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Principles of anatomy and physiology, 13th ed Principles of anatomy and physiology, 13th ed Document Transcript

  • Principles of ANATOMY & PHYSIOLOGY Gerard J. Tortora Bergen Community College Bryan Derrickson Valencia Community College 13th Edition John Wiley & Sons, Inc. JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:22 Page i
  • Vice President & Publisher Kaye Pace Executive Editor Bonnie Roesch Executive Marketing Manager Clay Stone Developmental Editor Mary Berry Senior Media Editor Linda Muriello Project Editor Lorraina Raccuia Program Assistant Lauren Morris Production Manager Dorothy Sinclair Production Editor Sandra Dumas Senior Illustration Editor Anna Melhorn Illustration Coordinator Claudia Volano Senior Designer Madelyn Lesure Text Designer Brian Salisbury Photo Department Manager Hilary Newman Production Management Services Ingrao Associates Page layout was completed by Laura Ierardi, LCI Design. Photo Credits Front cover photo credits (bottom left to right): (muscle) ©Mark Nielsen; (neuron cell body) ©Dr. Don Fawcett/Visuals Unlimited/Getty Images, Inc.; (ear cross-section) © Images, Inc.; (red blood cells) ©Dr. Don Fawcett/Visuals Unlimited/Getty Images, Inc.; (spinal cord) ©Ron Boardman/Stone/Getty Images, Inc. Back cover photo credits: (top left) ©Dr. Don Fawcett/Visuals Unlimited/Getty Images, Inc.; (top right) ©Ron Boardman/Stone/Getty Images, Inc.; (center left) ©Mark Nielsen; (center right) ©Dr. Don Fawcett/Visuals Unlimited/Getty Images, Inc.; (bottom) © Images, Inc. This book was typeset in 10.5/12.5 Times at Aptara® , Inc. and printed and bound by Quad Graphics. The cover was printed by Quad Graphics. Founded in 1807, John Wiley & Sons, Inc., has been a valued source of knowledge and understanding for more than 200 years, helping people around the world meet their needs and fulfill their aspirations. Our company is built on a foundation of principles that include responsibility to the communities we serve and where we live and work. In 2008, we launched a Corporate Citizenship Initiative, a global effort to address the environmental, social, economic, and ethical challenges we face in our business. Among the issues we are addressing are carbon impact, paper specifications and procurement, ethical conduct within our business and among our vendors, and community and charitable support. For more information, please visit our website: The paper in this book was manufactured by a mill whose forest management programs include sustained yield harvesting of its timberlands. Sustained yield harvesting principles ensure that the number of trees cut each year does not exceed the amount of new growth. This book is printed on acid-free paper. Copyright © 2012, 2009, 2006, 2003, 2000. © Biological Science Textbooks, Inc., and Bryan Derrickson. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030-5774, (201) 748-6011, fax (201) 748-6008. Evaluation copies are provided to qualified academics and professionals for review purposes only, for use in their courses during the next academic year. These copies are licensed and may not be sold or transferred to a third party. Upon completion of the review period, please return the evaluation copy to Wiley. Return instructions and a free-of-charge return shipping label are available at Outside of the United States, please contact your local representative. ISBN 13 978-0470-56510-0 ISBN 13 978-0470-91777-0 Printed in the United States of America. 10 9 8 7 6 5 4 3 2 1 JWCL316_fm_i-xxxiv.qxd 11/22/10 7:01 PM Page ii
  • An anatomy and physiology course can be the gateway to a grati- fying career in a whole host of health-related professions. It can also be an incredible challenge. Through years of collaboration with students and instructors alike, we have come to intimately understand not only the material but also the evolving dynamics of teaching and learning A&P. So with every new edition, it’s our goal to find new ways to help instructors teach more easily and effectively and students to learn in a way that sticks. We believe we bring together experience and innovation like no one else, offering a unique solution for A&P designed to help instructors and students succeed together. From constantly evolving anima- tions and visualizations to design based on optimal learning to lessons firmly grounded in learning outcomes, everything is designed with the goal of helping instructors like you teach in a way that inspires confidence and resilience in students and better learning outcomes. The thirteenth edition of Principles of Anatomy and Physiology, integrated with WileyPLUS, builds students’ confidence; it takes the guesswork out of studying by providing students with a clear roadmap (one that tells them what to do, how to do it, and if they did it right). Students will take more initiative, so instructors can have greater impact. Principles of Anatomy and Physiology 13e continues to offer a balanced presentation of content under the umbrella of our primary and unifying theme of homeostasis, supported by relevant discus- sions of disruptions to homeostasis. In addition, years of student feedback have convinced us that readers learn anatomy and physiology more readily when they remain mindful of the relationship between structure and function. As a writing team—an anatomist and a physiologist—our very different specializations offer practical advantages in fine-tuning the balance between anatomy and physiology. On the following pages students will discover the tips and tools needed to make the most of their study time using the integrated text and media. Instructors will gain an overview of the changes to this edition and of the resources available to create dynamic classroom experiences as well as build meaningful assessment opportunities. Both students and instructors will be interested in the outstanding resources available to seamlessly link laboratory activity with lecture presentation and study time. HELPING TEACHERS AND STUDENTS SUCCEED TOGETHER iii JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:22 Page iii
  • Studying the figures in this book is as important as read- ing the narrative. The tools described here will help you understand the concepts being presented in any figure and ensure that you get the most out of the visuals. N O T E S T O S T U D E N T S Anatomy and Physiology Is a Visual Science The challenges of learning anatomy and physiology can be complex and time-consuming. This textbook and WileyPLUS for Anatomy and Physiology have been carefully designed to maximize your study time by simplifying the choices you make in deciding what to study and how to study it, and in assessing your under- standing of the content. MP3 DOWNLOADS. In each chapter you will find that several illustrations are marked with an icon that looks like an iPod. This indicates that an audio file that narrates and discusses the important elements of that particular illustration is available. You can access these downloads on the student companion web- site or within WileyPLUS. iv Greater curvature BODY Rugae of mucosa Lesser curvature (b) Anterior view of internal anatomy Pyloric sphincter Duodenum PYLORUS PYLORIC ANTRUM Esophagus CARDIA FUNDUS PYLORIC CANAL CARDIA BODY FUNDUS Serosa Muscularis: Longitudinal layer Circular layer Oblique layer Rugae of mucosa PYLORIC CANAL Pyloric sphincter Duodenum Greater curvature Esophagus Lower esophageal sphincter Lesser curvature PYLORUS PYLORIC ANTRUM (a) Anterior view of regions of stomach FUNCTIONS OF THE STOMACH 1. Mixes saliva, food, and gastric juice to form chyme. 2. Serves as reservoir for food before release into small intestine. 3. Secretes gastric juice, which contains HCl (kills bacteria and denatures protein), pepsin (begins the digestion of proteins), intrinsic factor (aids absorption of vitamin B12), and gastric lipase (aids digestion of triglycerides). 4. Secretes gastrin into blood. Figure 24.11 External and internal anatomy of the stomach. The four regions of the stomach are the cardia, fundus, body, and pyloric part. After a very large meal, does your stomach still have rugae? Figure 23.17 Changes in partial pressures of oxygen and carbon dioxide (in mmHg) during external and internal respiration. Gases diffuse from areas of higher partial pressure to areas of lower partial pressure. What causes oxygen to enter pulmonary capillaries from alveoli and to enter tissue cells from systemic capillaries? CO2 exhaled O2 inhaled Atmospheric air: PO2 = 159 mmHg PCO2 = 0.3 mmHg Alveoli Alveolar air: PO2 = 105 mmHg PCO2 = 40 mmHg Pulmonary capillaries Systemic tissue cells: PO2 = 40 mmHg PCO2 = 45 mmHg To left atrium To tissue cells Systemic capillaries To lungs (a) External respiration: pulmonary gas exchange (b) Internal respiration: systemic gas exchange To right atrium Oxygenated blood: PO2 = 100 mmHg PCO2 = 40 mmHg Deoxygenated blood: PO2 = 40 mmHg PCO2 = 45 mmHg CO2 O2 CO2 O2 LEGEND. Read this first. It explains what the figure is about. KEY CONCEPT STATEMENT. Indicated by a “key” icon, this reveals a basic idea portrayed in the figure. ORIENTATION DIAGRAM. Added to many figures, this small diagram helps you under- stand the perspective from which you are viewing a particular piece of anatomical art. FIGURE QUESTION. Found at the bottom of each figure and accompanied by a “question mark” icon, this serves as a self-check to help you understand the material as you go along. FUNCTIONS BOX. Included with selected figures, these provide a brief summary of the functions of the anatomical structure or system depicted. JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:23 Page iv
  • v There are many visual resources within WileyPLUS, in addition to the art from your text. These visual aids can help you master the topic you are study- ing. Examples closely integrated with the reading material include animations, cadaver video clips, and Real Anatomy Views. Anatomy Drill and Practice lets you test your knowledge of structures with simple-to-use drag-and-drop labeling exercises or fill-in-the-blank labeling. You can drill and practice on these activities using illustrations from the text, cadaver photographs, histology micrographs, or lab models. N O T E S T O S T U D E N T S Physiology of Hearing The following events are involved in hearing (Figure 17.22): G1 The auricle directs sound waves into the external auditory canal. G2 When sound waves strike the tympanic membrane, the alter- nating waves of high and low pressure in the air cause the tympanic membrane to vibrate back and forth. The tympanic membrane vibrates slowly in response to low-frequency (low-pitched) sounds and rapidly in response to high- frequency (high-pitched) sounds. G3 The central area of the tympanic membrane connects to the malleus, which vibrates along with the tympanic membrane. This vibration is transmitted from the malleus to the incus and then to the stapes. G4 As the stapes moves back and forth, its oval-shaped footplate, which is attached via a ligament to the circumference of the oval window, vibrates in the oval window. The vibrations at the oval window are about 20 times more vigorous than the tym- panic membrane because the auditory ossicles efficiently transmit small vibrations spread over a large surface area (the tympanic membrane) into larger vibrations at a smaller surface (the oval window). G5 The movement of the stapes at the oval window sets up fluid pressure waves in the perilymph of the cochlea. As the oval window bulges inward, it pushes on the perilymph of the scala vestibuli. G6 Pressure waves are transmitted from the scala vestibuli to the scala tympani and eventually to the round window, causing it to bulge outward into the middle ear. (See G9 in the figure.) G7 The pressure waves travel through the perilymph of the scala vestibuli, then the vestibular membrane, and then move into the endolymph inside the cochlear duct. G8 The pressure waves in the endolymph cause the basilar mem- brane to vibrate, which moves the hair cells of the spiral organ against the tectorial membrane. This leads to bending of the stereocilia and ultimately to the generation of nerve impulses in first-order neurons in cochlear nerve fibers. G9 Sound waves of various frequencies cause certain regions of the basilar membrane to vibrate more intensely than other regions. Each segment of the basilar membrane is “tuned” for Which part of the basilar membrane vibrates most vigorously in response to high-frequency (high-pitched) sounds? Figure 17.22 Events in the stimulation of auditory receptors in the right ear. The numbers correspond to the events listed in the text. The cochlea has been uncoiled to more easily visualize the transmission of sound waves and their distortion of the vestibular and basilar membranes of the cochlear duct. Hair cells of the spiral organ (organ of Corti) convert a mechanical vibration (stimulus) into an electrical signal (receptor potential). Scala vestibuli Cochlear duct (contains endolymph) Scala tympani Perilymph Basilar membrane Cochlea Sound waves HelicotremaStapes vibrating in oval window Malleus Incus External auditory canal Tympanic membrane Secondary tympanic membrane vibrating in round window Auditory tube Vestibular membrane Middle ear Tectorial membrane Spiral organ (organ of Corti) 1 2 3 4 5 6 8 9 7 8 Studying physiology requires an understand- ing of the sequence of processes. Correlation of sequential processes in text and art is achieved through the use of special numbered lists in the nar- rative that correspond to numbered segments in the accompanying figure. This approach is used extensively throughout the book to lend clarity to the flow of complex processes. JWCL316_fm_i-xxxiv.qxd 11/22/10 7:00 PM Page v
  • Many topics in this text have been organized into Exhibits that bring together all of the information and elements that you need to learn the complex terminology, anatomy, and the relevance of the anatomy into a simple-to-navigate content module. You will find Exhibits for tissues, bones, joints, skeletal muscles, nerves, and blood vessels. Most exhibits include the following: O B J E C T I V E • Describe the origin, insertion, action, and innervation of the extrinsic eye muscles that move the eyeballs and upper eyelids. Muscles that move the eyeballs are called extrinsic eye muscles because they originate outside the eyeballs (in the orbit) and insert on the outer surface of the sclera (“white of the eye”) (Figure 11.5). The extrinsic eye muscles are some of the fastest contracting and most precisely controlled skeletal muscles in the body. Three pairs of extrinsic eye muscles control movements of the eye- balls: (1) superior and inferior recti, (2) lateral and medial recti, and (3) superior and inferior obliques. The four recti muscles (superior, in- ferior, lateral, and medial) arise from a tendinous ring in the orbit and insert into the sclera of the eye. As their names imply, the superior and inferior recti move the eyeballs superiorly and inferiorly; the lateral and medial recti move the eyeballs laterally and medially, respectively. The actions of the oblique muscles cannot be deduced from their names. The superior oblique muscle originates posteriorly near the tendinous ring, then passes anteriorly superior to the medial rectus mus- cle, and ends in a round tendon. The tendon extends through a pulleylike loop of fibrocartilaginous tissue called the trochlea (ϭ pulley) on the an- terior and medial part of the roof of the orbit. Finally, the tendon turns and inserts on the posterolateral aspect of the eyeball. Accordingly, the supe- rior oblique muscle moves the eyeballs inferiorly and laterally. The infe- rior oblique muscle originates on the maxilla at the anteromedial aspect of the floor of the orbit. It then passes posteriorly and laterally and inserts EXHIBIT 11.B Muscles of the Head That Move the Eyeballs (Extrinsic Eye Muscles) and Upper Eyelids (Figure 11.5) on the posterolateral aspect of the eyeball. Because of this arrangement, the inferior oblique muscle moves the eyeballs superiorly and laterally. Unlike the recti and oblique muscles, the levator palpebrae superi- oris does not move the eyeballs, since its tendon passes the eyeball and inserts into the upper eyelid. Rather, it raises the upper eyelids, that is, opens the eyes. It is therefore an antagonist to the orbicularis oculi, which closes the eyes. Strabismus (stra-BIZ-mus; strabismos ϭ squinting) is a condi- tion in which the two eyeballs are not properly aligned. This can be hereditary or it can be due to birth injuries, poor attachments of the muscles, problems with the brain’s control center, or localized disease. Strabismus can be constant or intermittent. In strabismus, each eye sends an image to a different area of the brain and because the brain usually ignores the messages sent by one of the eyes, the ignored eye becomes weaker; hence “lazy eye,” or amblyopia, develops. External strabismus results when a lesion in the oculomotor (III) nerve causes the eyeball to move laterally when at rest, and results in an inability to move the eyeball medially and inferiorly. A lesion in the abducens (VI) nerve results in internal strabismus, a condition in which the eye- ball moves medially when at rest and cannot move laterally. Treatment options for strabismus depend on the specific type of problem and include surgery, visual therapy (retraining the brain’s control center), and orthoptics (eye muscle training to straighten the eyes). • CLINICAL CONNECTION | Strabismus MUSCLE ORIGIN INSERTION ACTION INNERVATION Superior rectus Common tendinous ring Superior and central part of Moves eyeballs superiorly (elevation) Oculomotor (III) nerve. (rectus ϭ fascicles (attached to orbit around eyeballs. and medially (adduction), and rotates parallel to midline) optic foramen). them medially. Inferior rectus Same as above. Inferior and central part of Moves eyeballs inferiorly (depression) Oculomotor (III) nerve. eyeballs. and medially (adduction), and rotates them medially. Lateral rectus Same as above. Lateral side of eyeballs. Moves eyeballs laterally (abduction). Abducens (VI) nerve. Medial rectus Same as above. Medial side of eyeballs. Moves eyeballs medially (adduction). Oculomotor (III) nerve. Superior oblique Sphenoid bone, superior Eyeball between superior and Moves eyeballs inferiorly (depression) Trochlear (IV) nerve. (oblique ϭ fascicles and medial to common lateral recti. Muscle inserts and laterally (abduction), and rotates diagonal to midline) tendinous ring in orbit. into superior and lateral them medially. surfaces of eyeball via tendon that passes through trochlea. Inferior oblique Maxilla in floor of orbit. Eyeballs between inferior and Moves eyeballs superiorly (elevation) Oculomotor (III) nerve. lateral recti. and laterally (abduction), and rotates them laterally. Levator palpebrae Roof of orbit (lesser Skin and tarsal plate of upper Elevates upper eyelids Oculomotor (III) nerve. superioris wing of sphenoid bone). eyelids. (opens eyes). (le-VA¯ -tor PAL-pe-bre¯ soo-perЈ-e¯ -OR-is; palpebrae ϭ eyelids) EXHIBIT 11.B CONTINUES N O T E S T O S T U D E N T S RELATING MUSCLES TO MOVEMENTS Arrange the muscles in this exhibit according to their actions on the eye- balls: (1) elevation, (2) depression, (3) abduction, (4) adduction, (5) me- dial rotation, and (6) lateral rotation. The same muscle may be men- tioned more than once. 380 EXHIBIT 11.B Trochlea SUPERIOR OBLIQUE LEVATOR PALPEBRAE SUPERIORIS (cut) SUPERIOR RECTUS INFERIOR RECTUS INFERIOR OBLIQUE LATERAL RECTUS MEDIAL RECTUS Common tendinous ring Optic (II) nerve Sphenoid bone (a) Right lateral view of right eyeball Maxilla Cornea Eyeball Frontal bone Trochlea SUPERIOR OBLIQUE (b) Movements of right eyeball in response to contraction of extrinsic muscles SUPERIOR RECTUS INFERIOR RECTUS INFERIOR OBLIQUE LATERAL RECTUS MEDIAL RECTUS Zygomatic bone (cut) INFERIOR RECTUS LATERAL RECTUS MEDIAL RECTUS SUPERIOR RECTUS Frontal bone (cut) SUPERIOR OBLIQUE LEVATOR PALPEBRAE SUPERIORIS INFERIOR OBLIQUE (c) Right lateral view of right eyeball Figure 11.5 Muscles of the head that move the eyeballs (extrinsic eye muscles) and upper eyelid. The extrinsic muscles of the eyeball are among the fastest contracting and most precisely controlled skeletal muscles in the body. How does the inferior oblique muscle move the eyeball superiorly and laterally? C H E C K P O I N T Which muscles that move the eyeballs contract and relax as you look to your left without moving your head? EXHIBIT 11.B Muscles of the Head That Move the Eyeballs (Extrinsic Eye Muscles) and Upper Eyelids (Figure 11.5) CONTINUED Exhibits Organize Complex Anatomy into Manageable Modules Objective to focus your study. Overview narrative of the structure(s). Table summarizing key features of the structure(s). Illustrations and photographs. Checkpoint Question to assess your understanding. Clinical Connection to provide relevance for learning the details. vi JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:23 Page vi
