Essentials of Human Anatomy and Physiology, 12th edition (2018) - Elaine N. Marieb

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Brief Contents 1  The Human Body: An Orientation 1 10  Blood 337 2  Basic Chemistry 24 11 The Cardiovascular System 356 3  Cells and Tissue 62 12 The Lymphatic System and Body Defenses 398 4 Skin and Body Membranes 109 13 The Respiratory System 436 5  The Skeletal System 134 14 The Digestive System and Body 6  The Muscular System 181 Metabolism 463 7  The Nervous System 225 15 The Urinary System 511 8  Special Senses 278 16 The Reproductive System 538 9 The Endocrine System 308 Word Roots, Prefixes, and Suffixes by Chapter More root words appear in Appendix B on page 584. Chapter 1: The Human Body: Chapter 11: The Cardiovascular procto- rectum, anus An Orientation System vestibul- vestibule caput-, cephal- head angi- vessel Chapter 15: The Urinary System cervic-, cervix neck aort- great artery adren- toward the kidney dors- the back cardi-, cardio- heart cyst- sac, bladder venter, ventr- abdomen hema-, hemato-, hemo- blood diure-, mictur- urinate phleb- vein nephro-, ren- kidney Chapter 3: Cells and Tissues thromb- clot cutic-, derm- skin Chapter 16: The Reproductive cyt- cell Chapter 13: The Respiratory System lip-, lipo- fat, lipid System cervic-, cervix neck (i.e. of uterus) medull-, myelo- marrow aero- air hyster-, hystero- uterus, womb myo- muscle broncho- bronchus (pl. bronchi) orchid- testis osteo- bone pleur- side, rib ov-, ovi- egg pneumo- air, wind peri- around Chapter 5: The Skeletal System pulmo- lung vagin- a sheath append- hang to rhin-, rhino- nose vulv- a covering ax-, axi-, axo- axis, axle Chapter 14: The Digestive Miscellaneous Chapter 7: The Nervous System System and Body Metabolism gene- beginning, origin cerebro-, enceph- brain bucco- cheek kin-, kines- move neuro- nerve chole- bile lymph- water oculo-, ophthalmo- eye entero-, ile- intestine oligo- few oto- ear eso- within esophagus phobia- fear psycho- mind gastr- stomach photo- light glosso-, lingua- tongue pyo- pus hepat- liver roentgen X-ray labi-, labri- lip odonto- teeth Learn the Essential What, How & Why of Human Anatomy & Physiology With the Twelfth Edition of Essentials of Human Anatomy & Physiology, science educator Suzanne Keller joins bestselling author Elaine Marieb in helping learners focus on the What, How & Why of A&P, without getting sidetracked in details. NEW! What, How & Why chapter previews introduce key examples of anatomy and physiology concepts that will be covered in the chapter. This technique helps learners hone in on what they are studying, how it functions, and why it is important for them to learn. NEW! Building Vocabulary Coaching Activities in MasteringA&P help students learn the essential language of A&P. See p. 356. Focus on Essential A&P Concepts Throughout every chapter, the text’s conversational writing style and straightforward explanations have been strengthened with familiar analogies and abundant mnemonic cues to help students learn and remember concepts. UPDATED! Exceptionally clear photos and illustrations, including dozens of new and improved figures, present concepts and processes at the right level of detail. Many figures from the text are assignable as Art-­ Labeling Activities in MasteringA&P. See p. 111. Unique Concept Links reinforce previously-learned concepts and help students make connec­ tions across body systems while learning new material. See p. 256. Explore Essential Careers and Clinical Examples To inspire and inform students who are preparing for future healthcare careers, up-to-date clinical applications are integrated in context with discussions about the human body. UPDATED! Homeostatic Imbalance discussions are clinical examples that revisit the text’s unique theme by describing how the loss of homeostasis leads to pathology or disease. Related assessment questions are assignable in MasteringA&P, along with Clinical Case Study coaching activities. See p. 269. Focus on Careers essays feature conversations with working professionals and explain the relevance of anatomy and physiology course topics across a wide range of allied health careers. Featured careers include: Ch. 2 Pharmacy Technician Ch. 4 Medical Transcriptionist Ch. 5 Radiologic Technologist Ch. 8 Physical Therapy Assistant Ch. 10 Phlebotomy Technician Ch. 15 Licensed Practical Nurse Students can visit the MasteringA&P Study Area for more information about career options that are relevant to studying anatomy and physiology. See p. 56. Continuous Learning Before, During, and After Class MasteringA&P improves results by engaging students before, during, and after class. Before Class Dynamic Study Modules enable students to study more effectively on their own. With the Dynamic Study Modules mobile app, students can quickly access and learn the concepts they need to be more successful on quizzes and exams. NEW! Instructors can now select which questions to assign to students within each module. Instructors can further encourage students to prepare for class by assigning NEW! Building Vocabulary activities, reading questions, art labeling activities, and more. with MasteringA&P During Class NEW! Learning Catalytics is a “bring your own device” (laptop, smartphone, or tablet) engagement, assessment, and classroom intelligence system. Students use their device to respond to open-ended questions and then discuss answers in groups based on their responses. Visit learningcatalytics.com to learn more. After Class A wide variety of interactive coaching activities can be assigned to students as homework, including Art-Labeling Activities, Interactive Physiology 2.0 tutorials, Clinical Case Studies, and activities featuring A&P Flix 3-D movie- quality animations of key physiological processes. A&P concepts come to life with MasteringA&P Media references in the text direct learners to digital resources in the MasteringA&P Study Area, including practice tests and quizzes, flashcards, a complete glossary, and more. NEW! Interactive Physiology 2.0 NEW! Interactive Physiology 2.0 helps students advance beyond memorization to a genuine understanding of complex physiological processes. Fun, interactive tutorials, games, and quizzes give students additional explanations to help them grasp difficult concepts. IP 2.0 features brand-new graphics, quicker navigation, and more robust interactivity. Practice Anatomy Lab (PAL™ 3.0) is a virtual anatomy study and practice tool that gives students 24/7 access to the most widely used lab specimens, including the human cadaver, anatomical models, histology, cat, and fetal pig. PAL 3.0 is easy to use and includes built-in audio pronunciations, rotatable bones, and simulated fill-in-the- blank lab practical exams. Access the complete textbook on and offline with eText 2.0 NEW! The Twelfth Edition is available in Pearson’s fully-accessible eText 2.0 platform.* NEW! The eText 2.0 mobile app offers offline access and can be downloaded for most iOS and Android phones and tablets from the iTunes or Google Play stores. Powerful interactive and customization functions include instructor and student note-taking, highlighting, bookmarking, search, and links to glossary terms. *The eText 2.0 edition will be live for Fall 2017 classes. Additional Support for Students and Instructors NEW! Anatomy & Physiology Coloring Workbook Twelfth Edition by Elaine N. Marieb and Simone Brito The perfect companion to Essentials of Human Anatomy & Physiology, this engaging interactive workbook helps students get the most out of their study time. The Twelfth Edition includes NEW! crossword puzzles for every chapter, along with coloring activities, self-assessments, “At the Clinic” questions, and unique “Incredible Journey” visualization exercises that guide learners into memorable explorations of anatomical structures and physiological functions. NEW! IN FULL COLOR! Essentials of Human Anatomy & Physiology Laboratory Manual Seventh Edition by Elaine N. Marieb and Pamela B. Jackson This popular lab manual provides 27 exercises for a wide range of hands-on laboratory experiences, designed especially for a short A&P Lab course. This edition, which includes a Histology Atlas with 55 photomicrographs, features NEW! full-color illustrations, photos, and page design that help students navigate and learn the material faster and easier than ever before. Each concise lab exercise includes a Pre-Lab Quiz, brief background information, integrated learning objectives, student-friendly review sheets, and more. The Instructor Resources Area in MasteringA&P includes the following downloadable tools: • All of the figures, photos, and tables from the text in JPEG and PowerPoint® formats, in labelled and unlabeled versions, and with customizable labels and leader lines • Step-edit Powerpoint slides that present multi-step process figures step-by-step • Clicker Questions and Quiz Show Game questions that encourage class interaction • A&PFlix™ animations bring human anatomy and physiology concepts to life • Customizable PowerPoint® lecture outlines save valuable class prep time • A comprehensive Instructor’s Guide includes lecture outlines, classroom activities, and teaching demonstrations for each chapter. • Test Bank provides a wide variety of customizable questions across Bloom’s taxonomy levels. Includes art labeling questions, and available in Microsoft® Word and TestGen® formats. TWELFTH EDITION ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY ELAINE N. MARIEB, R.N., Ph.D., HOLYOKE COMMUNITY COLLEGE SUZANNE M. KELLER, Ph.D., INDIAN HILLS COMMUNITY COLLEGE 330 Hudson Street, NY NY 10013 Editor-in Chief: Serina Beauparlant Proofreader: Betsy Dietrich Senior Courseware Portfolio Manager: Lauren Harp Compositor: iEnergizer Aptara®, Ltd. Content and Design Manager: Michele Mangelli, Mangelli Art and Production Coordinator: David Novak Productions, LLC Indexer: Steele/Katigbak Managing Producer: Nancy Tabor Interior Designer: tani hasegawa and Hespenheide Desgin Courseware Director, Content Development: Barbara Yien Cover Designer: Hespenheide Desgin Courseware Sr. Analysts: Suzanne Olivier and Alice Fugate Illustrators: Imagineering STA Media Services, Inc. Courseware Specialist: Laura Southworth Rights & Permissions Manager: Ben Ferrini Editorial Coordinator: Nicky Montalvo Photo Researcher: Kristin Piljay Mastering Content Developer: Cheryl Chi Manufacturing Buyer: Stacey Weinberger Director of Mastering Production: Katie Foley Executive Marketing Manager: Allison Rona Associate Producer, Science: Kristen Sanchez Rich Media Content Producer: Ziki Dekel Cover Photo Credit: Ben Welsh/Getty Images Copyeditor: Sally Peyrefitte Copyright © 2018, 2015, 2012 Pearson Education, Inc. All Rights Reserved. Printed in the United States of America. This publication is protected by copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise. For information regarding permissions, request forms and the appropriate contacts within the Pearson Education Global Rights & Permissions department, please visit www.pearsoned.com/permissions/. Acknowledgements of third party content appear on page 