theory of evolution) is merely a guess or conjecture, instead of recognizing it as a summary of conclusions drawn from a large body of observed facts. The concepts of gravity and electrons are theories, too, but this does not mean they are merely speculations. Apply What You Know Was the cell theory proposed by Schleiden and Schwann more a product of the hypothetico–deductive method or of the inductive method? Explain your answer. Before You Go On Answer the following questions to test your understanding of the preceding section: 6. Describe the general process involved in the inductive method. 7. Describe some sources of potential bias in biomedical research. What are some ways of minimizing such bias? 8. Is there more information in an individual scientific fact or in a theory? Explain. 1.4 Human Origins and Adaptations Expected Learning Outcomes When you have completed this section, you should be able to a. explain why evolution is relevant to understanding human form and function; b. define evolution and natural selection; c. describe some human characteristics that can be attributed to the tree-dwelling habits of earlier primates; and d. describe some human characteristics that evolved later in connection with upright walking. If any two theories have the broadest implications for understanding the human body, they are probably the cell theory and the theory of natural selection. Natural selection, 11/2/10 9:06 AM
  • 10 PART ONE Organization of the Body an explanation of how species originate and change through time, was the brainchild of Charles Darwin (1809–82)—probably the most influential biologist who ever lived. His book, On the Origin of Species by Means of Natural Selection (1859), has been called “the book that shook the world.” In presenting the first well-supported theory of evolution, On the Origin of Species not only caused the restructuring of all of biology but also profoundly changed the prevailing view of our origin, nature, and place in the universe. On the Origin of Species scarcely touched upon human biology, but its unmistakable implications for humans created an intense storm of controversy that continues even today. In The Descent of Man (1871), Darwin directly addressed the issue of human evolution and emphasized features of anatomy and behavior that reveal our relationship to other animals. No understanding of human form and function is complete without an understanding of our evolutionary history. Evolution, Selection, and Adaptation Evolution simply means change in the genetic composition of a population of organisms. Examples include the evolution of bacterial resistance to antibiotics, the appearance of new strains of the AIDS virus, and the emergence of new species of organisms. Natural selection is the principal theory of how evolution works. It states essentially this: Some individuals within a species have hereditary advantages over their competitors—for example, better camouflage, disease resistance, or ability to attract mates—that enable them to produce more offspring. They pass these advantages on to their offspring, and such characteristics therefore become more and more common in successive generations. This brings about the genetic change in a population that constitutes evolution. Natural forces that promote the reproductive success of some individuals more than others are called selection pressures. They include such things as climate, predators, disease, competition, and the availability of food. Adaptations are features of an organism’s anatomy, physiology, and behavior that have evolved in response to these selection pressures and enable the organism to cope with the challenges of its environment. We will consider shortly some selection pressures and adaptations that were important to human evolution and make the human body what it is today. Darwin could scarcely have predicted the overwhelming mass of genetic, molecular, fossil, and other evidence of human evolution that would accumulate in the twentieth century and further substantiate his theory. A technique called DNA hybridization, for example, suggests a difference of only 1.6% in DNA structure between humans and chimpanzees. Chimpanzees and gorillas differ by 2.3%. DNA structure suggests that a chimpanzee’s sal78259_ch01_001-027.indd 10 DEEPER INSIGHT 1.1 Evolutionary Medicine Vestiges of Human Evolution One of the classic lines of evidence for evolution, debated even before Darwin was born, is vestigial organs. These structures are the remnants of organs that apparently were better developed and more functional in the anc