  • vii The relevance of the anatomy and physiology that you are studying is best understood when you make the con- nection between normal structure and function and what happens when the body doesn’t work the way it should. Throughout the chapters of the text you will find Clinical Connections that introduce you to interesting clinical perspectives related to the text discussion. In addition, at the end of each body system chap- ter you will find the Disorders: Homeostatic Imbalances section, which includes concise discussions of major dis- eases and disorders. These provide answers to many of your ques- tions about medical problems. The Medical Terminology section that follows includes selected terms dealing with both normal and pathological conditions. Joints that have been severely damaged by diseases such as arthritis, or by injury, may be replaced surgically with artificial joints in a procedure referred to as arthroplasty (AR-thro¯ -plas’-te¯; arthr-ϭ joint; plastyϭplastic repair of). Although most joints in the body can be repaired by arthroplasty, the ones most commonly replaced are the hips, knees, and shoulders. About 400,000 hip replacements and 300,000 knee replacements are performed annually in the United States. During the procedure, the ends of the damaged bones are re- moved and metal, ceramic, or plastic components are fixed in place. The goals of arthroplasty are to relieve pain and increase range of motion. Partial hip replacements involve only the femur. Total hip re- placements involve both the acetabulum and head of the femur (Figures A–C). The damaged portions of the acetabulum and the head of the femur are replaced by prefabricated prostheses (artificial de- vices). The acetabulum is shaped to accept the new socket, the head of the femur is removed, and the center of the femur is shaped to fit the femoral component. The acetabular component consists of a plas- CLINICAL CONNECTION | Arthroplasty tic such as polyethylene, and the femoral component is composed of a metal such as cobalt-chrome, titanium alloys, or stainless steel. These materials are designed to withstand a high degree of stress and to prevent a response by the immune system. Once the appropriate acetabular and femoral components are selected, they are attached to the healthy portion of bone with acrylic cement, which forms an interlocking mechanical bond. Knee replacements are actually a resurfacing of cartilage and, like hip replacements, may be partial or total. In a partial knee re- placement (PKR), also called a unicompartmental knee replace- ment, only one side of the knee joint is replaced. Once the damaged cartilage is removed from the distal end of the femur, the femur is re- shaped and a metal femoral component is cemented in place. Then the damaged cartilage from the proximal end of the tibia is removed, along with the meniscus. The tibia is reshaped and fitted with a plas- tic tibial component that is cemented into place. If the posterior sur- face of the patella is badly damaged, the patella is replaced with a plastic patellar component. Shaft of femur Head of femur removed Hip bone Reshaped acetabulum Artificial acetabulum Hip bone Artificial acetabulum Artificial femoral head Shaft of femur Artificial metal shaft Artificial femoral head Artificial metal shaft (A) Preparation for total hip replacement (B) Components of an artificial hip joint prior to implantation (C) Radiograph of an artificial hip joint Clinical Discussions Make Your Study Relevant N O T E S T O S T U D E N T S WileyPLUS offers you opportunities for even further Clinical Connections with animated and interactive case studies that relate specifically to one body system. Look for these under additional chapter resources as an interesting and engaging break from traditional study routines. JWCL316_fm_i-xxxiv.qxd 18/11/2010 22:16 Page vii
  • viii Your book has a variety of special fea- tures that will make your time studying anatomy and physiology a more reward- ing experience. These have been developed based on feedback from students—like you—who have used previ- ous editions of the text. Their effectiveness is even further enhanced within WileyPLUS for Anatomy and Physiology. Chapter Introductions set the stage for the content to come. Each chapter starts with a succinct overview of the particular system’s role in maintaining homeostasis in your body, followed by an introduction to the chapter content. This opening page concludes with a question that always begins with “Did you ever wonder…?” These questions will capture your interest and encourage you to find the answer in the chapter material to come. Objectives at the start of each section help you focus on what is important as you read. All of the content within WileyPLUS is tagged to these specific learning objectives so that you can organize your study or review what is still not clear in simple, more meaningful ways. Checkpoint Questions at the end of each section help you assess if you have absorbed what you have read. Take time to review these questions or answer them with- in the Practice section of each WileyPLUS concept module, N O T E S T O S T U D E N T S Chapter Resources Help You Focus and Review Mastering the Language of Anatomy and Physiology where your answers will automatically be graded to let you know where you stand. Mnemonics are a memory aid that can be particularly helpful when learning specific anatomical features. Mnemonics are included throughout the text—some dis- played in figures, tables, or Exhibits, and some included within the text discussion. We encourage you not only to use the mnemonics provided, but also to create your own to help you learn the multitude of terms involved in your study of human anatomy. Chapter Review and Resource Summary is a helpful table at the end of chapters that offers you a concise sum- mary of the important concepts from the chapter and links each section to the media resources available in WileyPLUS for Anatomy and Physiology. Self-Quiz Questions give you an opportunity to evaluate your understanding of the chapter as a whole. Within WileyPLUS, use Progress Check to quiz yourself on individual or multiple chapters in preparation for exams or quizzes. Critical Thinking Questions are word problems that allow you to apply the concepts you have studied in the chapter to specific situations. Throughout the text we have included Pronunciations and, sometimes, Word Roots for many terms that may be new to you. These appear in parentheses immediately following the new words. The pronunciations are repeated in the Glossary at the back of the book. Look at the words carefully and say them out loud several times. Learning to pronounce a new word will help you remem- ber it and make it a useful part of your medical vocabu- lary. Take a few minutes to read the Pronunciation Key, found at the beginning of the Glossary at the end of this text, so it will be familiar as you encounter new words. To provide more assistance in learning the language of anatomy, a full Glossary of terms with phonetic pronunci- ations appears at the end of the book. The basic building blocks of medical terminology—Combining Forms, Word Roots, Prefixes, and Suffixes—are listed inside the back cover, accompanied by Eponyms, traditional terms that include reference to a person’s name, along with the current terminology. WileyPLUS houses help for you in build- ing your new language skills as well. The Audio Glossary, which is always avail- able to you, lets you hear all these new, unfamiliar terms pronounced. Throughout the e-text, these terms can be clicked on and heard pronounced as you read. In addition, you can use the helpful Mastering Vocabulary program, which creates electron- ic flashcards for you of the key terms within each chapter for practice, as well as take a self-quiz specifically on the terms introduced in each chapter. JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:23 Page viii
  • ix As active teachers of the course, we recognize both the rewards and challenges in providing a strong foundation for understanding the complexities of the human body. We believe that teaching goes beyond just sharing information. How we share information makes all the difference—especially, if as we do, you have an increasingly diverse popula- tion of students with varying learning abilities. As we revised this text we focused on those areas that we knew we could enhance to provide greater impact in terms of better learning outcomes. Feedback from many of you, as well as from the students we interact with in our own classrooms, guided us in ensuring that the revisions to the text, along with the powerful new WileyPLUS for Anatomy and Physiology, support the needs and challenges you face day to day in your own classrooms. We focused on several key areas for revision: enhancing the all-important visuals, both drawings and photographs; increasing the use of Exhibits that provide a focused and functional organization of detailed content; adding some new and revising many of the tables to increase their effectiveness; updating and adding clinical material that helps students relate what they are learning to their desired career goals and the world around them; and making narrative changes aimed at increasing student engagement with—and comprehension of—the material. For a detailed list of revisions for each chapter please visit our website at and click on the text cover. N O T E S T O I N S T R U C T O R S The Art of Anatomy and Physiology Illustrations throughout the text have been refined. The color palette for the skulls in Chapter 7, and for the brain and spinal cord throughout the text, has been adjusted for greater impact. Illustrations in each chapter have been revised and updated to provide greater clarity and more saturated colors. Particular emphasis was placed on revised drawings of joints, muscles, and blood vessels. JWCL316_fm_i-xxxiv.qxd 18/11/2010 22:16 Page ix
  • N O T E S T O I N S T R U C T O R S x Cadaver photographs are included throughout the text to help students relate the content to real-life images. These are often paired with diagrams to help make the connections. Most of the meticulous dissections and outstanding photography come from Mark Nielsen’s lab at the University of Utah. Most tissue Photomicrographs have been replaced with exceptionally clear photomicrographs with high-magnification blowups. 400xLM 630xLM 630xLM 240xLM JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:23 Page x
  • xi N O T E S T O I N S T R U C T O R S The use of the pedagogically designed Exhibits has been expanded to include the axial and appendicular skeletons, as well as cranial nerves, providing students with simplified presentations of complex content. New Tables, including Skin Glands, Common Bone Fractures, Summary of the Levels of Organization within a Skeletal Muscle, and Summary of the Respiratory System, have been added, in addition to refinement of many of the existing tables with either new illustrations or rewritten text. Exhibits and Tables Your students are fascinated by the Clinical Connections to the normal anatomy and physiology that they are learning. You’ll find that the text is liberally peppered with engaging discussions of a wide variety of clinical scenarios from disease coverage to tests and procedures. As always, we have updated all of the Clinical Connections and Disorders: Homeostatic Imbalances sections to reflect the most current information. We have added several new Clinical Connections, such as a feature on fibromyalgia, to the text. A complete reference list of the Clinical Connections within each chapter follows the Table of Contents. Clinical Connections Carotid body Carotid sinus Aortic bodies Anterior GLOSSOPHARYNGEAL (IX) NERVE Posterior Inferior surface of brain Medulla oblongata VAGUS (X) NERVE Superior ganglion Small intestine Larynx Pancreas Inferior ganglion Colon Pancreas (behind stomach) Stomach Liver and gallbladder Heart Lungs EXHIBIT 14.H Vagus (X) Nerve (Figure 14.24) O B J E C T I V E • Identify the origin of the vagus nerve in the brain, the foramen through which it exits the skull, and its function. The vagus (X) nerve (VA¯-gus ϭ vagrant or wandering) is a mixed cra- nial nerve that is distributed from the head and neck into the thorax and abdomen (Figure 14.24). The nerve derives its name from its wide distri- bution. In the neck, it lies medial and posterior to the internal jugular vein and common carotid artery. Sensory axons in the vagus nerve arise from the skin of the external ear for touch, pain, and thermal sensations; a few taste buds in the epiglottis and pharynx; and proprioceptors in muscles of the neck and throat. Also, sensory axons come from baroreceptors in the carotid sinus and chemoreceptors in the carotid and aortic bodies. The majority of sensory neurons come from visceral sensory receptors in most organs of the thoracic and abdominal cavities that convey sensations (such as hunger, fullness, and discomfort) from these organs. The sensory neu- rons have cell bodies in the superior and inferior ganglia and then pass through the jugular foramen to end in the medulla and pons. The branchial motor neurons, which run briefly with the accessory nerve, arise from nuclei in the medulla oblongata and supply muscles of the pharynx, larynx, and soft palate that are used in swallowing, vocalization, and coughing. Historically these motor neurons have been called the cranial accessory nerve, but these fibers actually belong to the vagus (X) nerve. Axons of autonomic motor neurons in the vagus nerve originate in nuclei of the medulla and supply the lungs, heart, glands of the gastroin- testinal (GI) tract, and smooth muscle of the respiratory passageways, esophagus, stomach, gallbladder, small intestine, and most of the large intestine (see Figure 15.3). Autonomic motor axons initiate smooth mus- cle contractions in the gastrointestinal tract to aid motility and stimulate secretion by digestive glands; activate smooth muscle to constrict respi- ratory passageways; and decrease heart rate. C H E C K P O I N T On what basis is the vagus nerve named? Figure 14.24 Vagus (X) nerve. The vagus nerve is widely distributed in the head, neck, thorax, and abdomen. Where is the vagus nerve located in the neck region? Injury to the vagus (X) nerve due to conditions such as trauma or lesions causes vagal paralysis, or interrup- tions of sensations from many organs in the thoracic and abdominal cavi- ties; dysphagia (dis-FA¯-ge¯-a), or diffi- culty in swallowing; and tachycardia (tak’-i-KAR-de¯-a), or increased heart rate. • CLINICAL CONNECTION | Vagal Paralysis, Dysphagia, and Tachycardia Vagus (X) nerve TABLE 6.1 Some Common Fractures FRACTURE DESCRIPTION ILLUSTRATION RADIOGRAPH Open (Compound) The broken ends of the bone protrude through the skin. Conversely, a closed (simple) fracture does not break the skin. Comminuted The bone is splintered, (KOM-i-noo-ted; crushed, or broken into com- ϭ together; pieces at the site of impact, -minuted ϭ crumbled) and smaller bone fragments lie between the two main fragments. Greenstick A partial fracture in which one side of the bone is broken and the other side bends; similar to the way a green twig breaks on one side while the other side stays whole, but bends; occurs only in children, whose bones are not fully ossified and contain more organic material than inorganic material. Impacted One end of the fractured bone is forcefully driven into the interior of the other. Humerus Ulna Radius Humerus Wrist bones Radius Ulna Humerus JWCL316_fm_i-xxxiv.qxd 11/22/10 7:01 PM Page xi