604, which constitutes an extension of this copyright page. PEARSON, ALWAYS LEARNING, MasteringA&P, A&P Flix, and PAL, are exclusive trademarks in the U.S. and/or other countries owned by Pearson Education, Inc. or its affiliates. Unless otherwise indicated herein, any third-party trademarks that may appear in this work are the property of their respective owners and any references to third-party trademarks, logos or other trade dress are for demonstrative or descriptive purposes only. Such references are not intended to imply any sponsorship, endorsement, authorization, or promotion of Pearson’s products by the owners of such marks, or any relationship between the owner and Pearson Education, Inc. or its affiliates, authors, licensees or distributors. Library of Congress Cataloging-in-Publication Data Names: Marieb, Elaine Nicpon | Keller, Suzanne M. Title: Essentials of human anatomy & physiology. Other titles: Essentials of human anatomy and physiology Description: Twelfth edition / Elaine N. Marieb, R.N., Ph.D., Holyoke Community College, Suzanne M. Keller, Ph.D., Indian Hills Community College. | Boston : Pearson, 2016. | Includes index. Identifiers: LCCN 2016039812| ISBN 9780134395326 | ISBN 0134395328 Subjects: LCSH: Human physiology. | Human anatomy. Classification: LCC QP34.5 .M455 2016 | DDC 612--dc23 LC record available at https://lccn.loc.gov/2016039812 ISBN 10: 0-13-439532-8 (Student edition) ISBN 13: 978-0-13-439532-6 (Student edition) ISBN 10: 0-13-464954-0 (Instructor’s Review Copy) ISBN 13: 978-0-13-464954-2 (Instructor’s Review Copy) 5 4 3 2 1 16 17 18 19 20 About the Authors dumperina Elaine Marieb After receiving her Ph.D. in Suzanne Keller Suzanne M. Keller began zoology from the University of Massachusetts at her teaching career while she was still in graduate Amherst, Elaine N. Marieb joined the faculty of the school at the University of Texas Health Science Biological Science Division of Holyoke Community Center in San Antonio, Texas. Inspired by her life- College. While teaching at Holyoke Community long passion for learning, Dr. Keller quickly College, where many of her students were pursu- adopted a teaching style focused on translating ing nursing degrees, she developed a desire to bet- challenging concepts into easily understood parts ter understand the relationship between the using analogies and stories from her own experi- scientific study of the human body and the clinical ences. An Iowa native, Dr. Keller uses her expertise aspects of the nursing practice. To that end, while to teach microbiology and anatomy and physiol- continuing to teach full time, Dr. Marieb pursued ogy at Indian Hills Community College, where her nursing education, which culminated in a most of her students are studying nursing or other ­Master of Science degree with a clinical specializa- health science ­programs. tion in gerontology from the University of Massa- Dr. Keller values education as a way for students chusetts. It is this experience that has informed the to express their values through the careers they development of the unique perspective and acces- pursue. She supports those endeavors both in and sibility for which her publications are known. out of the classroom by participating in her local Dr. Marieb has given generously to provide oppor- Lions Club, by donating money to the Indian Hills tunities for students to further their education. She Foundation to fund scholarships, and by financially funds the E. N. Marieb Science Research Awards at supporting service-learning trips for students. Dr. Mount Holyoke College, which promotes research by Keller also enjoys sponsoring children in need with undergraduate science majors, and has underwritten gifts for the holidays. renovation of the biology labs in Clapp Laboratory at Dr. Keller is a member of the Human Anatomy that college. Dr. Marieb also contributes to the Univer- and Physiology Society (HAPS) and the Iowa Acad- sity of Massachusetts at Amherst, where she gener- emy of Science. Additionally, while engaged as an ously provided funding for reconstruction and author, Dr. Keller has served on multiple advisory instrumentation of a cutting-edge cytology research boards for various projects at Pearson and has laboratory. Recognizing the severe national shortage authored assignments for the MasteringA&P online of nursing faculty, she underwrites the Nursing Schol- program. When not teaching or writing, Dr. Keller ars of the Future Grant Program at the university. In enjoys reading, trav­eling, family gatherings, and January 2012, Florida Gulf Coast University named a relaxing at home under the watchful eyes of her new health professions facility in her honor. The Dr. two canine children. Elaine Nicpon Marieb Hall houses several ­specialized laboratories for the School of Nursing, made possible by Dr. Marieb’s generous support. iii New to the Twelfth Edition This edition has been thoroughly updated. New “What, How, Why” art opens each chapter, highlighting key concepts relating to the chapter topic. Other specific chapter-by-chapter changes include the following: Chapter 1: The Human Body: An Orientation • New colors used in Figure 3.14 DNA images to help students track • Updated description of the integumentary system to include new and old strands of DNA. vitamin D production in the presence of sunlight. • New description of each chromosome being composed of two • Updated definition of the term crural to specify the anterior leg, sister chromatids. or shin. • New explanation of protein synthesis includes the role of the large • New “Critical Thinking and Clinical Application” question on blood ribosomal subunit in peptide bond formation. clotting and feedback regulation. • New Figure 3.18 descriptions of nuclei lining up in simple • New “Critical Thinking and Clinical Application” question on using columnar and not lining up in pseudostratified epithelia. anatomical language to describe the location of a spinal injury and • New description of cell shapes in different layers of stratified identifying the best medical imaging technique to diagnose a epithelia as “squished” and variable. spinal problem. • New analogy for mucus produced by goblet cells as a “sticky trap” • Updated “A Closer Look: Medical Imaging” with new discussion for dust and debris. and images of mammogram and bone densitometry. • New Figure 3.19 labels for osteocytes, the elastic and collagen • New “Did You Get It?” questions throughout the chapter. fibers in areolar connective tissue, and the fluid matrix of blood; new art for dense fibrous connective tissue. Chapter 2: Basic Chemistry • New analogy for reticular tissue as “cellular bleachers” where other • New example of atomic symbol and Latin derivative for potassium. cells rest to monitor the body. • Revised discussion of hydrogen bonds to clarify that electrons are • Updated Figure 3.21 to include the term neuroglia to describe not involved in this type of bond as they are in covalent and ionic supporting cells. bonds. • New information added to Figure 3.22: cartilage added to the • New example of importance of hydrogen bond in holding DNA connective tissue list and two major hallmarks of each of the four strands together. tissue types. • All references to hydroxyl ion have been corrected to hydroxide ion. • New example of atrophy: when a broken leg is in a cast, lack of • New sports analogies for acids and bases: putting electrons “in the use causes muscles to atrophy during healing. game,” to represent free protons versus taking electrons “out of the • Revised “A Closer Look: Cancer—An Intimate Enemy” and updated art. game,” to represent binding a proton so it cannot contribute to a • New “Short Answer Essay” questions on the components of the shift in pH. plasma membrane and their functions and on contrasting • New “Did You Get It?” question part on the difference in pH cytokinesis, interphase, and mitosis. between solutions at pH 11 and pH 5. • New “Critical Thinking and Clinical Application” question on IV • Introduced concepts of hydrophilic and hydrophobic in discussion fluids and tonicity. of phospholipids to help explain the functions of the polar head • New “Did You Get It?” questions throughout the chapter. and fatty acid tails in cell membranes. • Updated “Did You Get It?” question on lipids to include both Chapter 4: Skin and Body Membranes phospholipids and cholesterol as cell membrane components. • New Figure 4.1 on epithelial membranes. • New analogy comparing the alpha (α)-helix to a metal spring. • New description of sensory receptors as part of nervous system • New analogy comparing a beta (β)-sheet to a pleated skirt, or including a list of the stimuli detected. paper folded into a fan. • New text updates on Figure 4.4 on epidermal structure; included a • New analogy comparing enzymes and substrates to scissors and new figure question on stratum lucidum. paper, respectively. • New analogy for epidermal dendritic cells as “sentries” guarding • New description of RNA function as DNA’s “molecular assistant.” the skin. • New shorthand symbols for messenger (mRNA), transfer (tRNA) • New photo of stage 2 decubitus ulcer added to Homeostatic and ribosomal (rRNA) added. Imbalance 4.2. • New analogy comparing glucose and ATP to crude oil and gasoline; • New layout for Figure 4.7 combining scanning electron micrograph energy must be in the proper form before it can be used by cells. of hair shaft with existing art of the hair root and follicle. • New explanation of why the terminal phosphate bonds in ATP are • New discussion of fourth-degree burns. high energy. • New criteria for determining whether a burn is critical, including • New “Critical Thinking and Clinical Application” question on sickle circumferential burns, burns of the airway, and burns to the genital cell anemia. area. • New images of basal cell and squamous cell carcinoma in Chapter 3: Cells and Tissues Figure 4.11. • New description of the principle of complementarity. • New component added to ABCDE rule: now includes “Evolution,” • New information about how mitochondria divide. changes in a skin lesion over time. • New “cargo” in the form of a membrane-bound receptor protein • New “Short Answer Essay” questions on the risks of full-thickness added to pathway 2 of Figure 3.6. burns, contrasting eccrine and apocrine sweat glands, and the • New analogy for lysosomes as “cellular stomachs.” relative severity of different skin infections. • New art of plasma membrane and new detail of mitochondrial • New “Critical Thinking and Clinical Application” question on burns. function including aerobic respiration in Table 3.1. • New “Did You Get It?” questions throughout the chapter. • New analogy of dust “crowd surfing” on the mucus that cilia carry from the lungs. Chapter 5: The Skeletal System • New description of neuron function includes production of • Updated description of long bones. neurotransmitters. • New analogy comparing lubrication over articular cartilage at joints to a slick marble floor. iv New to the Twelfth Edition v • Updated descriptions of red and yellow bone marrow. • Updated description of Nissl body