  • xii N O T E S T O I N S T R U C T O R S WileyPLUS for Anatomy and Physiology is an innovative, research-based online environment designed for both effective teaching and learning. Utilizing WileyPLUS in your course provides your students with an accessible, affordable, and active learning platform and gives you tools and resources to efficiently build presentations for a dynamic classroom experience and to create and manage effective assessment strategies. The underlying principles of design, engagement, and measurable outcomes provide the foundation for this powerful, new release of WileyPLUS. DESIGN • New research-based design helps students manage their time better and develop better study skills. • Course Calendars help track assignments for both students and teachers. • New Course Plan makes it easier to assign reading, activities, and assessment. Simple drag-and-drop tools make it easy to assign the course plan as-is or in any way that best reflects your course syllabus. The new design makes it easy for students to know what it is they need to do, boosting their confidence and preparing them for greater engagement in class and lab. ENGAGEMENT • Complete online version of the textbook allows for seamless integration of all content. • Relevant student study tools and learning resources ensure positive learning outcomes. • Immediate feedback boosts confidence and helps students see a return on investment for each study session. • Precreated activities encourage learning outside of the classroom. • Course materials, including PowerPoint stacks with animations and Wiley’s Visual Library for Anatomy and Physiology, help you personalize lessons and optimize your time. Concept mastery in this discipline is directly related to students keeping up with the work and not falling behind. The new Concept Modules, Animations and Activities, Self Study, and Progress Checks in WileyPLUS will ensure that students know how to study effectively so they will remain engaged and stay on task. MEASURABLE OUTCOMES • Progress Check enables students to hone in on areas of weakness for increased success. • Self-assessment and remediation for all Learning Objectives let students know exactly how their efforts have paid off. • Instant reports monitor trends in class performance, use of course materials, and student progress toward learning objectives. With new detailed reporting capabilities, students will know that they are doing it right. With increased confi- dence, motivation is sustained so students stay on task—success will follow. Please contact your Wiley representative for details about these and other resources or visit our website at and click on the text cover to explore the assets more fully. WileyPLUS and You JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:23 Page xii
  • xiii Laboratory Manual for Anatomy and Physiology, 4e Connie Allen and Valerie Harper Newly revised, Laboratory Manual for Anatomy and Physiology with WileyPLUS 5.0 engages your students in active learning and focuses on the most important concepts in A&P. Exercises reflect the multiple ways in which students learn and provide guidance for anatomical exploration and application of critical thinking to analyzing physiological processes. A concise narrative, self-contained exercises that include a wide variety of activities and question types, and two types of lab reports for each exercise keep students focused on the task at hand. Depending on your needs, a Cat Dissection Manual or Fetal Pig Dissection Manual accompanies the main text. Rich media within WileyPLUS further enhance the student experience and include dissection videos, animations, and illustrated drill and practice exercises with illustrations, micrographs, cadaver photos, and popular lab models. Each lab text comes with access to PowerPhys 2.0. Atlas of Human Anatomy, 1e Mark Nielsen and Shawn Miller This new atlas filled with outstanding photographs of meticulously executed dissections of the human body has been developed to be a strong teaching and learning solution, not just a catalog of photographs. Organized around body systems, each chapter includes a narrative overview of the body system and is then followed with detailed photographs that accurately and realisti- cally represent the anatomical structures. Histology is included. Atlas of Human Anatomy will work well in your laboratories, as a study companion to your textbook, and as a print companion to the Real Anatomy DVD. Photographic Atlas of the Human Body, 2e Gerard J. Tortora Like the new atlas from Nielsen and Miller, this popular atlas is also systemic in its approach to the photographic review of the human body. In addition to the excellent cadaver photographs and micrographs, this atlas also contains selected cat and sheep heart dissections. The high-quality imagery can be used in the classroom, in the laboratory, or for study and review. RESOURCES FOR INTEGRATING LABORATORY EXPERIENCES JWCL316_fm_i-xxxiv.qxd 18/11/2010 20:08 Page xiii
  • xiv RESOURCES FOR INTEGRATING LABORATORY EXPERIENCES Mark Nielsen and Shawn Miller Real Anatomy is 3-D imaging software that allows you to dissect through multiple layers of a three-dimensional real human body to study and learn the anatomical structures of all body systems. Real Anatomy • Dissect through up to 40 layers of the body and discover the relationships of the structures to the whole. • Rotate the body, as well as major organs, to view the image from multiple perspectives. • Use a built-in zoom feature to get a closer look at detail. • A unique approach to highlighting and labeling structures does not obscure the real anatomy in view. JWCL316_fm_i-xxxiv.qxd 11/18/10 10:57 AM Page xiv
  • xv RESOURCES FOR INTEGRATING LABORATORY EXPERIENCES • Related images provide multiple views of structures being studied. • View histology micro- graphs at varied levels of magnification with the virtual microscope. • Snapshots of any image can be saved for use in PowerPoints, quizzes, or handouts. • Audio pronunciation of all labeled structures is readily available. Virtual Dissection—100% Real e JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xv
  • xvi RESOURCES FOR INTEGRATING LABORATORY EXPERIENCES Interactions: Exploring the Functions of the Human Body 3.0 Thomas Lancraft and Frances Frierson Interactions 3.0 is the most complete program of interactive animations and activities available for anato- my and physiology. A series of modules encompassing all body systems focuses on a review of anatomy, the examination of physiological processes using animations and interactive exercises, and clinical correlations to enhance student understanding. At the heart of Interactions is a focus on core principles— homeostasis, communication, energy flow, fluid flow, and boundaries—that underscore the key relationships between structure and function as well as interrelationships between systems. It is the reinforcement of these funda- mental organizing principles that sets this series apart from others. Interactions is available on DVD, web-based, or fully integrated within WileyPLUS. PowerPhys 2.0 Connie Allen, Valerie Harper, Thomas Lancraft, and Yuri Ivlev PowerPhys 2.0 provides a simulated laboratory experi- ence for students, giving them the opportunity to review their knowledge of core physiological concepts, predict outcomes of an experiment, collect data, ana- lyze it, and report on their findings. This revised edition features a new activity on Homeostatic Imbalance of Thyroid Function and revised lab report questions throughout. An easy-to-use and intuitive interface guides students through the experiments from basic review to laboratory reports. All experiments contain randomly generated data, allowing students to experiment multiple times but still arrive at the same conclusions. A perfect addition to distant learning or hybrid courses, PowerPhys 2.0 is a stand-alone web-based program and is fully integrated with Allen and Harper’s laboratory manual. JWCL316_fm_i-xxxiv.qxd 11/18/10 10:59 AM Page xvi
  • ACKNOWLEDGMENTS We wish to especially thank several aca- demic colleagues for their helpful contri- butions to this edition. Creating and implementing the integration of this text with WileyPLUS for Anatomy and Physiology was only possible because of the expertise and fine work of the follow- ing group of people. We are so very grateful to you: Sarah Bales Moraine Valley Community College Celina Bellanceau University of South Florida Curtis DeFriez Weber State University Alan Erickson South Dakota State University Gibril Fadika Hampton University Pamela Fouche Walters State Community College Sophia Garcia Tarrant County College–Trinity River Clare Hays Metropolitan State College of Denver Jason Hunt Brigham Young University–Idaho Judy Learn North Seattle Community College Jerri K. Lindsey Tarrant County College Todd Miller Hunter College Erin Morrey Georgia Perimeter College Gus Pita Hunter College Susan Puglisi Norwalk Community College Saeed Rahmanian Roane State Community College Lori A. Smith American River College Randall Tracy Worcester State College Jay Zimmer South Florida Community College We are also very grateful to our col- leagues who have reviewed the manu- script or participated in focus groups and offered numerous suggestions for improvement: Charles J. Biggers University of Memphis Gladys Bolding Georgia Perimeter College Lois Borek Georgia State University Betsy Brantley Lansing Community College Arthur R. Buckley University of Cincinnati Alex Cheroske Mesa Community College Robert Comegys Old Dominion University Curtis DeFriez Weber State University William Dunscombe Union County College Heather Dy Long Beach Community College Christine Ross Earls Fairfield University Angela Edwards University of South Carolina Allendale Sharon Ellerton Queensborough Community College David Evans Pennsylvania College of Technology Gibril Fadika Hampton University Sandy Garrett Texas Woman’s University Michael Harman Lone Star College Jane Horlings Saddleback College Barbara Hunnicutt Seminole State College Jason Hunt Brigham Young University–Idaho Alexander T. Imholtz Prince George’s Community College Amy E. Jetton Middle Tennessee State University Becky Keck Clemson University Marc LaBella Ocean County College Ellen Lathrop-Davis Community College of Baltimore County Billy Bob Long Del Mar College Wayne M. Mason Western Kentucky University xvii JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xvii
  • Karen McLellan Indiana Purdue University Fort Wayne Marie McMahon Miramar College Erin Morrey Georgia Perimeter College Maria Oehler Florida State College at Jacksonville Betsy Ott Tyler Junior College Gilbert Pitts Austin Peay State University Saeed Rahmanian Roane State Community College Terrence J. Ravine University of South Alabama Philip D. Reynolds Troy University John Roufaiel SUNY Rockland Community College Kelly Sexton North Lake College Colleen Sinclair Towson University Lori A. Smith American River College Nora Stevens Portland Community College Leo B. Stouder Broward College Dennis Strete McLennan Community College Peter Susan Trident Technical College Jared Taglialatela Clayton State College Bonnie J. Tarricone Ivy Tech Community College Heather Walker Clemson University Janice Webster Ivy Tech Community College Delores Wenzel University of Georgia Matthew A. Williamson Georgia Southern University Finally, our hats are off to everyone at Wiley. We enjoy collaborating with this enthusiastic, dedicated, and talented team of publish- ing professionals. Our thanks to the entire team: Bonnie Roesch, Executive Editor; Mary Berry and Karen Trost, Developmental Editors; Lorraina Raccuia, Project Editor; Lauren Morris, Program Assistant; Suzanne Ingrao, Outside Production Editor; Hilary Newman, Photo Manager; Claudia Volano, Illustration Coordinator; Anna Melhorn, Senior Illustration Editor; Madelyn Lesure, Senior Designer; Laura Ierardi, LCI Design; Linda Muriello, Senior Media Editor; and Clay Stone, Executive Marketing Manager. Gerard J. Tortora Department of Science and Health, S229 Bergen Community College 400 Paramus Road Paramus, NJ 07652 Bryan Derrickson Science Department Valencia Community College 1800 S. Kirkman Rd. Orlando, FL 32811 xviii ACKNOWLEDGMENTS JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xviii
  • ABOUT THE AUTHORS Gerard J. Tortora is Professor of Biology and former Biology Coordinator at Bergen Community College in Paramus, New Jersey, where he teaches human anatomy and physi- ology as well as microbiology. He received his bachelor’s degree in biology from Fairleigh Dickinson University and his master’s degree in science education from Montclair State College. He is a member of many professional organizations, including the Human Anatomy and Physiology Society (HAPS), American Society of Microbiology (ASM), American Association for the Advancement of Science (AAAS), National Education Association (NEA), and Metropolitan Association of College and University Biologists (MACUB). Bryan Derrickson is Professor of Biology at Valencia Community College in Orlando, Florida, where he teaches human anatomy and physiology as well as general biology and human sexuality. He received his bach- elor’s degree in biology from Morehouse College and his doctorate in cell biology from Duke University. Bryan’s study at Duke was in the Physiology Division within the Department of Cell Biology, so while his degree is in cell biology, his training focused on physiology. At Valencia, he frequently serves on faculty hiring committees. He has served as a member of the Faculty Senate, which is the governing body of the college, and as a member of the Teaching and Learning Academy, which sets the standards for the acquisi- tion of tenure by faculty members. Nationally, he is a member of To my mother, Angelina M. Tortora. (August 20, 1913–August 14, 2010). Her love, guidance, faith, support, and example continue to be the cornerstone of my personal and professional life. G.J.T. To my family: Rosalind, Hurley, Cherie, and Robb. Your support and motivation have been invaluable. B.H.D. Above all, Jerry is devoted to his students and their aspira- tions. In recognition of this commitment, Jerry was the recipient of MACUB’s 1992 President’s Memorial Award. In 1996, he received a National Institute for Staff and Organizational Development (NISOD) excellence award from the University of Texas and was selected to represent Bergen Community College in a campaign to increase awareness of the contributions of com- munity colleges to higher education. Jerry is the author of several best-selling science textbooks and laboratory manuals, a calling that often requires an additional 40 hours per week beyond his teaching responsibilities. Nevertheless, he still makes time for four or five weekly aerobic workouts that include biking and running. He also enjoys attend- ing college basketball and professional hockey games and per- formances at the Metropolitan Opera House. the Human Anatomy and Physiology Society (HAPS) and the National Association of Biology Teachers (NABT). Bryan has always wanted to teach. Inspired by several biology professors while in college, he decided to pursue physiology with an eye to teaching at the college level. He is completely dedicated to the success of his students. He particularly enjoys the chal- lenges of his diverse student population, in terms of their age, ethnicity, and academic ability, and he finds being able to reach all of them, despite their differences, a rewarding experience. His students continually recognize Bryan’s efforts and care by nomi- nating him for a campus award known as the “Valencia Professor Who Makes Valencia a Better Place to Start.” Bryan has received this award three times. xix Courtesy of Heidi Chung. JWCL316_fm_i-xxxiv.qxd 11/22/10 8:10 PM Page xix
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  • xxii CONTENTS 1 AN INTRODUCTION TO THE HUMAN BODY 1 1.1 Anatomy and Physiology Defined 2 1.2 Levels of Structural Organization and Body Systems 2 1.3 Characteristics of the Living Human Organism 5 Basic Life Processes 5 1.4 Homeostasis 8 Homeostasis and Body Fluids 8 Control of Homeostasis 9 Homeostatic Imbalances 11 1.5 Basic Anatomical Terminology 12 Body Positions 12 Regional Names 12 Directional Terms 13 Planes and Sections 16 Body Cavities 17 Abdominopelvic Regions and Quadrants 19 1.6 Medical Imaging 21 Chapter Review and Resource Summary 25 / Self-Quiz Questions 27 / Critical Thinking Questions 28 / Answers to Figure Questions 28 2 THE CHEMICAL LEVEL OF ORGANIZATION 29 2.1 How Matter Is Organized 30 Chemical Elements 30 Structure of Atoms 31 Atomic Number and Mass Number 31 Atomic Mass 32 Ions, Molecules, and Compounds 32 2.2 Chemical Bonds 33 Ionic Bonds 33 Covalent Bonds 35 Hydrogen Bonds 36 2.3 Chemical Reactions 37 Forms of Energy and Chemical Reactions 37 Energy Transfer in Chemical Reactions 37 Types of Chemical Reactions 38 2.4 Inorganic Compounds and Solutions 40 Water 40 Solutions, Colloids, and Suspensions 41 Inorganic Acids, Bases, and Salts 42 Acid–Base Balance: The Concept of pH 42 Maintaining pH: Buffer Systems 42 2.5 Organic Compounds 44 Carbon and Its Functional Groups 44 Carbohydrates 45 Lipids 47 Proteins 51 Nucleic Acids: Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA) 56 Adenosine Triphosphate 56 Chapter Review and Resource Summary 58 / Self-Quiz Questions 60 / Critical Thinking Questions 61 / Answers to Figure Questions 61 3 THE CELLULAR LEVEL OF ORGANIZATION 63 3.1 Parts of a Cell 64 3.2 The Plasma Membrane 65 Structure of the Plasma Membrane 65 Functions of Membrane Proteins 66 Membrane Fluidity 66 Membrane Permeability 67 Gradients across the Plasma Membrane 68 3.3 Transport across the Plasma Membrane 68 Passive Processes 68 Active Processes 73 3.4 Cytoplasm 78 Cytosol 78 Organelles 81 3.5 Nucleus 88 3.6 Protein Synthesis 92 Transcription 92 Translation 94 3.7 Cell Division 94 Somatic Cell Division 96 Control of Cell Destiny 99 Reproductive Cell Division 100 3.8 Cellular Diversity 103 3.9 Aging and Cells 103 Medical Terminology 106 / Chapter Review and Resource Summary 106 / Self-Quiz Questions 110 / Critical Thinking Questions 112 / Answers to Figure Questions 112 4 THE TISSUE LEVEL OF ORGANIZATION 113 4.1 Types of Tissues 114 JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxii
  • 4.2 Cell Junctions 114 Tight Junctions 115 Adherens Junctions 115 Desmosomes 116 Hemidesmosomes 116 Gap Junctions 116 4.3 Comparison between Epithelial and Connective Tissues 116 4.4 Epithelial Tissues 116 Classification of Epithelial Tissues 118 Covering and Lining Epithelium 119 Glandular Epithelium 126 4.5 Connective Tissues 128 General Features of Connective Tissues 128 Connective Tissue Cells 128 Connective Tissue Extracellular Matrix 130 Classification of Connective Tissues 131 Embryonic Connective Tissues 132 Mature Connective Tissues 133 4.6 Membranes 139 Epithelial Membranes 140 Synovial Membranes 142 4.7 Muscular Tissues 143 4.8 Nervous Tissue 143 4.9 Excitable Cells 144 4.10 Tissue Repair: Restoring Homeostasis 145 4.11 Aging and Tissues 146 Medical Terminology 147 / Chapter Review and Resource Summary 147 / Self-Quiz Questions 151 / Critical Thinking Questions 152 / Answers to Figure Questions 152 5 THE INTEGUMENTARY SYSTEM 153 5.1 Structure of the Skin 154 Epidermis 155 Keratinization and Growth of the Epidermis 158 Dermis 159 The Structural Basis of Skin Color 160 Tattooing and Body Piercing 161 5.2 Accessory Structures of the Skin 161 Hair 161 Skin Glands 164 Nails 165 5.3 Types of Skin 167 5.4 Functions of the Skin 167 Thermoregulation 167 Blood Reservoir 168 Protection 168 Cutaneous Sensations 168 Excretion and Absorption 168 Synthesis of Vitamin D 168 5.5 Maintaining Homeostasis: Skin Wound Healing 169 Epidermal Wound Healing 169 Deep Wound Healing 169 5.6 Development of the Integumentary System 170 5.7 Aging and the Integumentary System 172 Medical Terminology 177 / Chapter Review and Resource Summary 178 / Self-Quiz Questions 180 / Critical Thinking Questions 181 / Answers to Figure Questions 181 6 THE SKELETAL SYSTEM: BONE TISSUE 182 6.1 Functions of Bone and the Skeletal System 183 6.2 Structure of Bone 183 6.3 Histology of Bone Tissue 184 Compact Bone Tissue 186 Spongy Bone Tissue 186 6.4 Blood and Nerve Supply of Bone 188 6.5 Bone Formation 189 Initial Bone Formation in an Embryo and Fetus 189 Bone Growth during Infancy, Childhood, and Adolescence 192 Remodeling of Bone 194 Factors Affecting Bone Growth and Bone Remodeling 196 6.6 Fracture and Repair of Bone 196 6.7 Bone’s Role in Calcium Homeostasis 200 6.8 Exercise and Bone Tissue 201 6.9 Aging and Bone Tissue 201 Medical Terminology 203 / Chapter Review and Resource Summary 204 / Self-Quiz Questions 205 / Critical Thinking Questions 207 / Answers to Figure Questions 207 7 THE SKELETAL SYSTEM: THE AXIAL SKELETON 208 7.1 Divisions of the Skeletal System 209 7.2 Types of Bones 209 7.3 Bone Surface Markings 211 7.4 Skull 212 General Features and Functions 227 Nasal Septum 227 Orbits 228 Foramina 228 Unique Features of the Skull 229 7.5 Hyoid Bone 232 7.6 Vertebral Column 233 Normal Curves of the Vertebral Column 234 Intervertebral Discs 234 Parts of a Typical Vertebra 235 Regions of the Vertebral Column 236 Age-Related Changes in the Vertebral Column 236 CONTENTS xxiii JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxiii
  • 7.7 Thorax 236 Medical Terminology 250 / Chapter Review and Resource Summary 251 / Self-Quiz Questions 252 / Critical Thinking Questions 254 / Answers to Figure Questions 254 8 THE SKELETAL SYSTEM: THE APPENDICULAR SKELETON 255 8.1 Pectoral (Shoulder) Girdle 256 8.2 Upper Limb (Extremity) 260 8.3 Pelvic (Hip) Girdle 267 8.4 False and True Pelves 270 8.5 Comparison of Female and Male Pelves 271 8.6 Lower Limb (Extremity) 273 8.7 Development of the Skeletal System 282 Medical Terminology 285 / Chapter Review and Resource Summary 285 / Self-Quiz Questions 286 / Critical Thinking Questions 288 / Answers to Figure Questions 288 9 JOINTS 289 9.1 Joint Classifications 290 9.2 Fibrous Joints 290 Sutures 290 Syndesmoses 291 Interosseous Membranes 291 9.3 Cartilaginous Joints 292 Synchondroses 292 Symphyses 292 9.4 Synovial Joints 292 Structure of Synovial Joints 292 Nerve and Blood Supply 295 Bursae and Tendon Sheaths 295 9.5 Types of Movements at Synovial Joints 296 Gliding 296 Angular Movements 296 Rotation 299 Special Movements 300 9.6 Types of Synovial Joints 302 Plane Joints 302 Hinge Joints 302 Pivot Joints 302 Condyloid Joints 302 Saddle Joints 302 Ball-and-Socket Joints 302 9.7 Factors Affecting Contact and Range of Motion at Synovial Joints 305 9.8 Selected Joints of the Body 305 9.9 Aging and Joints 320 9.10 Arthroplasty 320 Hip Replacements 320 Knee Replacements 320 Medical Terminology 322 / Chapter Review and Resource Summary 323 / Self-Quiz Questions 325 / Critical Thinking Questions 326 / Answers to Figure Questions 326 10 MUSCULAR TISSUE 327 10.1 Overview of Muscular Tissue 328 Types of Muscular Tissue 328 Functions of Muscular Tissue 328 Properties of Muscular Tissue 328 10.2 Skeletal Muscle Tissue 329 Connective Tissue Components 329 Nerve and Blood Supply 331 Microscopic Anatomy of a Skeletal Muscle Fiber 331 Muscle Proteins 335 10.3 Contraction and Relaxation of Skeletal Muscle Fibers 338 The Sliding Filament Mechanism 338 The Neuromuscular Junction 341 10.4 Muscle Metabolism 345 Production of ATP in Muscle Fibers 345 Muscle Fatigue 347 Oxygen Consumption after Exercise 347 10.5 Control of Muscle Tension 347 Motor Units 347 Twitch Contraction 348 Frequency of Stimulation 348 Motor Unit Recruitment 349 Muscle Tone 350 Isotonic and Isometric Contractions 350 10.6 Types of Skeletal Muscle Fibers 351 Slow Oxidative Fibers 351 Fast Oxidative–Glycolytic Fibers 351 Fast Glycolytic Fibers 352 Distribution and Recruitment of Different Types of Fibers 352 10.7 Exercise and Skeletal Muscle Tissue 352 Effective Stretching 352 Strength Training 353 10.8 Cardiac Muscle Tissue 354 10.9 Smooth Muscle Tissue 354 Microscopic Anatomy of Smooth Muscle 355 Physiology of Smooth Muscle 355 10.10 Regeneration of Muscular Tissue 356 10.11 Development of Muscle 356 10.12 Aging and Muscular Tissue 358 Medical Terminology 360 / Chapter Review and Resource Summary 360 / Self-Quiz Questions 363 / Critical Thinking Questions 365 / Answers to Figure Questions 365 xxiv CONTENTS JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxiv
  • 11 THE MUSCULAR SYSTEM 366 11.1 How Skeletal Muscles Produce Movements 367 Muscle Attachment Sites: Origin and Insertion 367 Lever Systems and Leverage 368 Effects of Fascicle Arrangement 368 Coordination among Muscles 369 11.2 How Skeletal Muscles Are Named 371 11.3 Principal Skeletal Muscles 371 Medical Terminology 442 / Chapter Review and Resource Summary 443 / Self-Quiz Questions 444 / Critical Thinking Questions 446 / Answers to Figure Questions 446 12 NERVOUS TISSUE 447 12.1 Overview of the Nervous System 448 Organization of the Nervous System 448 Functions of the Nervous System 448 12.2 Histology of Nervous Tissue 450 Neurons 450 Neuroglia 454 Myelination 456 Collections of Nervous Tissue 457 12.3 Electrical Signals in Neurons 458 Ion Channels 460 Resting Membrane Potential 462 Graded Potentials 464 Generation of Action Potentials 466 Propagation of Action Potentials 470 Encoding of Stimulus Intensity 472 Comparison of Electrical Signals Produced by Excitable Cells 472 12.4 Signal Transmission at Synapses 473 Electrical Synapses 473 Chemical Synapses 473 Excitatory and Inhibitory Postsynaptic Potentials 475 Structure of Neurotransmitter Receptors 475 Removal of Neurotransmitter 475 Spatial and Temporal Summation of Postsynaptic Potentials 477 12.5 Neurotransmitters 480 Small-Molecule Neurotransmitters 480 Neuropeptides 482 12.6 Neural Circuits 483 12.7 Regeneration and Repair of Nervous Tissue 484 Neurogenesis in the CNS 485 Damage and Repair in the PNS 485 Medical Terminology 486 / Chapter Review and Resource Summary 487 / Self-Quiz Questions 489 / Critical Thinking Questions 491 / Answers to Figure Questions 491 13 THE SPINAL CORD AND SPINAL NERVES 492 13.1 Spinal Cord Anatomy 493 Protective Structures 493 Vertebral Column 493 External Anatomy of the Spinal Cord 493 Internal Anatomy of the Spinal Cord 498 13.2 Spinal Nerves 500 Connective Tissue Coverings of Spinal Nerves 501 Distribution of Spinal Nerves 501 Dermatomes 512 13.3 Spinal Cord Physiology 512 Sensory and Motor Tracts 512 Reflexes and Reflex Arcs 514 Medical Terminology 522 / Chapter Review and Resource Summary 523 / Self-Quiz Questions 524 / Critical Thinking Questions 526 / Answers to Figure Questions 526 14 THE BRAIN AND CRANIAL NERVES 527 14.1 Brain Organization, Protection, and Blood Supply 528 Major Parts of the Brain 528 Protective Coverings of the Brain 528 Brain Blood Flow and the Blood–Brain Barrier 531 14.2 Cerebrospinal Fluid 531 Functions of CSF 531 Formation of CSF in the Ventricles 532 Circulation of CSF 532 14.3 The Brain Stem and Reticular Formation 536 Medulla Oblongata 536 Pons 538 Midbrain 538 Reticular Formation 540 14.4 The Cerebellum 541 14.5 The Diencephalon 543 Thalamus 543 Hypothalamus 544 Epithalamus 546 Circumventricular Organs 546 14.6 The Cerebrum 546 Cerebral Cortex 546 Lobes of the Cerebrum 549 Cerebral White Matter 549 Basal Nuclei 549 The Limbic System 549 CONTENTS xxv JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxv
  • 14.7 Functional Organization of the Cerebral Cortex 552 Sensory Areas 553 Motor Areas 553 Association Areas 553 Hemispheric Lateralization 556 Brain Waves 556 14.8 Cranial Nerves 557 14.9 Development of the Nervous System 571 14.10 Aging and the Nervous System 573 Medical Terminology 574 / Chapter Review and Resource Summary 575 / Self-Quiz Questions 577 / Critical Thinking Questions 579 / Answers to Figure Questions 579 15 THE AUTONOMIC NERVOUS SYSTEM 581 15.1 Comparison of Somatic and Autonomic Nervous Systems 582 Somatic Nervous System 582 Autonomic Nervous System 582 Comparison of Somatic and Autonomic Motor Neurons 582 15.2 Anatomy of Autonomic Motor Pathways 584 Anatomical Components 584 Structure of the Sympathetic Division 590 Structure of the Parasympathetic Division 591 Structure of the Enteric Division 593 15.3 ANS Neurotransmitters and Receptors 593 Cholinergic Neurons and Receptors 593 Adrenergic Neurons and Receptors 594 Receptor Agonists and Antagonists 594 15.4 Physiology of the ANS 596 Autonomic Tone 596 Sympathetic Responses 596 Parasympathetic Responses 596 15.5 Integration and Control of Autonomic Functions 599 Autonomic Reflexes 599 Autonomic Control by Higher Centers 601 Medical Terminology 602 / Chapter Review and Resource Summary 602 / Self-Quiz Questions 603 / Critical Thinking Questions 605 / Answers to Figure Questions 605 16 SENSORY, MOTOR, AND INTEGRATIVE SYSTEMS 606 16.1 Sensation 607 Sensory Modalities 607 The Process of Sensation 607 Sensory Receptors 607 16.2 Somatic Sensations 610 Tactile Sensations 610 Thermal Sensations 611 Pain Sensations 611 Proprioceptive Sensations 613 16.3 Somatic Sensory Pathways 615 Posterior Column–Medial Lemniscus Pathway to the Cortex 616 Anterolateral Pathway to the Cortex 616 Trigeminothalamic Pathway to the Cortex 617 Mapping the Primary Somatosensory Area 618 Somatic Sensory Pathways to the Cerebellum 619 16.4 Somatic Motor Pathways 620 Organization of Upper Motor Neuron Pathways 621 Roles of the Basal Nuclei 625 Modulation of Movement by the Cerebellum 625 16.5 Integrative Functions of the Cerebrum 627 Wakefulness and Sleep 627 Learning and Memory 628 Medical Terminology 630 / Chapter Review and Resource Summary 631 / Self-Quiz Questions 632 / Critical Thinking Questions 634 / Answers to Figure Questions 634 17 THE SPECIAL SENSES 635 17.1 Olfaction: Sense of Smell 636 Anatomy of Olfactory Receptors 636 Physiology of Olfaction 637 Odor Thresholds and Adaptation 638 The Olfactory Pathway 638 17.2 Gustation: Sense of Taste 639 Anatomy of Taste Buds and Papillae 639 Physiology of Gustation 639 Taste Thresholds and Adaptation 641 The Gustatory Pathway 641 17.3 Vision 642 Electromagnetic Radiation 642 Accessory Structures of the Eye 642 Anatomy of the Eyeball 646 Image Formation 649 Convergence 653 Physiology of Vision 653 The Visual Pathway 655 17.4 Hearing and Equilibrium 656 Anatomy of the Ear 658 The Nature of Sound Waves 661 Physiology of Hearing 664 The Auditory Pathway 665 Physiology of Equilibrium 665 Equilibrium Pathways 669 xxvi CONTENTS JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxvi
  • 17.5 Development of the Eyes and Ears 671 Eyes 671 Ears 671 17.6 Aging and the Special Senses 673 Medical Terminology 675 / Chapter Review and Resource Summary 675 / Self-Quiz Questions 677 / Critical Thinking Questions 679 / Answers to Figure Questions 679 18 THE ENDOCRINE SYSTEM 680 18.1 Comparison of Control by the Nervous and Endocrine Systems 681 18.2 Endocrine Glands 681 18.3 Hormone Activity 682 The Role of Hormone Receptors 682 Circulating and Local Hormones 683 Chemical Classes of Hormones 684 Hormone Transport in the Blood 684 18.4 Mechanisms of Hormone Action 684 Action of Lipid-Soluble Hormones 686 Action of Water-Soluble Hormones 686 Hormone Interactions 687 18.5 Control of Hormone Secretion 688 18.6 Hypothalamus and Pituitary Gland 688 Anterior Pituitary 688 Posterior Pituitary 694 18.7 Thyroid Gland 696 Formation, Storage, and Release of Thyroid Hormones 696 Actions of Thyroid Hormones 698 Control of Thyroid Hormone Secretion 699 Calcitonin 699 18.8 Parathyroid Glands 700 Parathyroid Hormone 700 18.9 Adrenal Glands 703 Adrenal Cortex 703 Adrenal Medulla 706 18.10 Pancreatic Islets 707 Cell Types in the Pancreatic Islets 709 Regulation of Glucagon and Insulin Secretion 709 18.11 Ovaries and Testes 711 18.12 Pineal Gland and Thymus 711 18.13 Other Endocrine Tissues and Organs, Eicosanoids, and Growth Factors 712 Hormones from Other Endocrine Tissues and Organs 712 Eicosanoids 712 Growth Factors 713 18.14 The Stress Response 713 The Fight-or-Flight Response 713 The Resistance Reaction 714 Exhaustion 714 Stress and Disease 714 18.15 Development of the Endocrine System 716 18.16 Aging and the Endocrine System 717 Medical Terminology 721 / Chapter Review and Resource Summary 722 / Self-Quiz Questions 725 / Critical Thinking Questions 727 / Answers to Figure Questions 727 19 THE CARDIOVASCULAR SYSTEM: THE BLOOD 728 19.1 Functions and Properties of Blood 729 Functions of Blood 729 Physical Characteristics of Blood 729 Components of Blood 729 19.2 Formation of Blood Cells 732 19.3 Red Blood Cells 735 RBC Anatomy 735 RBC Physiology 735 19.4 White Blood Cells 738 Types of WBCs 738 Functions of WBCs 739 19.5 Platelets 741 19.6 Stem Cell Transplants from Bone Marrow and Cord Blood 743 19.7 Hemostasis 743 Vascular Spasm 743 Platelet Plug Formation 743 Blood Clotting 744 Role of Vitamin K in Clotting 746 Hemostatic Control Mechanisms 746 Intravascular Clotting 747 19.8 Blood Groups and Blood Types 748 ABO Blood Group 748 Transfusions 749 Rh Blood Group 749 Typing and Cross-Matching Blood for Transfusion 750 Medical Terminology 752 / Chapter Review and Resource Summary 753 / Self-Quiz Questions 755 / Critical Thinking Questions 756 / Answers to Figure Questions 756 20 THE CARDIOVASCULAR SYSTEM: THE HEART 757 20.1 Anatomy of the Heart 758 Location of the Heart 758 Pericardium 758 Layers of the Heart Wall 760 Chambers of the Heart 761 Myocardial Thickness and Function 765 Fibrous Skeleton of the Heart 765 CONTENTS xxvii JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxvii
  • 20.2 Heart Valves and Circulation of Blood 766 Operation of the Atrioventricular Valves 767 Operation of the Semilunar Valves 767 Systemic and Pulmonary Circulations 768 Coronary Circulation 768 20.3 Cardiac Muscle Tissue and the Cardiac Conduction System 772 Histology of Cardiac Muscle Tissue 772 Autorhythmic Fibers: The Conduction System 772 Action Potential and Contraction of Contractile Fibers 775 ATP Production in Cardiac Muscle 776 Electrocardiogram 776 Correlation of ECG Waves with Atrial and Ventricular Systole 777 20.4 The Cardiac Cycle 779 Pressure and Volume Changes during the Cardiac Cycle 779 Heart Sounds 781 20.5 Cardiac Output 782 Regulation of Stroke Volume 782 Regulation of Heart Rate 783 20.6 Exercise and the Heart 786 20.7 Help for Failing Hearts 786 20.8 Development of the Heart 789 Medical Terminology 796 / Chapter Review and Resource Summary 797 / Self-Quiz Questions 799 / Critical Thinking Questions 801 / Answers to Figure Questions 801 21 THE CARDIOVASCULAR SYSTEM: BLOOD VESSELS AND HEMODYNAMICS 802 21.1 Structure and Function of Blood Vessels 803 Basic Structure of a Blood Vessel 803 Arteries 805 Anastomoses 806 Arterioles 806 Capillaries 806 Venules 808 Veins 809 Blood Distribution 811 21.2 Capillary Exchange 811 Diffusion 811 Transcytosis 812 Bulk Flow: Filtration and Reabsorption 812 21.3 Hemodynamics: Factors Affecting Blood Flow 814 Blood Pressure 814 Vascular Resistance 815 Venous Return 815 Velocity of Blood Flow 816 21.4 Control of Blood Pressure and Blood Flow 817 Role of the Cardiovascular Center 817 Neural Regulation of Blood Pressure 819 Hormonal Regulation of Blood Pressure 820 Autoregulation of Blood Pressure 821 21.5 Checking Circulation 822 Pulse 822 Measuring Blood Pressure 822 21.6 Shock and Homeostasis 823 Types of Shock 823 Homeostatic Responses to Shock 824 Signs and Symptoms of Shock 824 21.7 Circulatory Routes 824 The Systemic Circulation 826 The Hepatic Portal Circulation 861 The Pulmonary Circulation 862 The Fetal Circulation 862 21.8 Development of Blood Vessels and Blood 865 21.9 Aging and the Cardiovascular System 866 Medical Terminology 869 / Chapter Review and Resource Summary 869 / Self-Quiz Questions 871 / Critical Thinking Questions 873 / Answers to Figure Questions 873 22 THE LYMPHATIC SYSTEM AND IMMUNITY 875 22.1 Lymphatic System Structure and Function 876 Functions of the Lymphatic System 876 Lymphatic Vessels and Lymph Circulation 876 Lymphatic Organs and Tissues 880 22.2 Development of Lymphatic Tissues 886 22.3 Innate Immunity 886 First Line of Defense: Skin and Mucous Membranes 886 Second Line of Defense: Internal Defenses 887 22.4 Adaptive Immunity 890 Maturation of T Cells and B Cells 890 Types of Adaptive Immunity 891 Clonal Selection: The Principle 891 Antigens and Antigen Receptors 893 Major Histocompatibility Complex Antigens 894 Pathways of Antigen Processing 894 Cytokines 896 22.5 Cell-Mediated Immunity 896 Activation of T Cells 897 Activation and Clonal Selection of Helper T Cells 897 Activation and Clonal Selection of Cytotoxic T Cells 898 Elimination of Invaders 898 Immunological Surveillance 899 22.6 Antibody-Mediated Immunity 900 Activation and Clonal Selection of B Cells 900 Antibodies 900 Immunological Memory 905 xxviii CONTENTS JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxviii
  • 22.7 Self-Recognition and Self-Tolerance 906 22.8 Stress and Immunity 908 22.9 Aging and the Immune System 908 Medical Terminology 912 / Chapter Review and Resource Summary 913 / Self-Quiz Questions 915 / Critical Thinking Questions 917 / Answers to Figure Questions 917 23 THE RESPIRATORY SYSTEM 918 23.1 Respiratory System Anatomy 919 Nose 919 Pharynx 922 Larynx 923 The Structures of Voice Production 925 Trachea 927 Bronchi 928 Lungs 929 Patency of the Respiratory System 934 23.2 Pulmonary Ventilation 936 Pressure Changes during Pulmonary Ventilation 936 Other Factors Affecting Pulmonary Ventilation 939 Breathing Patterns and Modified Respiratory Movements 940 23.3 Lung Volumes and Capacities 941 23.4 Exchange of Oxygen and Carbon Dioxide 943 Gas Laws: Dalton’s Law and Henry’s Law 943 External and Internal Respiration 944 23.5 Transport of Oxygen and Carbon Dioxide 946 Oxygen Transport 946 Carbon Dioxide Transport 950 Summary of Gas Exchange and Transport in Lungs and Tissues 950 23.6 Control of Respiration 951 Respiratory Center 951 Regulation of the Respiratory Center 953 23.7 Exercise and the Respiratory System 955 23.8 Development of the Respiratory System 956 23.9 Aging and the Respiratory System 959 Medical Terminology 961 / Chapter Review and Resource Summary 962 / Self-Quiz Questions 964 / Critical Thinking Questions 966 / Answers to Figure Questions 966 24 THE DIGESTIVE SYSTEM 967 24.1 Overview of the Digestive System 968 24.2 Layers of the GI Tract 969 Mucosa 969 Submucosa 970 Muscularis 970 Serosa 970 24.3 Neural Innervation of the GI Tract 971 Enteric Nervous System 971 Autonomic Nervous System 971 Gastrointestinal Reflex Pathways 971 24.4 Peritoneum 972 24.5 Mouth 974 Salivary Glands 974 Tongue 977 Teeth 977 Mechanical and Chemical Digestion in the Mouth 978 24.6 Pharynx 980 24.7 Esophagus 980 Histology of the Esophagus 980 Physiology of the Esophagus 981 24.8 Deglutition 981 24.9 Stomach 982 Anatomy of the Stomach 982 Histology of the Stomach 984 Mechanical and Chemical Digestion in the Stomach 986 24.10 Pancreas 988 Anatomy of the Pancreas 988 Histology of the Pancreas 988 Composition and Functions of Pancreatic Juice 988 24.11 Liver and Gallbladder 990 Anatomy of the Liver and Gallbladder 990 Histology of the Liver and Gallbladder 991 Blood Supply of the Liver 993 Functions of the Liver and Gallbladder 994 24.12 Small Intestine 995 Anatomy of the Small Intestine 995 Histology of the Small Intestine 995 Role of Intestinal Juice and Brush-Border Enzymes 998 Mechanical Digestion in the Small Intestine 998 Chemical Digestion in the Small Intestine 1000 Absorption in the Small Intestine 1001 24.13 Large Intestine 1006 Anatomy of the Large Intestine 1006 Histology of the Large Intestine 1006 Mechanical Digestion in the Large Intestine 1009 Chemical Digestion in the Large Intestine 1009 Absorption and Feces Formation in the Large Intestine 1010 The Defecation Reflex 1010 24.14 Phases of Digestion 1011 Cephalic Phase 1011 Gastric Phase 1012 Intestinal Phase 1012 Other Hormones of the Digestive System 1013 24.15 Development of the Digestive System 1014 CONTENTS xxix JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxix
  • 24.16 Aging and the Digestive System 1014 Medical Terminology 1017 / Chapter Review and Resource Summary 1018 / Self-Quiz Questions 1021 / Critical Thinking Questions 1023 / Answers to Figure Questions 1023 25 METABOLISM AND NUTRITION 1024 25.1 Metabolic Reactions 1025 Coupling of Catabolism and Anabolism by ATP 1025 25.2 Energy Transfer 1026 Oxidation–Reduction Reactions 1026 Mechanisms of ATP Generation 1026 25.3 Carbohydrate Metabolism 1027 The Fate of Glucose 1027 Glucose Movement into Cells 1027 Glucose Catabolism 1027 Glucose Anabolism 1034 25.4 Lipid Metabolism 1037 Transport of Lipids by Lipoproteins 1037 Sources and Significance of Blood Cholesterol 1038 The Fate of Lipids 1038 Triglyceride Storage 1038 Lipid Catabolism: Lipolysis 1038 Lipid Anabolism: Lipogenesis 1039 25.5 Protein Metabolism 1040 The Fate of Proteins 1040 Protein Catabolism 1040 Protein Anabolism 1040 25.6 Key Molecules at Metabolic Crossroads 1042 The Role of Glucose 6-Phosphate 1043 The Role of Pyruvic Acid 1043 The Role of Acetyl Coenzyme A 1043 25.7 Metabolic Adaptations 1043 Metabolism during the Absorptive State 1044 Metabolism during the Postabsorptive State 1046 Metabolism during Fasting and Starvation 1047 25.8 Heat and Energy Balance 1048 Metabolic Rate 1048 Body Temperature Homeostasis 1048 Energy Homeostasis and Regulation of Food Intake 1051 25.9 Nutrition 1052 Guidelines for Healthy Eating 1053 Minerals 1054 Vitamins 1054 Medical Terminology 1059 / Chapter Review and Resource Summary 1059 / Self-Quiz Questions 1062 / Critical Thinking Questions 1064 / Answers to Figure Questions 1064 26 THE URINARY SYSTEM 1065 26.1 Overview of Kidney Functions 1067 26.2 Anatomy and Histology of the Kidneys 1067 External Anatomy of the Kidneys 1067 Internal Anatomy of the Kidneys 1069 Blood and Nerve Supply of the Kidneys 1069 The Nephron 1071 26.3 Overview of Renal Physiology 1076 26.4 Glomerular Filtration 1077 The Filtration Membrane 1077 Net Filtration Pressure 1078 Glomerular Filtration Rate 1079 26.5 Tubular Reabsorption and Tubular Secretion 1081 Principles of Tubular Reabsorption and Secretion 1081 Reabsorption and Secretion in the Proximal Convoluted Tubule 1083 Reabsorption in the Loop of Henle 1085 Reabsorption in the Early Distal Convoluted Tubule 1086 Reabsorption and Secretion in the Late Distal Convoluted Tubule and Collecting Duct 1086 Hormonal Regulation of Tubular Reabsorption and Tubular Secretion 1087 26.6 Production of Dilute and Concentrated Urine 1088 Formation of Dilute Urine 1089 Formation of Concentrated Urine 1089 26.7 Evaluation of Kidney Function 1092 Urinalysis 1092 Blood Tests 1094 Renal Plasma Clearance 1094 26.8 Urine Transportation, Storage, and Elimination 1096 Ureters 1096 Urinary Bladder 1097 Urethra 1099 26.9 Waste Management in Other Body Systems 1100 26.10 Development of the Urinary System 1100 26.11 Aging and the Urinary System 1103 Medical Terminology 1104 / Chapter Review and Resource Summary 1105 / Self-Quiz Questions 1107 / Critical Thinking Questions 1109 / Answers to Figure Questions 1109 27 FLUID, ELECTROLYTE, AND ACID–BASE HOMEOSTASIS 1110 27.1 Fluid Compartments and Fluid Balance 1111 Sources of Body Water Gain and Loss 1112 Regulation of Body Water Gain 1112 Regulation of Water and Solute Loss 1112 Movement of Water between Body Fluid Compartments 1114 xxx CONTENTS JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxx
  • 27.2 Electrolytes in Body Fluids 1115 Concentrations of Electrolytes in Body Fluids 1115 Sodium 1116 Chloride 1117 Potassium 1117 Bicarbonate 1117 Calcium 1117 Phosphate 1117 Magnesium 1118 27.3 Acid–Base Balance 1118 The Actions of Buffer Systems 1120 Exhalation of Carbon Dioxide 1121 Kidney Excretion of Hϩ 1122 Acid–Base Imbalances 1123 27.4 Aging and Fluid, Electrolyte, and Acid–Base Balance 1124 Chapter Review and Resource Summary 1125 / Self-Quiz Questions 1127 / Critical Thinking Questions 1128 / Answers to Figure Questions 1128 28 THE REPRODUCTIVE SYSTEMS 1129 28.1 Male Reproductive System 1130 Scrotum 1130 Testes 1131 Reproductive System Ducts in Males 1138 Accessory Sex Glands 1140 Semen 1141 Penis 1141 28.2 Female Reproductive System 1143 Ovaries 1143 Uterine Tubes 1149 Uterus 1151 Vagina 1155 Vulva 1157 Perineum 1158 Mammary Glands 1158 28.3 The Female Reproductive Cycle 1160 Hormonal Regulation of the Female Reproductive Cycle 1160 Phases of the Female Reproductive Cycle 1161 28.4 Birth Control Methods and Abortion 1165 Birth Control Methods 1165 Abortion 1167 28.5 Development of the Reproductive Systems 1167 28.6 Aging and the Reproductive Systems 1170 Medical Terminology 1174 / Chapter Review and Resource Summary 1175 / Self-Quiz Questions 1178 / Critical Thinking Questions 1180 / Answers to Figure Questions 1180 29 DEVELOPMENT AND INHERITANCE 1181 29.1 Embryonic Period 1182 First Week of Development 1182 Second Week of Development 1186 Third Week of Development 1188 Fourth Week of Development 1195 Fifth through Eighth Weeks of Development 1197 29.2 Fetal Period 1198 29.3 Teratogens 1201 Chemicals and Drugs 1201 Cigarette Smoking 1201 Irradiation 1201 29.4 Prenatal Diagnostic Tests 1201 Fetal Ultrasonography 1201 Amniocentesis 1201 Chorionic Villi Sampling 1202 Noninvasive Prenatal Tests 1202 29.5 Maternal Changes during Pregnancy 1203 Hormones of Pregnancy 1203 Changes during Pregnancy 1205 29.6 Exercise and Pregnancy 1206 29.7 Labor 1206 29.8 Adjustments of the Infant at Birth 1208 Respiratory Adjustments 1208 Cardiovascular Adjustments 1208 29.9 The Physiology of Lactation 1209 29.10 Inheritance 1210 Genotype and Phenotype 1211 Variations on Dominant–Recessive Inheritance 1212 Autosomes, Sex Chromosomes, and Sex Determination 1214 Sex-Linked Inheritance 1215 Medical Terminology 1217 / Chapter Review and Resource Summary 1217 / Self-Quiz Questions 1220 / Critical Thinking Questions 1222 / Answers to Figure Questions 1222 APPENDIX A: MEASUREMENTS A-1 APPENDIX B: PERIODIC TABLE B-3 APPENDIX C: NORMAL VALUES FOR SELECTED BLOOD TESTS C-4 APPENDIX D: NORMAL VALUES FOR SELECTED URINE TESTS D-6 APPENDIX E: ANSWERS E-8 GLOSSARY G-1 CREDITS C-1 INDEX I-1 CONTENTS xxxi JWCL316_fm_i-xxxiv.qxd 11/18/10 10:59 AM Page xxxi
  • CLINICAL CONNECTIONS AND DISORDERS CHAPTER 1 Noninvasive Diagnostic Techniques 5 Autopsy 8 Diagnosis of Disease 12 CHAPTER 2 Harmful and Beneficial Effects of Radiation 32 Free Radicals and Antioxidants 33 Artificial Sweeteners 46 Fatty Acids in Health and Disease 49 DNA Fingerprinting 56 CHAPTER 3 Medical Uses of Isotonic, Hypertonic, and Hypotonic Solutions 73 Digitalis Increases Ca2ϩ in Heart Muscle Cells 75 Viruses and Receptor-Mediated Endocytosis 76 Phagocytosis and Microbes 77 Cilia and Smoking 82 Smooth ER and Drug Tolerance 84 Tay-Sachs Disease 86 Proteasomes and Disease 87 Genomics 92 Recombinant DNA 94 Mitotic Spindle and Cancer 99 Tumor-Suppressor Genes 100 Free Radicals 104 Progeria and Werner Syndrome 104 Disorders: Homeostatic Imbalances 104 CHAPTER 4 Biopsy 114 Basement Membranes and Disease 118 Papanicolaou Test 119 Chondroitin Sulfate, Glucosamine, and Joint Disease 131 Marfan Syndrome 131 Liposuction 133 Tissue Engineering 138 Adhesions 146 Disorders: Homeostatic Imbalances 147 CHAPTER 5 Skin Grafts 156 Psoriasis 158 Stretch Marks 159 Tension Lines and Surgery 160 Albinism and Vitiligo 160 Skin Color as a Diagnostic Clue 161 Hair Removal 163 Chemotherapy and Hair Loss 163 Hair and Hormones 164 Acne 164 Impacted Cerumen 165 Transdermal Drug Administration 168 Sun Damage, Sunscreens, and Sunblocks 173 Disorders: Homeostatic Imbalances 175 CHAPTER 6 Bone Scan 188 Remodeling and Orthodontics 194 Paget’s Disease 194 Hormonal Abnormalities That Affect Height 196 Treatments for Fractures 198 Disorders: Homeostatic Imbalances 203 CHAPTER 7 Black Eye 214 Cleft Palate and Cleft Lip 225 Temporomandibular Joint Syndrome 226 Deviated Nasal Septum 227 Sinusitis 231 Caudal Anesthesia 244 Rib Fractures, Dislocations, and Separations 248 Disorders: Homeostatic Imbalances 249 CHAPTER 8 Fractured Clavicle 257 Boxer’s Fracture 266 Pelvimetry 271 Patellofemoral Stress Syndrome 276 Bone Grafting 278 Fractures of the Metatarsals 280 Flatfoot and Clawfoot 280 Disorders: Homeostatic Imbalances 285 CHAPTER 9 Autologous Chondrocyte Implantation 293 Aspiration of Synovial Fluid 294 Torn Cartilage and Arthroscopy 294 Sprain and Strain 295 Bursitis 295 Tenosynovitis 295 Dislocated Mandible 308 Rotator Cuff Injury, Dislocated and Separated Shoulder, and Torn Glenoid Labrum 312 Tennis Elbow, Little-League Elbow, and Dislocation of the Radial Head 313 Knee Injuries 319 Disorders: Homeostatic Imbalances 322 CHAPTER 10 Fibromyalgia 329 Muscular Hypertrophy, Fibrosis, and Muscular Atrophy 331 Exercise-Induced Muscle Damage 335 Rigor Mortis 341 Electromyography 345 Creatine Supplementation 345 Aerobic Training versus Strength Training 350 Hypotonia and Hypertonia 350 Anabolic Steroids 354 Disorders: Homeostatic Imbalances 359 CHAPTER 11 Intramuscular Injections 369 Benefits of Stretching 371 Bell’s Palsy 375 Strabismus 379 Gravity and the Mandible 381 Intubation during Anesthesia 384 Dysphagia 386 Inguinal Hernia 392 Injury of Levator Ani and Urinary Stress Incontinence 397 Rotator Cuff Injury and Impingement Syndrome 405 Golfer’s Elbow 411 Carpal Tunnel Syndrome 417 Back Injuries and Heavy Lifting 420 Groin Pull 423 xxxii JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxxii
  • Pulled Hamstrings and Charley Horse 429 Shin Splint Syndrome 433 Plantar Fasciitis 437 Disorders: Homeostatic Imbalances 442 CHAPTER 12 Neurotoxins and Local Anesthetics 470 Strychnine Poisoning 479 Excitotoxicity 480 Depression 482 Modifying the Effects of Neurotransmitters 483 Disorders: Homeostatic Imbalances 486 CHAPTER 13 Spinal Tap 493 Injuries to the Phrenic Nerves 504 Injuries to Nerves Emerging from the Brachial Plexus 505 Injuries to the Lumbar Plexus 509 Injury to the Sciatic Nerve 510 Reflexes and Diagnosis 519 Disorders: Homeostatic Imbalances 521 CHAPTER 14 Breaching the Blood–Brain Barrier 531 Hydrocephalus 533 Injury of the Medulla 538 Ataxia 543 Brain Injuries 551 Aphasia 554 Dental Anesthesia 557 Anosmia 558 Anopia 559 Strabismus, Ptosis, and Diplopia 561 Trigeminal Neuralgia 563 Bell’s Palsy 564 Vertigo, Ataxia, and Nystagmus 565 Dysphagia, Aptyalia, and Ageusia 566 Vagal Paralysis, Dysphagia, and Tachycardia 567 Paralysis of the Sternocleidomastoid and Trapezius Muscles 568 Dysarthria and Dysphagia 569 Disorders: Homeostatic Imbalances 573 CHAPTER 15 Horner’s Syndrome 591 Disorders: Homeostatic Imbalances 601 CHAPTER 16 Phantom Limb Sensation 611 Analgesia: Relief from Pain 613 Syphilis 620 Paralysis 621 Amyotrophic Lateral Sclerosis 624 Disorders of the Basal Nuclei 625 Sleep Disorders 628 Amnesia 629 Disorders: Homeostatic Imbalances 630 CHAPTER 17 Hyposmia 639 Taste Aversion 642 Detached Retina 647 Age-Related Macular Disease 649 Presbyopia 652 LASIK 652 Color Blindness and Night Blindness 655 Loud Sounds and Hair Cell Damage 661 Cochlear Implants 665 Motion Sickness 671 Disorders: Homeostatic Imbalances 674 CHAPTER 18 Blocking Hormone Receptors 683 Administering Hormones 684 Diabetogenic Effect of hGH 692 Oxytocin and Childbirth 695 Congenital Adrenal Hyperplasia 706 Seasonal Affective Disorder and Jet Lag 712 Nonsteroidal Anti-inflammatory Drugs 713 Posttraumatic Stress Disorder 714 Disorders: Homeostatic Imbalances 719 CHAPTER 19 Withdrawing Blood 729 Bone Marrow Examination 733 Medical Uses of Hemopoietic Growth Factors 734 Iron Overload and Tissue Damage 737 Reticulocyte Count 737 Blood Doping 738 Complete Blood Count 741 Anticoagulants 747 Aspirin and Thrombolytic Agents 747 Hemolytic Disease of the Newborn 750 Disorders: Homeostatic Imbalances 751 CHAPTER 20 Cardiopulmonary Resuscitation 758 Pericarditis 758 Myocarditis and Endocarditis 761 Heart Valve Disorders 768 Myocardial Ischemia and Infarction 771 Regeneration of Heart Cells 772 Artificial Pacemakers 775 Heart Murmurs 781 Congestive Heart Failure 783 Disorders: Homeostatic Imbalances 791 CHAPTER 21 Angiogenesis and Disease 803 Varicose Veins 810 Edema 814 Syncope 816 Carotid Sinus Massage and Carotid Sinus Syncope 820 Disorders: Homeostatic Imbalances 868 CHAPTER 22 Metastasis through Lymphatic Vessels 884 Ruptured Spleen 884 Tonsillitis 885 Microbial Evasion of Phagocytosis 888 Abscesses and Ulcers 890 Cytokine Therapy 896 Graft Rejection and Tissue Typing 900 Severe Combined Immunodeficiency Disease 901 Monoclonal Antibodies 903 Cancer Immunology 907 Disorders: Homeostatic Imbalances 910 CHAPTER 23 Rhinoplasty 919 Tonsillectomy 923 xxxiii JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxxiii
  • Laryngitis and Cancer of the Larynx 927 Tracheotomy and Intubation 928 Pneumothorax and Hemothorax 929 Coryza, Seasonal Influenza, and H1N1 Influenza 934 Respiratory Distress Syndrome 940 Hyperbaric Oxygenation 944 Carbon Monoxide Poisoning 950 Hypoxia 955 Effects of Smoking on the Respiratory System 956 Disorders: Homeostatic Imbalances 959 CHAPTER 24 Peritonitis 974 Mumps 977 Root Canal Therapy 978 Gastroesophageal Reflux Disease 982 Pylorospasm and Pyloric Stenosis 984 Vomiting 988 Pancreatitis and Pancreatic Cancer 990 Jaundice 993 Liver Function Tests 994 Gallstones 994 Lactose Intolerance 1000 Absorption of Alcohol 1005 Appendicitis 1006 Polyps in the Colon 1009 Occult Blood 1010 Dietary Fiber 1011 Disorders: Homeostatic Imbalances 1016 CHAPTER 25 Carbohydrate Loading 1036 Ketosis 1040 Phenylketonuria 1041 Hypothermia 1051 Emotional Eating 1052 Vitamin and Mineral Supplements 1054 Disorders: Homeostatic Imbalances 1058 CHAPTER 26 Nephroptosis (Floating Kidney) 1069 Kidney Transplant 1071 Loss of Plasma Proteins in Urine Causes Edema 1079 Glucosuria 1083 Diuretics 1092 Dialysis 1095 Cystoscopy 1097 Urinary Incontinence 1099 Disorders: Homeostatic Imbalances 1103 CHAPTER 27 Enemas and Fluid Balance 1115 Indicators of Naϩ Imbalance 1117 Diagnosis of Acid–Base Imbalances 1124 CHAPTER 28 Cryptorchidism 1135 Circumcision 1141 Premature Ejaculation 1143 Ovarian Cysts 1149 Uterine Prolapse 1152 Hysterectomy 1154 Breast Augmentation and Reduction 1158 Episiotomy 1158 Fibrocystic Disease of the Breasts 1159 Female Athlete Triad: Disordered Eating, Amenorrhea, and Premature Osteoporosis 1164 Disorders: Homeostatic Imbalances 1172 CHAPTER 29 Stem Cell Research and Therapeutic Cloning 1184 Ectopic Pregnancy 1186 Anencephaly 1192 Placenta Previa 1195 Early Pregnancy Tests 1203 Pregnancy-Induced Hypertension 1206 Dystocia and Cesarean Section 1208 Premature Infants 1209 Disorders: Homeostatic Imbalances 1216 xxxiv JWCL316_fm_i-xxxiv.qxd 17/11/2010 21:24 Page xxxiv
  • THE HUMAN BODY AND HOMEOSTASIS Humans have many ways to maintain homeostasis, the state of relative stability of the body’s internal environment. Disruptions to homeostasis often set in motion corrective cycles, called feedback systems, that help restore the condi- tions needed for health and life. 1 1 AN INTRODUCTION TO THE HUMAN BODY ? Did you ever wonder why an autopsy is performed? Our fascinating journey through the human body begins with an overview of the meanings of anatomy and physiology, followed by a discussion of the organization of the human body and the properties that it shares with all living things. Next, you will discover how the body regulates its own internal environment; this unceasing process, called homeostasis, is a major theme in every chapter of this book. Finally, we introduce the basic vocabulary that will help you speak about the body in a way that is understood by scientists and health-care professionals alike. JWCL316_c01_001-028.qxd 7/27/10 5:36 PM Page 1
  • 1.1 ANATOMY AND PHYSIOLOGY DEFINED O B J E C T I V E • Define anatomy and physiology, and name several subspecialties of these sciences. Two branches of science—anatomy and physiology—provide the foundation for understanding the body’s parts and functions. Anatomy (a-NAT-o¯-me¯; ana- ϭ up; -tomy ϭ process of cutting) is the science of body structures and the relationships among them. It was first studied by dissection (dis-SEK-shun; dis- ϭ apart; -section ϭ act of cutting), the careful cutting apart of body struc- tures to study their relationships. Today, a variety of imaging tech- niques (see Table 1.3) also contribute to the advancement of anatom- ical knowledge. Whereas anatomy deals with structures of the body, physiology (fizЈ-e¯-OL-o¯-je¯; physio- ϭ nature; -logy ϭ study of) is the science of body functions—how the body parts work. Table 1.1 describes several subspecialties of anatomy and physiology. Because structure and function are so closely related, you will learn about the human body by studying its anatomy and physiol- ogy together. The structure of a part of the body often reflects its functions. For example, the bones of the skull join tightly to form a rigid case that protects the brain. The bones of the fingers are more loosely joined to allow a variety of movements. The walls of the air sacs in the lungs are very thin, permitting rapid movement of inhaled oxygen into the blood. The lining of the urinary blad- der is much thicker to prevent the escape of urine into the pelvic cavity, yet its construction allows for considerable stretching. C H E C K P O I N T 1. What body function might a respiratory therapist strive to improve? What structures are involved? 2. Give your own example of how the structure of a part of the body is related to its function. 1.2 LEVELS OF STRUCTURAL ORGANIZATION AND BODY SYSTEMS O B J E C T I V E S • Describe the body’s six levels of structural organization. • List the 11 systems of the human body, representative organs present in each, and their general functions. The levels of organization of a language—letters, words, sen- tences, paragraphs, and so on—can be compared to the levels of 2 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY TABLE 1.1 Selected Subspecialties of Anatomy and Physiology SUBSPECIALTIES OF ANATOMY STUDY OF Embryology The first eight weeks of (em’-bre¯-OL-o¯-je¯; development after fertilization embry- ϭ embryo; -logy ϭ study of) of a human egg. Developmental biology The complete development of an individual from fertilization to death. Cell biology Cellular structure and functions. Histology Microscopic structure of tissues. (hiss’-TOL-o¯ -je¯; hist- ϭ tissue) Gross anatomy Structures that can be examined without a microscope. Systemic anatomy Structure of specific systems of the body such as the nervous or respiratory systems. Regional anatomy Specific regions of the body such as the head or chest. Surface anatomy Surface markings of the body to understand internal anatomy through visualization and palpation (gentle touch). Radiographic anatomy Body structures that can be (ra¯’-de¯-o¯-GRAF-ik; visualized with x-rays. radio- ϭ ray; -graphic ϭ to write) Pathological anatomy Structural changes (gross to (path’-o¯-LOJ-i-kal; microscopic) associated with path- ϭ disease) disease. SUBSPECIALTIES OF PHYSIOLOGY STUDY OF Neurophysiology Functional properties of nerve cells. (NOOR-o¯-fiz-e¯-ol’-o¯ -je¯; neuro- ϭ nerve) Endocrinology Hormones (chemical regulators in (en’-do¯-kri-NOL-o¯-je¯; the blood) and how they control endo- ϭ within; -crin ϭ secretion) body functions. Cardiovascular physiology Functions of the heart and blood (kar-de¯-o¯-VAS-ku¯-lar; vessels. cardi- ϭ heart; -vascular ϭ blood vessels) Immunology The body’s defenses against (im’-u¯-NOL-o¯-je¯; disease-causing agents. immun- ϭ not susceptible) Respiratory physiology Functions of the air passageways (RES-pir-a-to’-re¯; and lungs. respira- ϭ to breathe) Renal physiology Functions of the kidneys. (RE¯ -nal; ren- ϭ kidney) Exercise physiology Changes in cell and organ functions due to muscular activity. Pathophysiology Functional changes associated with (PATH-o¯ -fiz-e¯-ol’-o¯ -je¯) disease and aging. JWCL316_c01_001-028.qxd 7/1/10 5:35 AM Page 2