function. • Updated descriptions of sagittal and coronal sutures. • New description clarifying the difference between a synapse and • Updated description of the capitulum of the humerus. synaptic cleft. • New analogy comparing the trochlea meeting the trochlear notch • New analogy for a myelin sheath as the wrapping on an electrical to a curved “tongue-in-groove” joint. cord. • Updated description of buttock injections to include the • New explanation clarifying the differences between myelin sheaths consequences of hitting a nerve. in the CNS and PNS. • Updated description of a synovial membrane to include areolar • New explanation clarifying the “short circuit” event in multiple connective tissue. sclerosis means that the signal may stop or “jump” to an • Updated description of cartilaginous joints. unmyelinated neuron. • New description of saddle joints including a reference to • New analogy for the structure of a unipolar cell body as a “cul-de- opposable thumbs. sac” off the “main road” that is the axon. • Updated list of triggers for rheumatoid arthritis. • Replaced references to the term basal ganglia with the more • Discussion of the fetal skull and fontanels moved to the accurate term basal nuclei. Developmental Aspects section. • Replaced the term arachnoid villi with arachnoid granulations. • New analogy likening skulls of small children to “bobble heads.” • New statistics on stroke as the fifth leading cause of death in the • Updated review question on bones that articulate with the United States (formerly identified as the third leading cause). sphenoid to reflect only bones shown in the figures of Chapter 5. • New statistics regarding the rate of survival after a stroke. • Updated “Short Answer Essay” question on synovial joints to • Replaced the phrase “mentally retarded” in the discussion of include osteoarthritis. cerebral palsy with “intellectually disabled.” • New “Short Answer Essay” question contrasting the foramen • New information included in “A Closer Look: The ‘Terrible Three’” magnum and obturator foramen. reflecting the role of calcium in apoptosis, two new drugs for • New “Critical Thinking and Clinical Application” question on gouty treatment of Parkinson’s disease, and the variation in dopamine arthritis. levels in patients with Huntington’s disease. • New statistics, information, and images added to “A Closer Look: • New information incorporated in “A Closer Look: Tracking Down Joint Ventures.” CNS Problems” to include a new dopamine imaging technique • Updated description of comminuted fractures on Table 5.2. called DaTscan. • Updated Figure 5.6 to include osteoblasts and osteoclasts in the descriptions of bone addition and resorption, respectively. Chapter 8: Special Senses • Updated Systems In Sync with respect to the descriptions of • New description of lacrimal caruncle. relationships of cardiovascular and muscular systems to the • New description of optic disc and the resulting blind spot. skeletal system. • New analogy comparing the ability to see intermediate colors (between the red, green, and blue cones) to mixing paint. Chapter 6: The Muscular System • Updated the description of cataracts. • Updated descriptions of tendons and aponeuroses. • New example of motion detected by dynamic equilibrium: a • New analogy about running to explain the difference between the spinning carnival ride. contraction of skeletal muscle (fast) versus smooth muscle (slow). • New analogy for bending of the cupula as divers’ fins in water. • Updated description of a sarcomere to include its role as the • New description of foliate papillae on the side of the tongue, structural and functional unit of muscle. another location for taste buds. • Added discussion of titin to the description of a sarcomere as the • New art showing the retina in Figure 8.5. elastic filament that attaches myosin to the Z disc. • New Figure 8.6 showing the graph of rods and cones, and which • New Homeostatic Imbalance on ALS (amyotropic lateral sclerosis, wavelengths of light are detected by each. or Lou Gehrig’s disease). • Updated Figure 8.12b on maculae. • New “Did You Get It?” question on the roles of calcium in muscle • New “Did You Get It?” questions throughout the chapter. contraction. • Updated descriptions of cross-bridge formation and the sliding Chapter 9: The Endocrine System filament theory, including the role of ATP. • Updated discussion of the mechanism of hormone action, • New link to IP Essentials for the sliding filament theory. including Figure 9.1 and its caption, to reflect that steroid • New description of flaccid versus spastic paralysis. hormones can act via either second messenger or direct gene • New mnemonic device for adduction: “add” back to the body by activation. moving toward the trunk (midline). • Updated explanation of how hormones alter cell activity. • New descriptions of dorsiflexion and plantar flexion with respect • New analogy comparing second-messenger systems to delivering a to the head: toes point toward the head or away, respectively. letter. • New girdle analogy for abdominal wall muscles “holding guts in.” • Revised coverage of endocrine glands to reflect their location in • New description of the consequences of an injection being too body from superior to inferior; Table 9.1 has also been revised to close to, or hitting, the sciatic nerve. reflect the new order. • New description of tailor’s muscle sitting position. • Updated description explaining why a goiter forms in the absence • New description of myasthenia gravis as an autoimmune disease. of iodine. • New “Short Answer Essay” question about the relationship • Updated description of body proportions in cretinism. between wrist flexors and extensors, including their locations. • New “Did You Get It?” question on adrenal cortex hormones. • New figure question for Figure 6.20 on the origin(s) and insertion(s) of the rectus femoris depending on the action being Chapter 10: Blood performed. • Updated explanation of why the normal temperature of blood is a • Updated explanation of steps in Figure 6.5. bit higher than body temperature. • Added definitions for the suffixes -cytosis and -penia. Chapter 7: The Nervous System • Updated the analogy comparing the shape of the eosinophil • Updated Figure 7.13 to use superior and inferior instead of nucleus to earmuffs. cephalad and caudal. • Updated the role of monocytes to include activation of • Updated Figure 7.24 to clarify why there are eight cervical nerves lymphocytes. but only seven cervical vertebrae. • Updated the list of locations where red marrow is found in adults. • New Learning Outcome on the structures and functions of neurons • Updated the major anticoagulants to include warfarin. and neuroglia. • New description of petechiae includes comparison to a skin rash. vi New to the Twelfth Edition • Added a learning tool about blood type reminding readers that a • Updated Table 12.1 regarding the role of nasal hairs to include person does not make antibodies against their own blood type filtration of airborne particles. antigen(s). • Updated Table 12.3 entry for “Cytokines: Perforin and granzymes” • Updated discussion of lack of vitamin B12 as the cause of to include natural killer (NK) cells. pernicious anemia and how this relates to intrinsic factor. • New “Did You Get It?” questions throughout the chapter. Chapter 11: The Cardiovascular System Chapter 13: The Respiratory System • Updated description of pericardium. • New information explaining neural regulation of breathing with • Revised discussion of the function of the atria to clarify that they respect to the dorsal and ventral respiratory groups of the medulla. assist with ventricular filling. • New Short Answer Essay question contrasting hyperventilation and • Arteries and veins are now introduced in terms of the direction of hyperpnea. blood flow with respect to the heart. • Updated “A Closer Look” on cleanliness and asthma. • New analogy comparing valve cusps filling with blood to a • New “Did You Get It?” questions throughout the chapter. parachute filling with air. • New analogy comparing the intrinsic conduction system setting Chapter 14: The Digestive System heart rhythm to a drummer setting the beat for a rock band • New illustration outlining the parietal and visceral layers of the playing a song. peritoneum (Figure 14.5). • New discussion of AEDs (automatic external defibrillators) • New illustrations showing both deciduous and permanent teeth in included in the discussion of fibrillation. greater detail (Figure 14.9). • Reorganized section on the cardiac cycle to include five stages. • Updated description of circular folds to provide students with a • New “Did You Get It?” question about isovolumetric contraction. visual image of a corkscrew that slows progression of food and • Updated description of the effect of congestive heart failure on increases surface area at the same time. stroke volume. • Added detail that rennin in infants is the same enzyme used to • Updated description of pulmonary congestion. curdle milk in cheesemaking. • Updated description of pulmonary embolism. • Added narcotic pain medications to the list of causes of • Discussion of fetal circulation moved to the Developmental constipation, with stool softeners as a method of treatment. Aspects section. • New “Did You Get It?” question on the four types of teeth and • Updated description of the blood pressure gradient to include a their functions. pressure of zero in the right atrium. • Added brief discussion of nucleic acid digestion, including the • New layout of Figure 11.8 reflecting five stages of the cardiac cycle. source of the enzymes and the reminder that nucleotides are the • Updated Figure 11.9 description to clarify that any change in heart building blocks. rate or stroke volume will also cause a change in cardiac output. • Revised “A Closer Look” box on obesity to update references, • Updated description of Figures 11.13 and 11.14 to include a statistics, and methods used to determine body composition, such statement that all vessels are bilateral unless otherwise stated in as DEXA, the Bod Pod, and underwater weighing. the text. • Updated “A Closer Look” box on atherosclerosis. Chapter 15: The Urinary System • Updated descriptions of the arterioles that connect to the Chapter 12: The Lymphatic System and Body Defenses glomerulus. • Updated Figure 12.10 on lysis by complement to reflect water • Included a new learning tool describing the internal urethral flowing into the cell to cause lysis. sphincter as involuntary. • Added the role of B cells in antigen presentation to Figure 12.19. • New “Short Answer Essay” question contrasting the homeostatic • New information added regarding discovery of lymphatics in the imbalances oliguria, anuria, polyuria, and nocturia. central nervous system. • New “Critical Thinking and Clinical Application” question about • Updated the description of adaptive defenses as defenses that fight the relationship between hypertension and impaired kidney antigens that get past the innate defenses. function, and tests that are used for determining impaired kidney • New description of how natural killer cells kill: via perforin and function. granzymes. • New information included in “A Closer Look: Renal Failure and the • Updated the description of positive chemotaxis to include Artificial Kidney” about a blood test to determine the creatinine movement toward the stimulus. level in order to estimate the rate of glomerular filtration. • Revised description of interferon to clarify that interferon fights • Did You Get It? only viral pathogens, not bacteria or fungi. • New antibody function has been listed: opsonization. Chapter 16: The Reproductive System • New description of Graves’ disease explaining that excess • New explanation of the purpose of polar bodies: to reduce the production of thyroxine is in response to antibodies that mimic chromosome number during oogenesis. TSH (thyroid-stimulating hormone). • Update of suggested age range for women to begin having regular • New descriptions of two additional types of hypersensitivities: mammograms: between 45 and 54. reactions resulting in cell lysis and those forming antigen-antibody • New Concept Link on chemotaxis. complexes. • New photomicrograph showing sperm swarming an oocyte in • New example of when epinephrine is used during acute Figure 16.16. hypersensitivity: EpiPen® injection. • New explanation of how an egg blocks additional sperm from • New Short Answer Essay question provided on mechanisms of entering; the surface sperm receptors on an oocyte are shed after killing used by the immune system, including lysozyme, perforin, the first sperm enters the cell. and granzymes, and membrane attack complex (MAC). • New clarification with updated definitions of miscarriage and • Updated “A Closer Look” box on AIDS, including new title. abortion. Acknowledgments Many people contributed to our efforts in the cre- University; Amy Goode, Illinois Central College; ation of this twelfth edition. We offer our profound Jeannette Hafey, Springfield College; Ashley Hagler, thanks to the following reviewers, whose thought- Gaston College; Frances Miles, Lake Michigan ful critiques informed and enhanced our develop- ­College–Napier Avenue Campus; Margaret Ott, Tyler ment of this edition: Junior College; Heidi Peterson, Indian Hills Commu- • William Brazelle, University of South Florida nity College–Ottumwa Campus; Laura Ritt, Burling- ton County College; Holly Sanders, Gwinnett • Sheree Daniel, Trinity Valley Community Technical College; Leba Sarkis, Aims Community College College; Gustavo A. Solis, Forsyth Technical Com- • Trevor Day, Mount Royal University munity College; Ginny Stokes, Nash Community • Camille Di Scala, Chandler-Gilbert Community College; Robert Suddith, Cape Fear Community Col- College lege; John F. Tarpey, City College of San Francisco; • Pamela Boyter Jackson, Piedmont Technical Deborah S. Temperly, Delta College; Claudia Wil- College liams, Campbell University. • Roop Jayaraman, Central Michigan University The entire group from Pearson and beyond deserves our heartfelt thanks for being the best • Kimberly Kushner, Pueblo Community College team around! They have provided support, guid- • Frances Mills, Lake Michigan College ance, and humor throughout the writing process, • Diane Pelletier, Green River Community which made the process fun and was most appre- College ciated. Special thanks to Serina Beauparlant, Edi- • Heidi Peterson, Indian Hills Community tor-In-Chief, Brooke Suchomel, Sr. Acquisitions College Editor, and Tiffany Mok, Program Manager who passed the reins to Lauren Harp, Sr. Portfolio Man- • Kenneth Ryan, Alexandria Technical and ager, for crossing the finish line. Thanks also to Community College Nicky Montalvo, Editorial Coordinator. Thank you • Holly Sanders, Gwinnett Technical College to the content development team—Suzanne Olivier, • Scott Schaeffer, Harford Community College Alice Fugate, and Laura Southworth—for their • I-Chia Shih, Leeward Community College, attention to detail and collaborative minds. Thank University of Hawaii you Patrice Fabel, Ziki Dekel, and Lauren Hill for supervising an impressive variety of media content • K. Dale Smoak, Piedmont Technical College that will benefit both students and instructors. A • Bill Snyder, Bluegrass Community and special thank-you to Gary Hespenheide for the Technical College book’s beautiful and creative new interior and • Greg Tefft, Northwest State Community College cover designs. The work of Kristin Piljay, Photo • Sandra Uyeshiro, Modesto Junior College Researcher, resulted in some striking new photos • Khursheed Wankadiya, Central Piedmont for this edition; and Sally Peyrefitte, our excellent Community College and diligent copyeditor, ensured a consistent style throughout the book. Proofreader Betsy Dietrich • Carol T. Wismer, College of Lake County skillfully reviewed every page proof, and Sallie Thanks are also extended to the reviewers of the Steele provided a thorough and accurate index. Eleventh Edition: Carmen Carpenter, South Univer- Our talented art house, Imagineering STA Media sity; Steven D. Collins, Niagara College; Janie Cor- Services, Inc., and compositor, Aptara, worked tire- bitt, Central Georgia Technical College–Milledgeville lessly to provide stunning artwork and student- Campus; Eric D. Forman, Sauk Valley Community friendly page layouts. Stacey Weinberger, Senior College; Andrew Goliszek, North Carolina A&T State Manufacturing Buyer, Allison Rona, and Derek vii viii Acknowledgments ­ errigo deserve special thanks for their expertise in P detail—David made the whole process smooth delivering and presenting the final product to the and successful. And last, but not least, Michele market. A special thank you goes to David Novak, Mangelli—a tremendous thank-you for your skillful our Production and Art Coordinator, for taking on oversight of all aspects of the 12th edition, includ- the role of two people during this edition and flaw- ing assisting a first-time co-author in all things pub- lessly handling every text and art-related production lishing . . . you’re an unflappable rock star! Elaine N. Marieb Suzanne M. Keller Anatomy and Physiology Pearson Education 1301 Sansome Street San Francisco, CA 94111 Contents 1  he Human Body: T Summary 21 Review Questions  22 An Orientation 1 Critical Thinking and Clinical Application Questions  23 An Overview of Anatomy and A Closer Look Medical Imaging: Physiology 1 Illuminating the Body 10 Anatomy 1 2 Physiology 2 Relationship between Anatomy Basic and Physiology 2 Chemistry 24 Levels of Structural Organization 2 From Atoms to Organisms 2 Concepts of Matter and Energy 24 Organ System Overview 3 Matter 24 Integumentary System • Skeletal System • Muscular Energy 25 System • Nervous System • Endocrine System Forms of Energy • Energy Form Conversions • Cardiovascular System • Lymphatic System • Respiratory System • Digestive System • Urinary System • Reproductive System Composition of Matter 26 Elements and Atoms 26 Maintaining Life 7 Atomic Structure 26 Necessary Life Functions 7 The Basic Atomic Subparticles • Planetary and Orbital Maintaining Boundaries • Movement • Responsiveness Models of an Atom • Digestion • Metabolism • Excretion • Reproduction Identifying Elements 28 • Growth Atomic Number • Atomic Mass Number • Atomic Survival Needs 9 Weight and Isotopes The Language of Anatomy 12 Molecules and Compounds 31 Anatomical Position 12 Chemical Bonds and Chemical Directional Terms 12 Reactions 32 Regional Terms 12 Bond Formation 32 Anterior Body Landmarks • Posterior Body Landmarks Role of Electrons • Types of Chemical Bonds Body Planes and Sections 15 Patterns of Chemical Reactions 36 Body Cavities 15 Synthesis Reactions • Decomposition Reactions Dorsal Body Cavity • Ventral Body Cavity • Other • Exchange Reactions • Factors Influencing the Rate Body Cavities of Chemical Reactions Homeostasis 19 Biochemistry: The Chemical Components of Homeostatic Control Composition of Living Matter 38 Systems 19 Inorganic Compounds 39 Feedback Mechanisms 19 Water • Salts • Acids and Bases ix x Contents Chapter 2, continued Classification of Epithelia 89 Simple Epithelia • Stratified Epithelia • Glandular Organic Compounds 42 Epithelium Carbohydrates • Lipids • Proteins • Nucleic Acids • Adenosine Triphosphate (ATP) Connective Tissue 93 Summary 57 Hallmarks of Connective Tissue 93 Review Questions  59 Extracellular Matrix 94 Critical Thinking and Clinical Types of Connective Tissue 94 Bone • Cartilage • Dense Connective Tissue • Loose Application Questions  61 Connective Tissue • Blood Focus on Careers Pharmacy Technician 56 Muscle Tissue 98 3 Skeletal Muscle 98 Cells Cardiac Muscle 98 and Tissues 62 Smooth Muscle 100 Nervous Tissue 100 Part I: Cells 62 Tissue Repair (Wound Healing) 100 Overview of the Cellular Basis Part III: Developmental of Life 62 Aspects of Cells and Anatomy of a Generalized Cell 63 Tissues 102 The Nucleus 63 Summary 104 Nuclear Envelope • Nucleolus • Chromatin The Plasma Membrane 64 Review Questions  107 The Fluid Mosaic Model • Cell Membrane Junctions Critical Thinking and Clinical The Cytoplasm 67 Application Questions  108 Cytosol and Inclusions • Organelles A Closer Look IV Therapy and Cellular Cell Extensions 71 “Tonics” 79 Cilia and Flagella • Microvilli A Closer Look Cancer—An Intimate Cell Diversity 74 Enemy 104 Cell Physiology 76 4 Membrane Transport 76 Passive Processes: Diffusion and Filtration Skin and Body Membranes 109 • Active Processes Cell Division 82 Preparations: DNA Replication • Events of Cell Division Protein Synthesis 85 Classification of Body Genes: The Blueprint for Protein Structure • The Role Membranes 109 of RNA • The Process of Protein Synthesis Epithelial Membranes 110 Part II: Body Tissues 88 Cutaneous Membrane • Mucous Membranes • Serous Membranes Epithelial Tissue 88 Connective Tissue Membranes 110 Hallmarks of Epithelium 88 Contents xi The Integumentary System (Skin) 112 Cervical Vertebrae • Thoracic Vertebrae • Lumbar Vertebrae • Sacrum • Coccyx Functions of the Integumentary System 112 Thoracic Cage 156 Structure of the Skin 113 Sternum • Ribs Epidermis • Dermis Skin Color 118 Appendicular Skeleton 158 Appendages of the Skin 119 Bones of the Shoulder Girdle 158 Cutaneous Glands • Hair and Hair Follicles • Nails Bones of the Upper Limbs 158 Homeostatic Imbalances of Skin 123 Arm • Forearm • Hand Infections and Allergies • Burns • Skin Cancer Bones of the Pelvic Girdle 162 Developmental Aspects of Skin and Body Bones of the Lower Limbs 164 Membranes 127 Thigh • Leg • Foot Summary 130 Joints 166 Review Questions  131 Fibrous Joints 169 Cartilaginous Joints 169 Critical Thinking and Clinical Application Questions  132 Synovial Joints 169 A Closer Look A Wrinkle Out of Types of Synovial Joints Based on Shape 170 Time 117 Developmental Aspects of the Focus on Careers Medical Skeleton 173 Transcriptionist 128 Birth to Adulthood 173 Systems in Sync 129 Older Adults 175 5 Summary 177 The Skeletal Review Questions  178 System 134 Critical Thinking and Clinical Application Questions  180 Focus on Careers Radiologic Bones: An Overview 134 Technologist 143 Functions of the Bones 135 A Closer Look Joint Ventures 166 Classification of Bones 135 Systems in Sync 176 Structure of Bone 137 Gross Anatomy of a Long Bone • Microscopic 6 Anatomy Bone Formation, Growth, and The Muscular Remodeling 141 Bone Formation and Growth • Bone Remodeling System 181 Bone Fractures 144 Overview of Muscle Tissues 181 Axial Skeleton 146 Muscle Types 181 Skull 146 Skeletal Muscle • Smooth Muscle • Cardiac Muscle Cranium • Facial Bones • The Hyoid Bone Muscle Functions 185 Vertebral Column (Spine) 152 Produce Movement • Maintain Posture and Body Position • Stabilize Joints • Generate Heat • Additional Functions xii Contents Chapter 6, continued A Closer Look Anabolic Steroids: Dying to Win? 205 Microscopic Anatomy of Skeletal Systems in Sync 220 Muscle 185 7 Skeletal Muscle Activity 187 Stimulation and Contraction of Single Skeletal The Nervous Muscle Fibers 187 The Nerve Stimulus and the Action Potential System 225 • Mechanism of Muscle Contraction: The Sliding Filament Theory Contraction of a Skeletal Muscle Organization of the Nervous as a Whole 191 System 226 Graded Responses • Providing Energy for Muscle Structural Classification 227 Contraction • Muscle Fatigue and Oxygen Deficit Functional Classification 227 • Types of Muscle Contractions—Isotonic and Isometric • Muscle Tone • Effect of Exercise on Muscles Nervous Tissue: Structure and Function 227 Muscle Movements, Roles, and Supporting Cells 227 Names 196 Neurons 229 Types of Body Movements 196 Anatomy • Classification • Physiology: Nerve Impulses Special Movements • Physiology: Reflexes Interactions of Skeletal Muscles in the Body 200 Central Nervous System 239 Naming Skeletal Muscles 202 Functional Anatomy of the Brain 239 Cerebral Hemispheres • Diencephalon • Brain Stem Arrangement of Fascicles 202 • Cerebellum Gross Anatomy of Skeletal Protection of the Central Nervous System 247 Meninges • Cerebrospinal Fluid • The Blood-Brain Muscles 203 Barrier Head and Neck Muscles 203 Brain Dysfunctions 251 Facial Muscles • Neck Muscles Spinal Cord 252 Trunk Muscles 206 Gray Matter of the Spinal Cord and Spinal Roots Anterior Muscles • Posterior Muscles • White Matter of the Spinal Cord Muscles of the Upper Limb 209 Muscles Causing Movement at the Elbow Joint Peripheral Nervous System 255 Muscles of the Lower Limb 209 Structure of a Nerve 255 Muscles Causing Movement at the Hip Cranial Nerves 257 Joint • Muscles Causing Movement at the Knee Joint • Muscles Causing Movement Spinal Nerves and Nerve Plexuses 257 at the Ankle and Foot Autonomic Nervous System 264 Somatic and Autonomic Nervous Systems Compared Developmental Aspects of the Muscular • Anatomy of the Parasympathetic Division • Anatomy System 218 of the Sympathetic Division • Autonomic Functioning Summary 219 Developmental Aspects of the Nervous Review Questions  222 System 269 Critical Thinking and Clinical Summary 273 Application Questions  223 Contents xiii Review Questions  275 Part III: Chemical Senses: Critical Thinking and Clinical Smell and Taste  298 Application Questions  277 A Closer Look The “Terrible Three” 252 Olfactory Receptors and the Sense of Smell 298 A Closer Look Tracking Down CNS Problems 270 Taste Buds and the Sense of Taste 300 Systems in Sync 272 Part IV: Developmental 8 Aspects of the Special Special Senses  301 Senses 278 Summary 303 Review Questions  305 Part I: THE EYE AND Critical Thinking and Clinical Application Questions  306 VISION 279 A Closer Look Visual Pigments—The Actual Anatomy of the Eye 279 Photoreceptors 285 External and Accessory Structures 279 A Closer Look Bringing Things into Internal Structures: The Eyeball 281 Focus 289 Layers Forming the Wall of the Eyeball • Lens Focus on Careers Physical Therapy Assistant 295 Physiology of Vision 287 Pathway of Light through the Eye and Light 9 Refraction 287 Visual Fields and Visual Pathways The Endocrine to the Brain 288 Eye Reflexes 290 System 308 Part II: THE EAR: HEARING AND The Endocrine System and Hormone BALANCE 290 Function—An Overview 309 The Chemistry of Hormones 309 Anatomy of the Ear 291 Hormone Action 309 External (Outer) Ear 291 Direct Gene Activation • Second-Messenger System Middle Ear 292 Stimuli for Control of Hormone Release 311 Internal (Inner) Ear 292 Hormonal Stimuli • Humoral Stimuli • Neural Stimuli Equilibrium 292 The Major Endocrine Organs 312 Static Equilibrium 293 Pituitary Gland and Hypothalamus 313 Dynamic Equilibrium 293 Pituitary-Hypothalamus Relationships Pineal Gland 317 Hearing 296 Thyroid Gland 317 Hearing and Equilibrium Deficits 297 Parathyroid Glands 319 Thymus 320 xiv Contents Chapter 9, continued Developmental Aspects of Blood 352 Adrenal Glands 320 Summary 353 Hormones of the Adrenal Cortex • Hormones of the Review Questions  354 Adrenal Medulla Pancreatic Islets 323 Critical Thinking and Clinical Application Questions  355 Gonads 327 Hormones of the Ovaries • Hormones of the Testes Focus on Careers Phlebotomy Technician 350 Other Hormone-Producing Tissues and Organs 327 Developmental Aspects of the Endocrine System 331 Summary 333 Review Questions  335 11  he Cardiovascular T System 356 The Heart 357 Critical Thinking and Clinical Anatomy of the Heart 357 Application Questions  336 Size, Location, and Orientation • Coverings and Walls A Closer Look Potential Uses of the Heart for Growth Hormone 316 Chambers and Associated Great Vessels 358 Systems in Sync 332 Heart Valves 361 Cardiac Circulation 10 Physiology of the Heart 364 Intrinsic Conduction System of the Heart: Setting the Basic Rhythm • Cardiac Cycle and Heart Sounds Blood 337 • Cardiac Output Blood Vessels 370 Composition and Functions Microscopic Anatomy of Blood Vessels 370 of Blood 337 Tunics • Structural Differences in Arteries, Veins, and Capillaries Components 338 Gross Anatomy of Blood Vessels 373 Physical Characteristics and Volume 338 Major Arteries of the Systemic Circulation • Major Plasma 338 Veins of the Systemic Circulation • Special Circulations Formed Elements 340 Physiology of Circulation 380 Erythrocytes • Leukocytes • Platelets Arterial Pulse • Blood Pressure • Capillary Exchange of Gases and Nutrients • Fluid Movements at Capillary Beds Hematopoiesis (Blood Cell Formation) 345 Formation of Red Blood Cells • Formation of White Developmental Aspects of the Blood Cells and Platelets Cardiovascular System 389 Hemostasis 347 Summary 392 Phases of Hemostasis 347 Review Questions  394 Disorders of Hemostasis 348 Critical Thinking and Clinical Blood Groups and Transfusions 349 Application Questions  396 Human Blood Groups 349 A Closer Look Electrocardiography: (Don’t) Be Still My Heart 367 Blood Typing 352 Contents xv A Closer Look Atherosclerosis? Summary 431 Get Out the Cardiovascular Drāno! 386 Review Questions  433 Systems in Sync 391 Critical Thinking and Clinical Application Questions  435 12 A Closer Look AIDS: An Ongoing  he Lymphatic T Pandemic 428 System and Body Systems in Sync 430 Defenses 398 Part I: The Lymphatic System 398 13  The Respiratory System 436 Lymphatic Vessels 399 Functional Anatomy of the Respiratory System 436 Lymph Nodes 400 The Nose 437 Other Lymphoid Organs 402 The Pharynx 438 The Larynx 439 Part II: BODY DEFENSES 403 The Trachea 440 The Main Bronchi 440 Innate Body Defenses 404 The Lungs 441 Surface Membrane Barriers 404 The Bronchial Tree • Respiratory Zone Structures and Internal Defenses: Cells and Chemicals 406 the Respiratory Membrane Natural Killer Cells • Inflammatory Response • Phagocytes • Antimicrobial Proteins • Fever Respiratory Physiology 445 Mechanics of Breathing 445 Adaptive Body Defenses 410 Inspiration • Expiration Antigens 412 Respiratory Volumes and Capacities 448 Cells of the Adaptive Defense System: An Nonrespiratory Air Movements 449 Overview 412 Respiratory Sounds 449 Lymphocytes • Antigen-Presenting Cells Humoral (Antibody-Mediated) Immune External Respiration, Gas Transport, and Response 415 Internal Respiration 449 Active and Passive Humoral Immunity • Antibodies External Respiration • Gas Transport in the Blood • Internal Respiration Cellular (Cell-Mediated) Immune Response 420 Control of Respiration 452 Organ Transplants and Rejection 422 Neural Regulation: Setting the Basic Rhythm Disorders of Immunity 425 • Nonneural Factors Influencing Respiratory Rate and Depth Part III: DEVELOPMENTAL Respiratory Disorders 454 ASPECTS OF THE LYMPHATIC SYSTEM AND BODY Developmental Aspects of the DEFENSES 429 Respiratory System 457 Summary 459 xvi Contents Chapter 13, continued Part II: Nutrition and Review Questions  461 Metabolism 487 Critical Thinking and Clinical Nutrition 487 Application Questions  462 Dietary Recommendations 487 A Closer Look Too Clean for Dietary Sources of the Major Nutrients 488 Our Own Good? 456 Carbohydrates • Lipids • Proteins • Vitamins Systems in Sync 458 • Minerals Metabolism 490 14  The Digestive Carbohydrate, Fat, and Protein Metabolism in Body Cells 490 System and Body Carbohydrate Metabolism • Fat Metabolism • Protein Metabolism Metabolism 463 The Central Role of the Liver in Metabolism 494 General Metabolic Functions • Cholesterol Metabolism Part I: Anatomy and and Transport Physiology of the Digestive Body Energy Balance 497 Regulation of Food Intake • Metabolic Rate and Body System 463 Heat Production • Body Temperature Regulation Anatomy of the Digestive Part III: Developmental System 463 Aspects of the Digestive Organs of the Alimentary Canal 464 Mouth • Pharynx • Esophagus • Stomach • Small System and Metabolism 501 Intestine • Large Intestine Summary 506 Accessory Digestive Organs 474 Review Questions  508 Teeth • Salivary Glands • Pancreas • Liver and Gallbladder Critical Thinking and Clinical Application Questions  510 Functions of the Digestive A Closer Look Peptic Ulcers: “Something System 476 Is Eating at Me” 486 Overview of Gastrointestinal Processes and Controls 477 A Closer Look Obesity: Magical Solution Wanted 503 Activities Occurring in the Mouth, Pharynx, and Esophagus 480 Systems in Sync 505 Food Ingestion and Breakdown • Food Propulsion— 15  Swallowing and Peristalsis Activities of the Stomach 481 Food Breakdown • Food Propulsion The Urinary Activities of the Small Intestine 483 System 511 Chyme Breakdown and Absorption • Chyme Propulsion Activities of the Large Intestine 485 Kidneys 512 Nutrient Breakdown and Absorption • Propulsion Location and Structure 512 of Food Residue and Defecation Kidney Structure • Blood Supply Nephrons 513 Contents xvii Urine Formation and Characteristics 516 Epididymis • Ductus Deferens • Urethra Glomerular Filtration • Tubular Reabsorption • Tubular Accessory Glands and Semen 541 Secretion • Nitrogenous Wastes • Characteristics of Urine Seminal Vesicles • Prostate • Bulbo-urethral Glands • Semen Ureters, Urinary Bladder, External Genitalia 542 and Urethra 520 Ureters 520 Male Reproductive Functions 543 Urinary Bladder 521 Spermatogenesis 543 Urethra 523 Testosterone Production 545 Micturition 523 Anatomy of the Female Reproductive Fluid, Electrolyte, and Acid-Base System 547 Balance 524 Ovaries 547 Maintaining Water Balance of Blood 524 Duct System 547 Body Fluids and Fluid Compartments • The Link Uterine Tubes • Uterus • Vagina between Water and Electrolytes • Regulation of