  • organization of the human body. Your exploration of the human body will extend from atoms and molecules to the whole person. From the smallest to the largest, six levels of organization will help you to understand anatomy and physiology: the chemical, cellular, tissue, organ, system, and organismal levels of organiza- tion (Figure 1.1). ●1 Chemical level. This very basic level can be compared to the letters of the alphabet and includes atoms, the smallest 1.2 LEVELS OF STRUCTURAL ORGANIZATION AND BODY SYSTEMS 3 units of matter that participate in chemical reactions, and molecules, two or more atoms joined together. Certain atoms, such as carbon (C), hydrogen (H), oxygen (O), nitro- gen (N), phosphorus (P), calcium (Ca), and sulfur (S), are es- sential for maintaining life. Two familiar molecules found in the body are deoxyribonucleic acid (DNA), the genetic mate- rial passed from one generation to the next, and glucose, commonly known as blood sugar. Chapters 2 and 25 focus on the chemical level of organization. Figure 1.1 Levels of structural organization in the human body. The levels of structural organization are chemical, cellular, tissue, organ, system, and organismal. Which level of structural organization is composed of two or more different types of tissues that work together to perform a specific function? 6 3 4 5 1 CHEMICAL LEVEL Atoms (C, H, O, N, P) 2 CELLULAR LEVEL Molecule (DNA) Smooth muscle cell Smooth muscle tissue ORGANISMAL LEVEL SYSTEM LEVEL Mouth Liver Gallbladder Large intestine Esophagus Small intestine Pancreas (behind stomach) Stomach Digestive system Stomach Epithelial tissue Epithelial and connective tissues ORGAN LEVEL TISSUE LEVEL Smooth muscle tissue layers Pharynx (throat) Salivary glands JWCL316_c01_001-028.qxd 7/1/10 5:35 AM Page 3
  • are the stomach, skin, bones, heart, liver, lungs, and brain. Fig- ure 1.1 shows how several tissues make up the stomach. The stomach’s outer covering is a layer of epithelial tissue and con- nective tissue that reduces friction when the stomach moves and rubs against other organs. Underneath are three layers of a type of muscular tissue called smooth muscle tissue, which contracts to churn and mix food and then push it into the next digestive organ, the small intestine. The innermost lining is an epithelial tissue layer that produces fluid and chemicals responsible for digestion in the stomach. ●5 System level. A system (or chapter in our language analogy) consists of related organs (paragraphs) with a common func- tion. An example of the system level, also called the organ- system level, is the digestive system, which breaks down and absorbs food. Its organs include the mouth, salivary glands, pharynx (throat), esophagus (food tube), stomach, small in- testine, large intestine, liver, gallbladder, and pancreas. Sometimes an organ is part of more than one system. The pancreas, for example, is part of both the digestive system and the hormone-producing endocrine system. ●6 Organismal level. An organism (OR-ga-nizm), any living in- dividual, can be compared to a book in our analogy.All the parts of the human body functioning together constitute the total organism. In the chapters that follow, you will study the anatomy and physiology of the body systems. Table 1.2 lists the components and introduces the functions of these systems. You will also dis- cover that all body systems influence one another. As you study 4 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY ●2 Cellular level. Molecules combine to form cells, the basic structural and functional units of an organism that are com- posed of chemicals. Just as words are the smallest elements of language that make sense, cells are the smallest living units in the human body. Among the many kinds of cells in your body are muscle cells, nerve cells, and epithelial cells. Figure 1.1 shows a smooth muscle cell, one of the three types of muscle cells in the body. The cellular level of organization is the focus of Chapter 3. ●3 Tissue level. Tissues are groups of cells and the materials sur- rounding them that work together to perform a particular func- tion, similar to the way words are put together to form sentences. There are just four basic types of tissues in your body: epithelial tissue, connective tissue, muscular tissue, and nervous tissue. Epithelial tissue covers body surfaces, lines hol- low organs and cavities, and forms glands. Connective tissue connects, supports, and protects body organs while distributing blood vessels to other tissues. Muscular tissue contracts to make body parts move and generates heat. Nervous tissue car- ries information from one part of the body to another through nerve impulses. Chapter 4 describes the tissue level of organiza- tion in greater detail. Shown in Figure 1.1 is smooth muscle tis- sue, which consists of tightly packed smooth muscle cells. ●4 Organ level. At the organ level different types of tissues are joined together. Similar to the relationship between sentences and paragraphs, organs are structures that are composed of two or more different types of tissues; they have specific func- tions and usually have recognizable shapes. Examples of organs TABLE 1.2 The Eleven Systems of the Human Body INTEGUMENTARY SYSTEM (CHAPTER 5) Components: Skin and associated structures, such as hair, fingernails and toenails, sweat glands, and oil glands. Functions: Protects body; helps regulate body temperature; eliminates some wastes; helps make vitamin D; detects sensations such as touch, pain, warmth, and cold. SKELETAL SYSTEM (CHAPTERS 6–9) Components: Bones and joints of the body and their associated cartilages. Functions: Supports and protects body; provides surface area for muscle attachments; aids body movements; houses cells that produce blood cells; stores minerals and lipids (fats). Hair Skin and associated glands Fingernails Toenails Bone Cartilage Joint JWCL316_c01_001-028.qxd 7/1/10 5:35 AM Page 4
  • C H E C K P O I N T 3. Define the following terms: atom, molecule, cell, tissue, organ, system, and organism. 4. At what levels of organization would an exercise physiologist study the human body? (Hint: Refer to Table 1.1.) 5. Referring to Table 1.2, which body systems help eliminate wastes? 1.3 CHARACTERISTICS OF THE LIVING HUMAN ORGANISM O B J E C T I V E S • Define the important life processes of the human body. • Define homeostasis and explain its relationship to interstitial fluid. Basic Life Processes Certain processes distinguish organisms, or living things, from nonliving things. Following are the six most important life processes of the human body: 1. Metabolism (me-TAB-o¯ -lizm) is the sum of all the chemical processes that occur in the body. One phase of metabolism is catabolism (ka-TAB-o¯ -lizm; catabol- ϭ throwing down; -ism ϭ a condition), the breakdown of complex chemical substances into simpler components. The other phase of 1.3 CHARACTERISTICS OF THE LIVING HUMAN ORGANISM 5 each of the body systems in more detail, you will discover how they work together to maintain health, provide protection from disease, and allow for reproduction of the human species. Health-care professionals and students of anatomy and physiology commonly use several noninvasive diagnostic techniques to assess cer- tain aspects of body structure and function. A noninvasive diagnostic technique is one that does not involve insertion of an instrument or device through the skin or a body opening. In inspection, the exam- iner observes the body for any changes that deviate from normal. For example, a physician may examine the mouth cavity for evidence of disease. Following inspection, one or more additional techniques may be employed. In palpation (pal-PA¯ -shun; palp- ϭ gently touching) the examiner feels body surfaces with the hands. An example is palpating the abdomen to detect enlarged or tender internal organs or abnor- mal masses. In auscultation (aws-kul-TA¯-shun; auscult- ϭ listening) the examiner listens to body sounds to evaluate the functioning of certain organs, often using a stethoscope to amplify the sounds. An example is auscultation of the lungs during breathing to check for crackling sounds associated with abnormal fluid accumulation. In percussion (pur-KUSH-un; percus- ϭ beat through) the examiner taps on the body surface with the fingertips and listens to the resulting echo. For example, percussion may reveal the abnormal presence of fluid in the lungs or air in the intestines. It may also provide informa- tion about the size, consistency, and position of an underlying struc- ture. An understanding of anatomy is important for the effective application of most of these diagnostic techniques. • CLINICAL CONNECTION | Noninvasive Diagnostic Techniques MUSCULAR SYSTEM (CHAPTERS 10, 11) Components: Specifically, skeletal muscle tissue—muscle usually attached to bones (other muscle tissues include smooth and cardiac). Functions: Participates in body movements, such as walking; maintains posture; produces heat. NERVOUS SYSTEM (CHAPTERS 12–17) Components: Brain, spinal cord, nerves, and special sense organs, such as eyes and ears. Functions: Generates action potentials (nerve impulses) to regulate body activities; detects changes in body’s internal and external environments, interprets changes, and responds by causing muscular contractions or glandular secretions. Skeletal muscle Tendon Nerve Spinal cord Brain TABLE 1.2 CONTINUES JWCL316_c01_001-028.qxd 7/1/10 5:35 AM Page 5
  • TABLE 1.2 CONTINUED The Eleven Systems of the Human Body ENDOCRINE SYSTEM (CHAPTER 18) Components: Hormone-producing glands (pineal gland, hypothalamus, pituitary gland, thymus, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries, and testes) and hormone-producing cells in several other organs. Functions: Regulates body activities by releasing hormones (chemical messengers transported in blood from endocrine gland or tissue to target organ). CARDIOVASCULAR SYSTEM (CHAPTERS 19–21) Components: Blood, heart, and blood vessels. Functions: Heart pumps blood through blood vessels; blood carries oxygen and nutrients to cells and carbon dioxide and wastes away from cells and helps regulate acid–base balance, temperature, and water content of body fluids; blood components help defend against disease and repair damaged blood vessels. LYMPHATIC SYSTEM AND IMMUNITY (CHAPTER 22) Components: Lymphatic fluid and vessels; spleen, thymus, lymph nodes, and tonsils; cells that carry out immune responses (B cells, T cells, and others). Functions: Returns proteins and fluid to blood; carries lipids from gastrointestinal tract to blood; contains sites of maturation and proliferation of B cells and T cells that protect against disease-causing microbes. RESPIRATORY SYSTEM (CHAPTER 23) Components: Lungs and air passageways such as the pharynx (throat), larynx (voice box), trachea (windpipe), and bronchial tubes leading into and out of lungs. Functions: Transfers oxygen from inhaled air to blood and carbon dioxide from blood to exhaled air; helps regulate acid–base balance of body fluids; air flowing out of lungs through vocal cords produces sounds. Ovary (female) Pancreas Thyroid gland Pineal gland Pituitary gland Hypothalamus Testis (male) Adrenal gland Thyroid gland Posterior view Parathyroid glands Lymphatic vessel Lymph node Red bone marrow Spleen Thymus Thoracic duct Pharyngeal tonsil Palatine tonsil Lingual tonsil Lung Bronchus Larynx (voice box) Pharynx (throat) Trachea (windpipe) Nasal cavity Oral cavity Larynx (voice box) Pharynx (throat) Blood vessels: Artery Vein Heart 6 JWCL316_c01_001-028.qxd 7/27/10 5:36 PM Page 6
  • metabolism is anabolism (a-NAB-o¯-lizm; anabol- ϭ a rais- ing up), the building up of complex chemical substances from smaller, simpler components. For example, digestive processes catabolize (split) proteins in food into amino acids. These amino acids are then used to anabolize (build) new pro- teins that make up body structures such as muscles and bones. 2. Responsiveness is the body’s ability to detect and respond to changes. For example, an increase in body temperature during a fever represents a change in the internal environment (within the body), and turning your head toward the sound of squealing brakes is a response to a change in the external environment (out- side the body) to prepare the body for a potential threat. Different DIGESTIVE SYSTEM (CHAPTER 24) Components: Organs of gastrointestinal tract, a long tube that includes the mouth, pharynx (throat), esophagus (food tube), stomach, small and large intestines, and anus; also includes accessory organs that assist in digestive processes, such as salivary glands, liver, gallbladder, and pancreas. Functions: Achieves physical and chemical breakdown of food; absorbs nutrients; eliminates solid wastes. Pancreas (behind stomach) StomachLiver Esophagus Salivary gland Mouth Anus Gallbladder Large intestine Pharynx Rectum Small intestine Prostate Ductus (vas) deferensSeminal vesicle Penis Testis Epididymis Kidney Ureter Urethra Urinary bladder 1.3 CHARACTERISTICS OF THE LIVING HUMAN ORGANISM 7 URINARY SYSTEM (CHAPTER 26) Components: Kidneys, ureters, urinary bladder, and urethra. Functions: Produces, stores, and eliminates urine; eliminates wastes and regulates volume and chemical composition of blood; helps maintain the acid–base balance of body fluids; maintains body’s mineral balance; helps regulate production of red blood cells. Mammary gland Ovary Uterine (fallopian) tube Uterus Vagina REPRODUCTIVE SYSTEMS (CHAPTER 28) Components: Gonads (testes in males and ovaries in females) and associated organs (uterine tubes, uterus, vagina, and mammary glands in females and epididymides, ductus deferens, seminal vesicles, prostate, and penis in males). Functions: Gonads produce gametes (sperm or oocytes) that unite to form a new organism; gonads also release hormones that regulate reproduction and other body processes; associated organs transport and store gametes; mammary glands produce milk. JWCL316_c01_001-028.qxd 10/11/10 11:55 AM Page 7
  • 8 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY C H E C K P O I N T 6. List the six most important life processes in the human body. 1.4 HOMEOSTASIS O B J E C T I V E S • Define homeostasis. • Describe the components of a feedback system. • Contrast the operation of negative and positive feedback systems. • Explain how homeostatic imbalances are related to disorders. Homeostasis (ho¯Ј-me¯-o¯-STA¯ -sis; homeo- ϭ sameness; -stasis ϭ standing still) is the condition of equilibrium (balance) in the body’s internal environment due to the constant interaction of the body’s many regulatory processes. Homeostasis is a dynamic condition. In response to changing conditions, the body’s equilib- rium can shift among points in a narrow range that is compatible with maintaining life. For example, the level of glucose in blood normally stays between 70 and 110 milligrams of glucose per 100 milliliters of blood.* Each structure, from the cellular level to the system level, contributes in some way to keeping the internal en- vironment of the body within normal limits. Homeostasis and Body Fluids An important aspect of homeostasis is maintaining the volume and composition of body fluids, dilute, watery solutions containing dissolved chemicals that are found inside cells as well as surround- ing them. The fluid within cells is intracellular fluid (intra- ϭ in- side), abbreviated ICF. The fluid outside body cells is extracellu- lar fluid (extra- ϭ outside), abbreviated ECF. The ECF that fills the narrow spaces between cells of tissues is known as interstitial fluid (inЈ-ter-STISH-al; inter- ϭ between). As you progress with your studies, you will learn that the ECF differs depending on where it occurs in the body: ECF within blood vessels is termed blood plasma, within lymphatic vessels it is called lymph, in and around the brain and spinal cord it is known as cerebrospinal fluid, in joints it is referred to as synovial fluid, and the ECF of the eyes is called aqueous humor and vitreous body. The proper functioning of body cells depends on precise regu- lation of the composition of the interstitial fluid surrounding them. Because of this, interstitial fluid is often called the body’s internal environment. The composition of interstitial fluid changes as sub- stances move back and forth between it and blood plasma. Such exchange of materials occurs across the thin walls of the smallest blood vessels in the body, the blood capillaries. This movement in both directions across capillary walls provides needed materials, cells in the body respond to environmental changes in character- istic ways. Nerve cells respond by generating electrical signals known as nerve impulses (action potentials). Muscle cells re- spond by contracting, which generates force to move body parts. 