Water External Genitalia and Female Perineum 550 Intake and Output Maintaining Electrolyte Balance 527 Female Reproductive Functions Maintaining Acid-Base Balance of Blood 529 and Cycles 551 Blood Buffers • Respiratory Mechanisms • Renal Oogenesis and the Ovarian Cycle 551 Mechanisms Hormone Production by the Ovaries 553 Developmental Aspects of the Urinary Uterine (Menstrual) Cycle 554 System 531 Mammary Glands 554 Summary 535 Review Questions  536 Pregnancy and Embryonic Development 557 Critical Thinking and Clinical Application Questions  537 Accomplishing Fertilization 558 A Closer Look Renal Failure and Events of Embryonic and Fetal Development 559 the Artificial Kidney 523 Effects of Pregnancy on the Mother 563 Focus on Careers Licensed Practical Anatomical Changes • Physiological Changes Nurse (LPN) 532 Childbirth 565 Systems in Sync 534 Initiation of Labor • Stages of Labor 16  Developmental Aspects of the The Reproductive Reproductive System 567 System 538 Summary 572 Review Questions  574 Critical Thinking and Clinical Anatomy of the Male Reproductive Application Questions  576 System 539 A Closer Look Contraception: Preventing Testes 539 Pregnancy 568 Duct System 539 Systems in Sync 571 xviii Contents Appendixes Appendix D K  ey Information about Vitamins and Many Essential Appendix A: A  nswers to Did You Get It? Minerals 587 Questions and Multiple Choice Glossary 591 Review Questions 577 Credits 604 Appendix B: W  ord Roots, Prefixes, and Suffixes 584 Subject Index 605 Appendix C: P  eriodic Table of the Elements 586 1 The Human Body: An Orientation WHAT Anatomy is the study of the structure, or HOW physical form, of the The function, or body. physiology, of each body part and the body as a whole is dependent on the anatomy of those parts; in other words, structure determines function. WHY This text will help you learn structures and functions INSTRUCTORS so you can understand the role of New Building individual organs and body Vocabulary Coaching systems and how they interact Activities for this to support life. chapter are assignable in An Overview of Anatomy the seeds. Adults become upset when their hearts pound, when they have uncontrollable hot flashes, and Physiology or when they cannot keep their weight down. ➔ Learning Objectives Anatomy and physiology, subdivisions of biol- ogy, explore many of these topics as they describe □□ Define anatomy and physiology. how our bodies are put together and how they □□ Explain how anatomy and physiology are related. work. Most of us are naturally curious about our bodies; Anatomy we want to know what makes us tick. Infants can keep themselves happy for a long time staring at Anatomy (ah-nat′o-me) is the study of the structure their own hands or pulling their mother’s nose. and shape of the body and its parts and their rela- Older children wonder where food goes when tionships to one another. Whenever we look at our they swallow it, and some believe that they will own body or study large body structures such as the grow a watermelon in their belly if they swallow heart or bones, we are observing gross ­anatomy; 1 2 Essentials of Human Anatomy and Physiology that is, we are studying large, easily observable structures. Indeed, the term anatomy, derived Levels of Structural from the Greek words meaning to cut (tomy) apart Organization (ana), is related most closely to gross anatomical ➔ Learning Objectives studies because in such studies, preserved animals □□ Name the six levels of structural organization that or their organs are dissected (cut up) to be exam- make up the human body, and explain how they ined. Microscopic anatomy, in contrast, is the study are related. of body structures that are too small to be seen □□ Name the organ systems of the body, and briefly with the naked eye. The cells and tissues of the state the major functions of each system. body can only be seen through a microscope. □□ Identify and classify by organ system all organs discussed. Physiology Physiology (fiz″e-ol′o-je) is the study of how the From Atoms to Organisms body and its parts work or function ( physio = The human body exhibits many levels of structural nature; ology = the study of). Like anatomy, physi- complexity (Figure 1.1). The simplest level of the ology has many subdivisions. For example, neu- structural ladder is the chemical level (covered rophysiology explains the workings of the nervous in Chapter 2). At this level, atoms, tiny building system, and cardiac physiology studies the func- blocks of matter, combine to form molecules such tion of the heart. as water, sugar, and proteins, like those that make up our muscles. Molecules, in turn, associate in Relationship between specific ways to form microscopic cells, the small- Anatomy and Physiology est units of all living things. (We will examine the Anatomy and physiology are always inseparable. cellular level in Chapter 3.) All cells have some The parts of your body form a well-organized unit, common structures and functions, but individual and each of those parts has a job to do to make cells vary widely in size, shape, and their particu- the body operate as a whole. Structure determines lar roles in the body. what functions can take place. For example, the The simplest living creatures are composed of lungs are not muscular chambers like the heart single cells, but in complex organisms such as and so cannot pump blood through the body, trees or human beings, the structural ladder con- but because the walls of their air sacs are very tinues on to the tissue level. Tissues consist of thin, they can exchange gases and provide oxygen groups of similar cells that have a common func- to the body. We stress the intimate relationship tion. There are four basic tissue types, and each between anatomy and physiology throughout this plays a definite but different role in the body. (We text to make your learning meaningful. discuss tissues in Chapter 3.) An organ is a structure composed of two or Did You Get It? more tissue types that performs a specific function 1. Why would you have a hard time learning and for the body. At the organ level of organization, understanding physiology if you did not also extremely complex functions become possible. understand anatomy? For example, the small intestine, which digests 2. Kidney function, bone growth, and beating of the heart are all topics of anatomy. True or false? and absorbs food, is composed of all four tissue types. An organ system is a group of organs that For answers, see Appendix A. work together to accomplish a common purpose. ➔ For example, the heart and blood vessels of the CONCEPTLINK cardiovascular system circulate blood continuously Throughout this text, Concept Links will highlight links to carry nutrients and oxygen to all body cells. between concepts and/or organ systems. Keep in mind In all, 11 organ systems make up the living that although discussions of the systems are separated human being, or the organism, which represents into chapters for detailed study, the overall goal of this the highest level of structural organization, the text is for you not only to gain an understanding of organismal level. The organismal level is the sum each individual system, but also to learn how the body total of all structural levels working together to systems interact to sustain life. ➔ keep us alive. The major organs of each system Chapter 1: The Human Body: An Orientation 3 1 Smooth muscle cell Atoms 1 Chemical level Molecules Atoms combine to 2 Cellular level form molecules. Cells are made up of molecules. Smooth muscle tissue 3 Tissue level Blood Tissues consist of vessels similar types of cells. Heart Epithelial tissue Smooth muscle tissue Blood vessel (organ) Cardio– Connective vascular tissue system 4 Organ level Organs are made up of 5 Organ system level different types of tissues. 6 Organismal level Organ systems consist of Human organisms are different organs that work made up of many organ together closely. systems. Figure 1.1 Levels of structural organization. In this diagram, components of the cardiovascular system are used to illustrate the levels of structural organization in a human being. are shown in Figure 1.2 on pp. 5–6. Refer to the waterproofs the body and cushions and protects figure as you read through the following descrip- the deeper tissues from injury. With the help of tions of the organ systems. sunlight, it produces vitamin D. It also excretes salts in perspiration and helps regulate body tem- Organ System Overview perature. Sensory receptors located in the skin Integumentary System alert us to what is happening at the body surface. The integumentary (in-teg″u-men′tar-e) system Skeletal System is the external covering of the body, or the skin, including the hair and fingernails (Figure 1.2a). It The skeletal system consists of bones, cartilages, and joints (Figure 1.2b). It supports the body and 4 Essentials of Human Anatomy and Physiology provides a framework that the skeletal muscles use in common is that they all secrete hormones, to cause movement. It also has protective func- which regulate other structures. The body func- tions (for example, the skull encloses and protects tions controlled by hormones are many and var- the brain), and the cavities of the skeleton are the ied, involving every cell in the body. Growth, sites where blood cells are formed. The hard sub- reproduction, and the use of nutrients by cells are stance of bones acts as a storehouse for minerals. all controlled (at least in part) by hormones. Muscular System Cardiovascular System The muscles of the body have only one function— The primary organs of the cardiovascular sys- to contract, or shorten. When this happens, move- tem are the heart and blood vessels (Figure 1.2f). ment occurs. The mobility of the body as a whole Using blood as a carrier, the cardiovascular system reflects the activity of skeletal muscles, the large, delivers oxygen, nutrients, hormones, and other fleshy muscles attached to bones (Figure 1.2c). substances to, and picks up wastes such as carbon When these contract, you are able to stand erect, dioxide from, cells near sites of exchange. White walk, jump, grasp, throw a ball, or smile. The skel- blood cells and chemicals in the blood help to etal muscles form the muscular system. These protect the body from such foreign invaders as muscles are distinct from the muscles of the heart bacteria, viruses, and tumor cells. The heart pro- and of other hollow organs, which move fluids pels blood out of its chambers into blood vessels (such as blood or urine) or other substances (such to be transported to all body tissues. as food) along definite pathways within the body. Lymphatic System Nervous System The role of the lymphatic system comple- The nervous system is the body’s fast-acting con- ments that of the cardiovascular system. Its organs trol system. It consists of the brain, spinal cord, include lymphatic vessels, lymph nodes, and other nerves, and sensory receptors (Figure 1.2d). The lymphoid organs such as the spleen and tonsils body must be able to respond to stimuli com- (Figure 1.2g). When fluid is leaked into tissues ing from outside the body (such as light, sound, from the blood, lymphatic vessels return it to the or changes in temperature) and from inside the bloodstream so that there is enough blood to con- body (such as decreases in oxygen or stretching tinuously circulate through the body. The lymph of tissue). The sensory receptors detect changes in nodes and other lymphoid organs help to cleanse temperature, pressure, or light, and send messages the blood and house white blood cells involved in (via electrical signals called nerve impulses) to the immunity. central nervous system (brain and spinal cord) so that it is constantly informed about what is going Respiratory System on. The central nervous system then assesses this The job of the respiratory system is to keep the information and responds by activating the appro- body supplied with oxygen and to remove car- priate body effectors (muscles or glands, which are bon dioxide. The respiratory system consists of organs that produce secretions). the nasal passages, pharynx, larynx, trachea, bron- chi, and lungs (Figure 1.2h). Within the lungs are Endocrine System tiny air sacs. Gases are exchanged with the blood Like the nervous system, the endocrine (en′do-krin) through the thin walls of these air sacs. system controls body activities, but it acts much more slowly. Endocrine glands produce chemi- Digestive System cal molecules called hormones and release them The digestive system is basically a tube running into the blood to travel to relatively distant target through the body from mouth to anus. The organs organs. of the digestive system include the oral cavity The endocrine glands include the pituitary, (mouth), esophagus, stomach, small and large thyroid, parathyroids, adrenals, thymus, pancreas, intestines, and rectum plus a number of accessory pineal, ovaries (in the female), and testes (in the organs (liver, salivary glands, pancreas, and oth- male) (Figure 1.2e). The endocrine glands are not ers) (Figure 1.2i). Their role is to break down food connected anatomically in the same way that the and deliver the resulting nutrients to the blood for parts of other organ systems are. What they have dispersal to body cells. The breakdown activities Hair 1 Skeletal Cartilages muscles Skin Joint Bones Fingernails (a) Integumentary System (b) Skeletal System (c) Muscular System Forms the external body covering; Protects and supports body organs; Allows manipulation of the protects deeper tissue from injury; provides a framework the muscles environment, locomotion, and facial synthesizes vitamin D; location of use to cause movement; blood cells expression; maintains posture; sensory receptors (pain, pressure, are formed within bones; stores produces heat. etc.) and sweat and oil glands. minerals. Pineal gland Brain Pituitary gland Sensory Thyroid gland receptor (parathyroid glands Spinal on posterior aspect) Heart cord Thymus gland Adrenal glands Nerves Pancreas Testis (male) Blood vessels Ovary (female) (d) Nervous System (e) Endocrine System (f) Cardiovascular System Fast-acting control system of the Glands secrete hormones that Blood vessels transport blood, which body; responds to internal and regulate processes such as growth, carries oxygen, nutrients, hormones, external changes by activating reproduction, and nutrient use by carbon dioxide, wastes, etc.; the heart appropriate muscles and glands. body cells. pumps blood. Figure 1.2 The body’s organ systems. (Figure continues on page 6.) Nasal cavity Oral cavity Pharynx Larynx Esophagus Trachea Stomach Bronchi Small Lymph Lungs intestine nodes Large intestine Rectum Lymphatic vessels (g) Lymphatic System (h) Respiratory System (i) Digestive System Picks up fluid leaked from blood Keeps blood constantly supplied Breaks food down into absorbable vessels and returns it to blood; with oxygen and removes carbon nutrients that enter the blood for disposes of debris in the lymphatic dioxide; the gaseous exchanges distribution to body cells; indigestible stream; houses white blood cells occur through the walls of the air foodstuffs are eliminated as feces. involved in immunity. sacs of the lungs. Mammary glands Kidney Prostate (in breasts) Seminal gland Uterine Ureter vesicles tube Urinary Ovary bladder Uterus Penis Urethra Testis Scrotum Vagina (j) Urinary System (k) Male Reproductive System (l) Female Reproductive System Eliminates nitrogen-containing Overall function of the reproductive system is production of offspring. Testes wastes from the body; regulates produce sperm and male sex hormone; ducts and glands aid in delivery of viable water, electrolyte, and acid-base sperm to the female reproductive tract. Ovaries produce eggs and female sex balance of the blood. hormones; remaining structures serve as sites for fertilization and development of the fetus. Mammary glands of female breasts produce milk to nourish the newborn. Figure 1.2 (continued) The body’s organ systems. Chapter 1: The Human Body: An Orientation 7 that begin in the mouth are completed in the small intestine. From that point on, the major function Maintaining Life 1 of the digestive system is to reabsorb water. The ➔ Learning Objectives undigested food that remains in the tract leaves □□ List eight functions that humans must perform to the body through the anus as feces. The liver maintain life. is considered a digestive organ because the bile □□ List the five survival needs of the human body. it produces helps to break down fats. The pan- creas, which delivers digestive enzymes to the Necessary Life Functions small intestine, has both endocrine and digestive Now that we have introduced the structural levels functions. composing the human body, a question naturally follows: What does this highly organized human Urinary System body do? Like all complex animals, human beings A normal part of healthy body function is the maintain their boundaries, move, respond to envi- production of waste by-products, which must be ronmental changes, take in and digest nutrients, disposed of. One type of waste contains nitro- carry out metabolism, dispose of wastes, repro- gen (examples are urea and uric acid), which duce themselves, and grow. results when the body cells break down proteins Organ systems do not work in isolation; instead, and nucleic acids, which are genetic information they work together to promote the well-being of ­molecules. The urinary system removes the the entire body (Figure 1.3). Because this theme is nitrogen-containing wastes from the blood and emphasized throughout this text, it is worthwhile to flushes them from the body in urine. This sys- identify the most important organ systems contrib- tem, often called the excretory system, is com- uting to each of the necessary life functions. Also, posed of the kidneys, ureters, bladder, and urethra as you study this figure, you may want to refer to (Figure 1.2j). Other important functions of this sys- the more detailed descriptions of the organ systems tem include maintaining the body’s water and salt just provided (pp. 3–7 and in Figure 1.2). (electrolyte) balance, regulating the acid-base bal- ance of the blood, and helping to regulate normal Maintaining Boundaries blood pressure. Every living organism must be able to maintain its boundaries so that its “inside” remains distinct Reproductive System from its “outside.” Every cell of the human body is The role of the reproductive system is to pro- surrounded by an external membrane that sepa- duce offspring. The male testes produce sperm. rates its contents from the outside interstitial fluid Other male reproductive system structures are the (fluid between cells) and allows entry of needed scrotum, penis, accessory glands, and the duct substances while generally preventing entry of system, which carries sperm to the outside of the potentially damaging or unnecessary substances. body (Figure 1.2k). The female ovaries produce The body as a whole is also enclosed by the eggs, or ova; the female duct system consists of integumentary system, or skin. The integumen- the uterine tubes, uterus, and vagina (Figure 1.2l). tary system protects internal organs from drying The uterus provides the site for the development out (which would be fatal), from pathogens, and of the fetus (immature infant) once fertilization from the damaging effects of heat, sunlight, and has occurred. an unbelievable number of chemical substances in the external environment. Did You Get It? 3. At which level of structural organization is the Movement stomach? At which level is a glucose molecule? Movement includes all the activities promoted by 4. Which organ system includes the trachea, lungs, the muscular system, such as propelling ourselves nasal cavity, and bronchi? 5. Which system functions to remove wastes and help from one place to another (by walking, swim- regulate blood pressure? ming, and so forth) and manipulating the exter- nal environment with our fingers. The skeletal For answers, see Appendix A. system provides the bones that the muscles pull on as they work. Movement also occurs when substances such as blood, foodstuffs, and urine Digestive system Respiratory system Takes in nutrients, digests them Takes in oxygen, which is (part of metabolism), and excretes required for metabolism, and unabsorbed matter (feces) excretes carbon dioxide Food O2 CO2 Cardiovascular system Via the blood, distributes oxygen and nutrients to all body cells and delivers wastes and carbon dioxide to disposal organs Blood CO2 O2 Heart Urinary system Nutrients Excretes nitrogen-containing wastes and excess ions Interstitial fluid Nutrients and wastes pass between blood and cells via the interstitial fluid Integumentary system Feces are Protects the body as a whole Urine is excreted from the external environment excreted by maintaining boundaries Figure 1.3 Examples of interrelationships among organ systems that illustrate life functions. are propelled through the internal organs of the pan). You do not need to think about it—it just cardiovascular, digestive, and urinary systems, happens! Likewise, when the amount of carbon respectively. dioxide in your blood rises to a dangerously high level, your breathing rate speeds up to blow off Responsiveness the excess carbon dioxide. Responsiveness, or irritability, is the ability to Because nerve cells are highly irritable and sense changes (stimuli) in the environment and can communicate rapidly with each other via elec- then to react to them. For example, if you acci- trical impulses, the nervous system bears the major dentally touch a hot pan, you involuntarily pull responsibility for responsiveness. However, all your hand away from the painful stimulus (the body cells are responsive to some extent. Chapter 1: The Human Body: An Orientation 9 Digestion by an increase in the number of cells. For growth Digestion is the process of breaking down to occur, cell-constructing activities must occur at 1 ingested food into simple molecules that can then a faster rate than cell-destroying ones. Hormones be absorbed into the blood. The nutrient-rich released by the endocrine system play a major role blood is then distributed