3. Movement includes motion of the whole body, individual or- gans, single cells, and even tiny structures inside cells. For ex- ample, the coordinated action of leg muscles moves your whole body from one place to another when you walk or run. After you eat a meal that contains fats, your gallbladder con- tracts and releases bile into the gastrointestinal tract to help di- gest them. When a body tissue is damaged or infected, certain white blood cells move from the bloodstream into the affected tissue to help clean up and repair the area. Inside the cell, var- ious parts, such as secretory vesicles (see Figure 3.20), move from one position to another to carry out their functions. 4. Growth is an increase in body size that results from an increase in the size of existing cells, an increase in the number of cells, or both. In addition, a tissue sometimes increases in size be- cause the amount of material between cells increases. In a growing bone, for example, mineral deposits accumulate be- tween bone cells, causing the bone to grow in length and width. 5. Differentiation (difЈ-er-en-she¯-A¯ -shun) is the development of a cell from an unspecialized to a specialized state. Such pre- cursor cells, which can divide and give rise to cells that un- dergo differentiation, are known as stem cells. As you will see later in the text, each type of cell in the body has a specialized structure and function that differs from that of its precursor (ancestor) cells. For example, red blood cells and several types of white blood cells all arise from the same unspecialized pre- cursor cells in red bone marrow. Also through differentiation, a single fertilized human egg (ovum) develops into an embryo, and then into a fetus, an infant, a child, and finally an adult. 6. Reproduction (re¯-pro¯-DUK-shun) refers either to (1) the for- mation of new cells for tissue growth, repair, or replacement, or (2) the production of a new individual. In humans, the for- mer process occurs continuously throughout life, which con- tinues from one generation to the next through the latter process, the fertilization of an ovum by a sperm cell. When any one of the life processes ceases to occur properly, the result is death of cells and tissues, which may lead to death of the organism. Clinically, loss of the heartbeat, absence of sponta- neous breathing, and loss of brain functions indicate death in the human body. An autopsy (AW-top-se¯ ϭ seeing with one’s own eyes) or necropsy is a postmortem (after death) examination of the body and dis- section of its internal organs to confirm or determine the cause of death. An autopsy can uncover the existence of diseases not detected during life, determine the extent of injuries, and explain how those injuries may have contributed to a person’s death. It also may provide more informa- tion about a disease, assist in the accumulation of statistical data, and ed- ucate health-care students. Moreover, an autopsy can reveal conditions CLINICAL CONNECTION | Autopsy *Appendix A describes metric measurements. that may affect offspring or siblings (such as congenital heart defects). Sometimes an autopsy is legally required, such as during a criminal inves- tigation. It may also be useful in resolving disputes between beneficiar- ies and insurance companies about the cause of death. • JWCL316_c01_001-028.qxd 7/1/10 5:35 AM Page 8
  • nerve impulses, or hormones or other chemical signals. This pathway is called an efferent pathway (EF-er-ent; ef- ϭ away from), since the information flows away from the control cen- ter. In our skin temperature example, the brain acts as the con- trol center, receiving nerve impulses from the skin receptors and generating nerve impulses as output. 3. An effector (e-FEK-tor) is a body structure that receives output from the control center and produces a response or effect that changes the controlled condition. Nearly every organ or tissue in the body can behave as an effector. When your body temperature drops sharply, your brain (control center) sends nerve impulses 1.4 HOMEOSTASIS 9 such as glucose, oxygen, ions, and so on, to tissue cells. It also re- moves wastes, such as carbon dioxide, from interstitial fluid. Control of Homeostasis Homeostasis in the human body is continually being disturbed. Some disruptions come from the external environment in the form of physical insults such as the intense heat of a hot summer day or a lack of enough oxygen for that two-mile run. Other disruptions orig- inate in the internal environment, such as a blood glucose level that falls too low when you skip breakfast. Homeostatic imbalances may also occur due to psychological stresses in our social environment— the demands of work and school, for example. In most cases the disruption of homeostasis is mild and temporary, and the responses of body cells quickly restore balance in the internal environment. However, in some cases the disruption of homeostasis may be in- tense and prolonged, as in poisoning, overexposure to temperature extremes, severe infection, or major surgery. Fortunately, the body has many regulating systems that can usually bring the internal environment back into balance. Most often, the nervous system and the endocrine system, working to- gether or independently, provide the needed corrective measures. The nervous system regulates homeostasis by sending electrical signals known as nerve impulses (action potentials) to organs that can counteract changes from the balanced state. The endocrine system includes many glands that secrete messenger molecules called hormones into the blood. Nerve impulses typically cause rapid changes, but hormones usually work more slowly. Both means of regulation, however, work toward the same end, usually through negative feedback systems. Feedback Systems The body can regulate its internal environment through many feedback systems. A feedback system or feedback loop is a cycle of events in which the status of a body condition is monitored, evaluated, changed, remonitored, reevaluated, and so on. Each monitored variable, such as body temperature, blood pressure, or blood glucose level, is termed a controlled condition. Any disrup- tion that changes a controlled condition is called a stimulus. A feedback system includes three basic components: a receptor, a control center, and an effector (Figure 1.2). 1. A receptor is a body structure that monitors changes in a con- trolled condition and sends input to a control center. This path- way is called an afferent pathway (AF-er-ent; af- ϭ toward; -ferrent ϭ carried), since the information flows toward the control center. Typically, the input is in the form of nerve im- pulses or chemical signals. For example, certain nerve endings in the skin sense temperature and can detect changes, such as a dramatic drop in temperature. 2. A control center in the body, for example, the brain, sets the range of values within which a controlled condition should be maintained (set point), evaluates the input it receives from re- ceptors, and generates output commands when they are needed. Output from the control center typically occurs as Effectors that bring about a change or Control center Controlled condition that is monitored by Receptors that send Some stimulus disrupts homeostasis by Nerve impulses or chemical signals to a Increasing or decreasing a Nerve impulses or chemical signals to There is a return to homeostasis when the response brings the controlled condition back to normal. that receives the input and provides Response that alters the controlled condition. Input Output Figure 1.2 Operation of a feedback system. The dashed return arrow symbolizes negative feedback. The three basic components of a feedback system are the receptor, control center, and effector. What is the main difference between negative and positive feedback systems? JWCL316_c01_001-028.qxd 7/1/10 5:35 AM Page 9
  • 10 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY Figure 1.3 Homeostatic regulation of blood pressure by a negative feedback system. Note that the response is fed back into the system, and the system continues to lower blood pressure until there is a return to normal blood pressure (homeostasis). If the response reverses the stimulus, a system is operating by negative feedback. What would happen to heart rate if some stimulus caused blood pressure to decrease? Would this occur by way of positive or negative feedback? A decrease in heart rate decreases blood pressure Effector Control center Receptors Blood pressure Baroreceptors in certain blood vessels send Some stimulus disrupts homeostasis by Input Output Nerve impulses Nerve impulses Heart Return to homeostasis when response brings blood pressure back to normal Increasing Brain interprets input and sends Blood vessels (output) to your skeletal muscles (effectors). The result is shiver- ing, which generates heat and raises your body temperature. A group of receptors and effectors communicating with their control center forms a feedback system that can regulate a con- trolled condition in the body’s internal environment. In a feed- back system, the response of the system “feeds back” information to change the controlled condition in some way, either negating it (negative feedback) or enhancing it (positive feedback). NEGATIVE FEEDBACK SYSTEMS A negative feedback system reverses a change in a controlled condition. Consider the regula- tion of blood pressure. Blood pressure (BP) is the force exerted by blood as it presses against the walls of blood vessels. When the heart beats faster or harder, BP increases. If some internal or exter- nal stimulus causes blood pressure (controlled condition) to rise, the following sequence of events occurs (Figure 1.3). Barorecep- tors (the receptors), pressure-sensitive nerve cells located in the walls of certain blood vessels, detect the higher pressure. The baroreceptors send nerve impulses (input) to the brain (control center), which interprets the impulses and responds by sending nerve impulses (output) to the heart and blood vessels (the effec- tors). Heart rate decreases and blood vessels dilate (widen), which cause BP to decrease (response). This sequence of events quickly re- turns the controlled condition—blood pressure—to normal, and homeostasis is restored. Notice that the activity of the effector causes BP to drop, a result that negates the original stimulus (an in- crease in BP). This is why it is called a negative feedback system. POSITIVE FEEDBACK SYSTEMS Unlike a negative feedback sys- tem, a positive feedback system tends to strengthen or reinforce a change in one of the body’s controlled conditions. In a positive feedback system, the response affects the controlled condition dif- ferently than in a negative feedback system. The control center still provides commands to an effector, but this time the effector pro- duces a physiological response that adds to or reinforces the initial change in the controlled condition. The action of a positive feed- back system continues until it is interrupted by some mechanism. Normal childbirth provides a good example of a positive feed- back system (Figure 1.4). The first contractions of labor (stimu- lus) push part of the fetus into the cervix, the lowest part of the uterus, which opens into the vagina. Stretch-sensitive nerve cells (receptors) monitor the amount of stretching of the cervix (con- trolled condition). As stretching increases, they send more nerve impulses (input) to the brain (control center), which in turn re- leases the hormone oxytocin (output) into the blood. Oxytocin causes muscles in the wall of the uterus (effector) to contract even more forcefully. The contractions push the fetus farther down the uterus, which stretches the cervix even more. The cycle of stretch- ing, hormone release, and ever-stronger contractions is inter- rupted only by the birth of the baby. Then, stretching of the cervix ceases and oxytocin is no longer released. Another example of positive feedback is what happens to your body when you lose a great deal of blood. Under normal condi- tions, the heart pumps blood under sufficient pressure to body cells to provide them with oxygen and nutrients to maintain homeosta- sis. Upon severe blood loss, blood pressure drops and blood cells JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 10
  • 1.4 HOMEOSTASIS 11 (including heart cells) receive less oxygen and function less effi- ciently. If the blood loss continues, heart cells become weaker, the pumping action of the heart decreases further, and blood pressure continues to fall. This is an example of a positive feedback cycle that has serious consequences and may even lead to death if there is no medical intervention. As you will see in Chapter 19, blood clotting is also an example of a positive feedback system. These examples suggest some important differences between positive and negative feedback systems. Because a positive feed- back system continually reinforces a change in a controlled con- dition, some event outside the system must shut it off. If the action of a positive feedback system is not stopped, it can “run away” and may even produce life-threatening conditions in the body. The action of a negative feedback system, by contrast, slows and then stops as the controlled condition returns to its normal state. Usually, positive feedback systems reinforce conditions that do not happen very often, and negative feedback systems regulate conditions in the body that remain fairly stable over long periods. Homeostatic Imbalances You’ve seen homeostasis defined as a condition in which the body’s internal environment remains relatively stable. The body’s ability to maintain homeostasis gives it tremendous healing power and a remarkable resistance to abuse. The physiological processes responsible for maintaining homeostasis are in large part also responsible for your good health. For most people, lifelong good health is not something that happens effortlessly. The many factors in this balance called health include the following: • The environment and your own behavior. • Your genetic makeup. • The air you breathe, the food you eat, and even the thoughts you think. The way you live your life can either support or interfere with your body’s ability to maintain homeostasis and recover from the inevitable stresses life throws your way. Many diseases are the result of years of poor health behavior that interferes with the body’s natural drive to maintain homeostasis.An obvious example is smoking-related illness. Smoking tobacco ex- poses sensitive lung tissue to a multitude of chemicals that cause cancer and damage the lung’s ability to repair itself. Because dis- eases such as emphysema and lung cancer are difficult to treat and are very rarely cured, it is much wiser to quit smoking—or never start—than to hope a doctor can “fix” you once you are diagnosed with a lung disease. Developing a lifestyle that works with, rather than against, your body’s homeostatic processes helps you maxi- mize your personal potential for optimal health and well-being. As long as all of the body’s controlled conditions remain within certain narrow limits, body cells function efficiently, homeostasis is maintained, and the body stays healthy. Should one or more com- ponents of the body lose their ability to contribute to homeostasis, however, the normal balance among all of the body’s processes may be disturbed. If the homeostatic imbalance is moderate, a dis- order or disease may occur; if it is severe, death may result. Figure 1.4 Positive feedback control of labor contractions during birth of a baby. The solid return arrow symbolizes positive feedback. If the response enhances or intensifies the stimulus, a system is operating by positive feedback. Why do positive feedback systems that are part of a normal physiological response include some mechanism that terminates the system? Baby's body stretches cervix more Muscles in wall of uterus contract more forcefully Interruption of cycle: Birth of baby decreases stretching of cervix, thus breaking the positive feedback cycle Effectors Stretching of cervix Receptors Stretch-sensitive nerve cells in cervix send Positive feedback: Increased stretching of cervix causes release of more oxytocin, which results in more stretching of the cervix Contractions of wall of uterus force baby's head or body into the cervix, thus Input Output Nerve impulses Increasing Brain interprets input and releases Oxytocin Control center JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 11