to all body cells by the in directing growth. cardiovascular system, where body cells use these Survival Needs simple molecules for energy and raw materials. The goal of nearly all body systems is to maintain Metabolism life. However, life is extraordinarily fragile and Metabolism is a broad term that refers to all requires that several factors be available. These chemical reactions that occur within the body and factors, which we will call survival needs, include all of its cells. It includes breaking down com- nutrients (food), oxygen, water, and appropriate plex substances into simpler building blocks (as in temperature and atmospheric pressure. digestion), making larger structures from smaller Nutrients, which the body takes in through ones, and using nutrients and oxygen to produce food, contain the chemicals used for energy and molecules of adenosine triphosphate (ATP), the cell building. Carbohydrates are the major energy- energy-rich molecules that power cellular activi- providing fuel for body cells. Proteins and, to a ties. Metabolism depends on the digestive and lesser extent, fats are essential for building cell respiratory systems to make nutrients and oxygen structures. Fats also cushion body organs and pro- available to the blood and on the cardiovascu- vide reserve fuel. Minerals and vitamins are lar system to distribute these needed substances required for the chemical reactions that go on in throughout the body. Metabolism is regulated cells and for oxygen transport in the blood. chiefly by hormones secreted by the glands of the All the nutrients in the world are useless unless endocrine system. oxygen is also available. Because the chemical reactions that release energy from foods require Excretion oxygen, human cells can survive for only a few Excretion is the process of removing excreta minutes without it. It is made available to the (ek-skre′tah), or wastes, from the body. Several blood and body cells by the cooperative efforts of organ systems participate in excretion. For exam- the respiratory and cardiovascular systems. ple, the digestive system rids the body of indigest- Water accounts for 60 to 80 percent of body ible food residues in feces, the urinary system weight, depending on the age of the individual. It is disposes of nitrogen-containing metabolic wastes the single most abundant chemical substance in the in urine, and the skin disposes of various waste body and provides the fluid base for body secre- products as components of sweat. tions and excretions. We obtain water chiefly from ingested foods or liquids, and we lose it by evapora- Reproduction tion from the lungs and skin and in body excretions. Reproduction, the production of offspring, can If chemical reactions are to continue at life- occur on the cellular or organismal level. In cel- sustaining levels, normal body temperature lular reproduction, the original cell divides, pro- must be maintained. If body temperature drops ducing two identical daughter cells that may then below 37°C (98.6°F), metabolic reactions become be used for body growth or repair. Reproduction slower and slower and finally stop. If body tem- of the human organism is the task of the organs perature is too high, chemical reactions proceed of the reproductive system, which produce sperm too rapidly, and body proteins begin to break and eggs. When a sperm unites with an egg, a down. At either extreme, death occurs. Most body fertilized egg forms, which then develops into a heat is generated by the activity of the skeletal baby within the mother’s body. The function of the muscles and dissipated via blood circulating close reproductive system is regulated very precisely by to the skin surface or by the evaporation of sweat. hormones of the endocrine system. The force exerted on the surface of the body by the weight of air is referred to as atmospheric Growth pressure. Breathing and the exchange of oxygen Growth can be an increase in cell size or an and carbon dioxide in the lungs depend on increase in body size that is usually accomplished (Text continues on page 12.) A CLOSER Medical Imaging: Illuminating LOOK the Body I maging procedures are important diagnostic tools that are either mini- mally invasive or not invasive at all. By body is probed with pulses of sound waves, which cause echoes when reflected and scattered by body tis- Currently PET can reveal signs of trou- ble in people with undiagnosed Alzheimer’s disease (AD) because bombarding the body with different sues. The echoes are analyzed by regions of beta-amyloid accumulation forms of energy, medical imaging computer to construct visual images (a defining characteristic of AD) show techniques can reveal the structure of of body organs, much like sonar is up in brilliant red and yellow when internal organs, show blood flow in used to map the ocean floor. that molecule is tagged. By tagging real time, and even determine the Because of its safety, ultrasound is glucose, we can observe that brain density of bone. the imaging technique of choice for ­tissue in areas of impairment or areas Until about 50 years ago, the determining fetal age and position with Alzheimer’s plaques use far less magical but murky X ray was the only and locating the placenta; see photo glucose compared to normal brain means of peering into a living body (c). Because sound waves have very ­tissue as shown in photo (d). without performing surgery. The low penetrating power and are rap- Perhaps the best known of these X-ray film is a shadowy negative idly scattered in air, sonography newer imaging devices is computed image of internal structures produced does not visualize air-filled structures tomography (CT), a refined version by directing electromagnetic waves (the lungs) or those surrounded of X ray that eliminates the confusion of very short wavelength at the body. by bone (the brain and spinal resulting from images of overlapping X rays are best used to visualize hard, cord) well. structures. A CT scanner takes “pic- bony structures and locate abnor- Though nuclear medicine, which tures” of a thin slice of the body, mally dense structures (tumors, uses radioisotopes to scan the about as thick as a dime. Different tis- tuberculosis nodules) in the lungs body, was developed in the 1950s, sues absorb the radiation in varying and breasts. it was not until the 1970s that a amounts. The device’s computer Two examples of low-dose X-ray ­powerful technique for visualizing translates this information into a procedures are mammography and metabolic activities, PET, was intro- detailed, cross-sectional picture of the bone densitometry. A mammogram duced. The 1970s also introduced CT, body region scanned; see photo (e). is used to identify changes in breast an X-ray–based scanning technique, CT scans are at the forefront in evalu- tissue, including dense masses or cal- and MRI scanning techniques, which ating most problems that affect the cifications. A mammogram is per- use powerful magnets. brain and abdomen, and their clarity formed by compressing the breast in a Positron emission tomography has all but eliminated exploratory sur- special X-ray machine because thinner (PET) requires an injection of short- gery. Special ultrafast CT scanners tissue results in a better image; see lived radioisotopes that have been have produced a technique called photo (a). Bone densitometry tagged to biological molecules (such dynamic spatial reconstruction detects the amount of calcium and as glucose) in order to view metabolic (DSR), which provides three-­ minerals stored in bone and is the processes. The patient is positioned in dimensional images of body organs major diagnostic test for osteoporosis; the PET scanner, and as the radioiso- from any angle. It also allows organ see photo (b). topes are absorbed by the most active movements and changes in internal The 1950s saw the birth of ultra- brain cells, high-energy gamma rays volumes to be observed at normal sound imaging (ultrasonogra- are produced. A computer analyzes speed, in slow motion, and at a spe- phy), which has some distinct the gamma emissions and produces a cific moment in time. The greatest advantages over other imaging tech- picture of the brain’s biochemical value of DSR has been to visualize the niques. The equipment employs activity in vivid colors. PET’s greatest heart beating and blood flowing high-frequency sound waves (ultra- clinical value has been its ability to through blood vessels. This allows sound) as its energy source. Unlike X provide insights into brain activity in medical personnel to assess heart rays, ultrasound has no known people affected by mental illness, defects, constricted blood vessels, and harmful effects on living tissues. The Alzheimer’s disease, and epilepsy. the status of coronary bypass grafts. 10 (a) Mammogram (b) Bone densitometry scan showing (c) Sonogram of a fetus. showing breast osteoporosis in the small yellow cancer. box on the neck of the femur. (d) A PET scan demonstrates glucose metabolism in a (e) CT scan showing normal brain (left). Glucose metabolism is brain tumors decreased in a brain with mild cognitive impairment (indicated by (middle), and glucose is metabolized at an even black arrows). lower level in a brain with Alzheimer’s plaques (right). A different technique is magnetic column do not impair the view of soft the powerful magnets of the MRI can resonance imaging (MRI), which tissues, such as the brain or interver- pose risks. For example, metal uses magnetic fields up to 60,000 tebral discs, the cartilage pads objects, such as implanted pacemak- times stronger than Earth’s to pry between vertebrae. MRI is also partic- ers and loose tooth fillings, can be information from body tissues. The ularly good at detecting signs of “sucked” through the body. Also, patient lies in a tubelike chamber degenerative disease such as multiple the long-term health risks of expo- within a huge magnet. Hydrogen mol- sclerosis plaques, which do not show sure to strong magnetic fields are ecules spin like tops in the magnetic up well in CT scans but are dazzlingly not clear. field, and their energy is enhanced by clear in MRI scans. As you can see, modern medical the presence of radio waves. When A variation of MRI called func- science enlists remarkable diagnostic the radio waves are turned off, tional magnetic resonance imag- tools. CT and PET scans account for energy is released and translated by a ing (fMRI) allows tracking of blood about 25 percent of all imaging. Ultra- computer into a visual image (see flow into the brain in real time. sonography, because of its safety and ­Figure 1.5, p. 16). MRI is immensely Before 1992, PET was the only way low cost, is the most widespread. popular because it can do many to match brain activity to disease. However, conventional X rays remain things a CT scan cannot. Dense struc- With no need for injections of radio- the workhorse of diagnostic imaging tures do not show up in MRI, so isotopes, fMRI provides a less invasive and still account for more than half of bones of the skull and/or vertebral alternative. Despite its advantages, all medical imaging. 11