  • C H E C K P O I N T 7. Describe the locations of intracellular fluid, extracellular fluid, interstitial fluid, and blood plasma. 8. Why is interstitial fluid called the internal environment of the body? 9. What types of disturbances can act as stimuli that initiate a feedback system? 10. Define receptor, control center, and effector. 11. What is the difference between symptoms and signs of a disease? Give examples of each. 1.5 BASIC ANATOMICAL TERMINOLOGY O B J E C T I V E S • Describe the anatomical position. • Relate the anatomical names and the corresponding common names for various regions of the human body. • Define the anatomical planes, anatomical sections, and directional terms used to describe the human body. • Outline the major body cavities, the organs they contain, and their associated linings. Scientists and health-care professionals use a common lan- guage of special terms when referring to body structures and their functions. The language of anatomy they use has precisely defined meanings that allow us to communicate clearly and pre- cisely. For example, is it correct to say, “The wrist is above the fingers”? This might be true if your upper limbs (described shortly) are at your sides. But if you hold your hands up above your head, your fingers would be above your wrists. To prevent this kind of confusion, anatomists use a standard anatomical position and a special vocabulary for relating body parts to one another. Body Positions Descriptions of any region or part of the human body assume that it is in a standard position of reference called the anatomical po- sition (anЈ-a-TOM-i-kal). In the anatomical position, the subject stands erect facing the observer, with the head level and the eyes facing directly forward. The feet are flat on the floor and directed forward, and the upper limbs are at the sides with the palms turned forward (Figure 1.5). In the anatomical position, the body is upright. Two terms describe a reclining body. If the body is ly- ing face down, it is in the prone position. If the body is lying face up, it is in the supine position. Regional Names The human body is divided into several major regions that can be identified externally. The principal regions are the head, neck, trunk, upper limbs, and lower limbs (Figure 1.5). The head consists of the skull and face. The skull encloses and pro- tects the brain; the face is the front portion of the head that in- cludes the eyes, nose, mouth, forehead, cheeks, and chin. The neck supports the head and attaches it to the trunk. The trunk consists of the chest, abdomen, and pelvis. Each upper limb at- taches to the trunk and consists of the shoulder, armpit, arm (portion of the limb from the shoulder to the elbow), forearm (portion of the limb from the elbow to the wrist), wrist, and hand. Each lower limb also attaches to the trunk and consists of the buttock, thigh (portion of the limb from the buttock to the knee), leg (portion of the limb from the knee to the ankle), an- kle, and foot. The groin is the area on the front surface of the body marked by a crease on each side, where the trunk attaches to the thighs. Figure 1.5 shows the anatomical and common names of ma- jor parts of the body. The anatomical term in the form of an ad- jective for each part appears first and is followed in parentheses by the corresponding common name. For example, if you re- ceive a tetanus shot in your gluteal region, it is an injection in your buttock. Because the anatomical term for a body part usu- ally is based on a Greek or Latin word, it may look different 12 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY Diagnosis (di’-ag-NO¯ -sis; dia- ϭ through; -gnosis ϭ knowledge) is the science and skill of distinguishing one disorder or disease from another. The patient’s symptoms and signs, his or her medical history, a physical exam, and laboratory tests provide the basis for making a di- agnosis. Taking a medical history consists of collecting information about events that might be related to a patient’s illness. These include the chief complaint (primary reason for seeking medical attention), history of present illness, past medical problems, family medical prob- lems, social history, and review of symptoms. A physical examination is an orderly evaluation of the body and its functions. This process in- cludes the noninvasive techniques of inspection, palpation, ausculta- tion, and percussion that you learned about earlier in the chapter, along with measurement of vital signs (temperature, pulse, respira- tory rate, and blood pressure), and sometimes laboratory tests. • CLINICAL CONNECTION | Diagnosis of Disease A disorder is any abnormality of structure or function. Dis- ease is a more specific term for an illness characterized by a rec- ognizable set of signs and symptoms. A local disease affects one part or a limited region of the body (for example, a sinus infec- tion); a systemic disease affects either the entire body or several parts of it (for example, influenza). Diseases alter body structures and functions in characteristic ways. A person with a disease may experience symptoms, subjective changes in body functions that are not apparent to an observer. Examples of symptoms are headache, nausea, and anxiety. Objective changes that a clinician can observe and measure are called signs. Signs of disease can be either anatomical, such as swelling or a rash, or physiological, such as fever, high blood pressure, or paralysis. The science that deals with why, when, and where diseases oc- cur and how they are transmitted among individuals in a commu- nity is known as epidemiology (epЈ-i-de¯-me¯-OL-o¯-je¯; epi- ϭ upon; -demi ϭ people). Pharmacology (farЈ-ma-KOL-o¯-je¯; pharmac- ϭ drug) is the science that deals with the effects and uses of drugs in the treatment of disease. JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 12
  • from the common name for the same part or area. For example, the Latin word for axilla (ak-SIL-a) is the common name armpit. Thus, the axillary nerve is one of the nerves passing within the armpit. You will learn more about the Greek and Latin word roots of anatomical and physiological terms as you read this book. 1.5 BASIC ANATOMICAL TERMINOLOGY 13 Directional Terms To locate various body structures, anatomists use specific directional terms, words that describe the position of one body part relative to another. Several directional terms are grouped in pairs that have op- posite meanings, such as anterior (front) and posterior (back). Ex- hibit 1.A and Figure 1.6 present the main directional terms. (a) Anterior view (b) Posterior view Thoracic (chest) TRUNK Pelvic (pelvis) Abdominal (abdomen) CERVICAL (NECK) Brachial (arm) Axillary (armpit) Antecubital (Front of elbow) Carpal (wrist) Antebrachial (forearm) Patellar (anterior surface of knee) Pedal (foot) Digital or phalangeal (toes) Tarsal (ankle) Crural (leg) Femoral (thigh) Palmar or volar (palm) Pubic (pubis) Dorsum (top of foot) Hallux (great toe) Umbilical (navel) Coxal (hip) Inguinal (groin) Pollex (thumb) Mammary (breast) Sternal (breastbone) Mental (chin) Oral (mouth) Nasal (nose) Buccal (cheek) Otic (ear) Orbital or ocular (eye) Frontal (forehead) Temporal (temple) Manual (hand) Cranial (skull) Facial (face) CEPHALIC (HEAD) CEPHALIC (HEAD) CERVICAL (NECK) Digital or phalangeal (fingers) Olecranal or cubital (back of elbow) Sacral (between hips) Popliteal (hollow behind knee) Gluteal (buttock) Coccygeal (tailbone) Perineal (region between anus and external genitals) Plantar (sole) Sural (calf) Occipital (base of skull) Vertebral (spinal column) Scapular (shoulder blade) Acromial (shoulder) Dorsum (back of hand) UPPER LIMB Lumbar (loin) Calcaneal (heel) LOWER LIMB Figure 1.5 The anatomical position. The anatomical names and corresponding common names (in parentheses) are indicated for specific body regions. For example, the cephalic region is the head. In the anatomical position, the subject stands erect facing the observer with the head level and the eyes facing forward. The feet are flat on the floor and directed forward, and the upper limbs are at the sides with the palms facing forward. What is the usefulness of defining one standard anatomical position? JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 13
  • 14 EXHIBIT 1.A O B J E C T I V E • Define each directional term used to describe the human body. OVERVIEW Most of the directional terms used to describe the relationship of one part of the body to another can be grouped into pairs that have opposite meanings. For example, superior means toward the upper part of the body, and inferior means toward the lower part of the body. It is impor- tant to understand that directional terms have relative meanings; they EXHIBIT 1.A Directional Terms (Figure 1.6) make sense only when used to describe the position of one structure rel- ative to another. For example, your knee is superior to your ankle, even though both are located in the inferior half of the body. Study the direc- tional terms below and the example of how each is used. As you read the examples, look at Figure 1.6 to see the location of each structure. C H E C K P O I N T Which directional terms can be used to specify the relationships between (1) the elbow and the shoulder, (2) the left and right shoulders, (3) the sternum and the humerus, and (4) the heart and the diaphragm? DIRECTIONAL TERM Superior (soo’-PE¯ R-e¯-or) (cephalic or cranial) Inferior (in’-FE¯ R-e¯-or) (caudal) Anterior (an-TE¯R-e¯-or) (ventral)* Posterior (pos-TE¯R-e¯-or) (dorsal) Medial (ME¯-de¯-al) Lateral (LAT-er-al) Intermediate (in’-ter-ME¯ -de¯-at) Ipsilateral (ip-si-LAT-er-al) Contralateral (CON-tra-lat-er-al) Proximal (PROK-si-mal) Distal (DIS-tal) Superficial (soo’-per-FISH-al) (external) Deep (internal) DEFINITION Toward the head, or the upper part of a structure. Away from the head, or the lower part of a structure. Nearer to or at the front of the body. Nearer to or at the back of the body. Nearer to the midline.† Farther from the midline. Between two structures. On the same side of the body as another structure. On the opposite side of the body from another structure. Nearer to the attachment of a limb to the trunk; nearer to the origination of a structure. Farther from the attachment of a limb to the trunk; farther from the origination of a structure. Toward or on the surface of the body. Away from the surface of the body. EXAMPLE OF USE The heart is superior to the liver. The stomach is inferior to the lungs. The sternum (breastbone) is anterior to the heart. The esophagus (food tube) is posterior to the trachea (windpipe). The ulna is medial to the radius. The lungs are lateral to the heart. The transverse colon is intermediate between the ascending and descending colons. The gallbladder and ascending colon are ipsilateral. The ascending and descending colons are contralateral. The humerus (arm bone) is proximal to the radius. The phalanges (finger bones) are distal to the carpals (wrist bones). The ribs are superficial to the lungs. The ribs are deep to the skin of the chest and back. *Note that the terms anterior and ventral mean the same thing in humans. However, in four-legged animals ventral refers to the belly side and is therefore inferior. Similarly, the terms posterior and dorsal mean the same thing in humans, but in four-legged animals dorsal refers to the back side and is therefore superior. † Recall that the midline is an imaginary vertical line that divides the body into equal right and left sides. JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 14
  • EXHIBIT 1.A 15 Figure 1.6 Directional terms. Directional terms precisely locate various parts of the body relative to one another. Is the radius proximal to the humerus? Is the esophagus anterior to the trachea? Are the ribs superficial to the lungs? Is the urinary bladder medial to the ascending colon? Is the sternum lateral to the descending colon? Right lung Midline PROXIMAL Esophagus (food tube) Trachea (windpipe) Rib Left lung Heart Diaphragm Stomach Spleen Transverse colon Small intestine Descending colon Urinary bladder Anterior view of trunk and right upper limb INFERIOR SUPERIOR LATERAL MEDIAL LATERAL Sternum (breastbone) Humerus Liver Gallbladder Radius Ulna Ascending colon Carpals Metacarpals Phalanges DISTAL JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 15
  • Planes and Sections You will also study parts of the body relative to planes, imaginary flat surfaces that pass through the body parts (Figure 1.7). A sagit- tal plane (SAJ-i-tal; sagitt- ϭ arrow) is a vertical plane that di- vides the body or an organ into right and left sides. More specifi- cally, when such a plane passes through the midline of the body or an organ and divides it into equal right and left sides, it is called a midsagittal plane or a median plane. The midline is an imagi- nary vertical line that divides the body into equal left and right sides. If the sagittal plane does not pass through the midline but in- stead divides the body or an organ into unequal right and left sides, it is called a parasagittal plane (para- ϭ near).A frontal or coro- nal plane (ko¯-RO¯ -nal; corona ϭ crown) divides the body or an or- gan into anterior (front) and posterior (back) portions. A trans- verse plane divides the body or an organ into superior (upper) and inferior (lower) portions. Other names for a transverse plane are a cross-sectional or horizontal plane. Sagittal, frontal, and trans- verse planes are all at right angles to one another. An oblique plane (o¯-BLE¯K), by contrast, passes through the body or an organ at an oblique angle (any angle other than a 90-degree angle). 16 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY Figure 1.7 Planes through the human body. Frontal, transverse, sagittal, and oblique planes divide the body in specific ways. Which plane divides the heart into anterior and posterior portions? Figure 1.8 Planes and sections through different parts of the brain. The diagrams (left) show the planes, and the photographs (right) show the resulting sections. Note: The arrows in the diagrams indicate the direction from which each section is viewed. This aid is used throughout the book to indicate viewing perspectives. Planes divide the body in various ways to produce sections. Which plane divides the brain into unequal right and left portions? Parasagittal plane Transverse plane Frontal plane Midsagittal plane (through midline) Oblique plane Anterior view (a) (b) (c) Frontal plane Midsagittal plane Transverse plane View View View AnteriorPosterior Transverse section Frontal section Midsagittal section JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 16
  • When you study a body region, you often view it in section. A section is a cut of the body or one of its organs made along one of the planes just described. It is important to know the plane of the section so you can understand the anatomical relationship of one part to another. Figure 1.8a–c indicates how three different sections—transverse, frontal, and midsagittal—provide different views of the brain. Body Cavities Body cavities are spaces within the body that help protect, sepa- rate, and support internal organs. Bones, muscles, ligaments, and other structures separate the various body cavities from one an- other. Here we discuss several body cavities (Figure 1.9). The cranial bones form a hollow space of the head called the cranial cavity (KRA¯ -ne¯-al), which contains the brain. The bones of the vertebral column (backbone) form the vertebral (spinal) canal (VER-te-bral), which contains the spinal cord. The cranial cavity and vertebral canal are continuous with one another. Three layers of protective tissue, the meninges (me-NIN-je¯z), and a shock-absorbing fluid surround the brain and spinal cord. The major body cavities of the trunk are the thoracic and ab- dominopelvic cavities. The thoracic cavity (thor-AS-ik; thorac- ϭ chest) or chest cavity (Figure 1.10) is formed by the ribs, the muscles of the chest, the sternum (breastbone), and the thoracic portion of the vertebral column. Within the thoracic cavity are the pericardial cavity (perЈ-i-KAR-de¯-al; peri- ϭ around; -cardial ϭ heart), a fluid-filled space that surrounds the heart, and two fluid-filled spaces called pleural cavities (PLOOR-al; pleur- ϭ rib or side), one around each lung. The central part of the thoracic cavity is an anatomical region called the mediastinum (me¯Ј-de¯- as-TI¯-num; media- ϭ middle; -stinum ϭ partition). It is between the lungs, extending from the sternum to the vertebral column and from the first rib to the diaphragm (Figure 1.10a, b). The mediastinum 1.5 BASIC ANATOMICAL TERMINOLOGY 17 Figure 1.9 Body cavities. The dashed line in (a) indicates the border between the abdominal and pelvic cavities. The major cavities of the trunk are the thoracic and abdominopelvic cavities. In which cavities are the following organs located: urinary bladder, stomach, heart, small intestine, lungs, internal female reproductive organs, thymus, spleen, liver? Use the following symbols for your responses: T ‫؍‬ thoracic cavity, A ‫؍‬ abdominal cavity, or P ‫؍‬ pelvic cavity. Formed by cranial bones and contains brain. Formed by vertebral column and contains spinal cord and the beginnings of spinal nerves. Chest cavity; contains pleural and pericardial cavities and mediastinum. Each surrounds a lung; the serous membrane of each pleural cavity is the pleura. Surrounds the heart; the serous membrane of the pericardial cavity is the pericardium. Central portion of thoracic cavity between the lungs; extends from sternum to vertebral column and from first rib to diaphragm; contains heart, thymus, esophagus, trachea, and several large blood vessels. Subdivided into abdominal and pelvic cavities. Contains stomach, spleen, liver, gallbladder, small intestine, and most of large intestine; the serous membrane of the abdominal cavity is the peritoneum. Cranial cavity Vertebral canal Thoracic cavity* Pleural cavity Pericardial cavity Mediastinum Abdominopelvic cavity Abdominal cavity Pelvic cavity * See Figure 1.10 for details of the thoracic cavity. CAVITY COMMENTS (a) Right lateral view (b) Anterior view Cranial cavity Vertebral canal Thoracic cavity Abdominopelvic cavity: Abdominal cavity Diaphragm Pelvic cavity Contains urinary bladder, portions of large intestine, and internal organs of reproduction. JWCL316_c01_001-028.qxd 7/1/10 5:56 PM Page 17
  • contains all thoracic organs except the lungs themselves. Among the structures in the mediastinum are the heart, esophagus, tra- chea, thymus, and several large blood vessels that enter and exit the heart. The diaphragm (DI¯-a-fram ϭ partition or wall) is a dome-shaped muscle that separates the thoracic cavity from the abdominopelvic cavity. The abdominopelvic cavity (ab-domЈ-i-no¯-PEL-vik; see Fig- ure 1.9) extends from the diaphragm to the groin and is encircled 18 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY Figure 1.10 The thoracic cavity. The dashed lines indicate the borders of the mediastinum. Note: When transverse sections are viewed inferiorly (from below), the anterior aspect of the body appears on top and the left side of the body appears on the right side of the illustration. The thoracic cavity contains three smaller cavities and the mediastinum. What is the name of the cavity that surrounds the heart? Which cavities surround the lungs? Right pleural cavity Mediastinum Left pleural cavity (a) Anterior view of thoracic cavity Pericardial cavity Parietal pericardium Visceral pericardium Parietal pleura Visceral pleura Diaphragm Transverse plane View LEFT PLEURAL CAVITY Vertebral column (backbone) Esophagus (food tube) Left lung Sternum (breastbone) Thymus ANTERIOR (b) Inferior view of transverse section of thoracic cavity POSTERIOR Heart PERICARDIAL CAVITY RIGHT PLEURAL CAVITY Aorta Right lung Rib Muscle View JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 18
  • by the abdominal muscular wall and the bones and muscles of the pelvis. As the name suggests, the abdominopelvic cavity is di- vided into two portions, even though no wall separates them (Fig- ure 1.11). The superior portion, the abdominal cavity (ab-DOM- i-nal; abdomin- ϭ belly), contains the stomach, spleen, liver, gallbladder, small intestine, and most of the large intestine. The inferior portion, the pelvic cavity (PEL-vik; pelv- ϭ basin), con- tains the urinary bladder, portions of the large intestine, and inter- nal organs of the reproductive system. Organs inside the thoracic and abdominopelvic cavities are called viscera (VIS-er-a). Thoracic and Abdominal Cavity Membranes A membrane is a thin, pliable tissue that covers, lines, partitions, or connects structures. One example is a slippery, double-layered mem- brane called a serous membrane (SE¯R-us), which covers the viscera within the thoracic and abdominal cavities and also lines the walls of the thorax and abdomen. The parts of a serous membrane are (1) the parietal layer (pa-RI¯-e-tal), a thin epithelium that lines the walls of the cavities, and (2) the visceral layer (VIS-er-al), a thin epithelium that covers and adheres to the viscera within the cavities. A small amount of lubricating fluid (serous fluid) between the two layers re- duces friction, allowing the viscera to slide somewhat during move- ments, such as when the lungs inflate and deflate during breathing. The serous membrane of the pleural cavities is called the pleura (PLOO-ra). The visceral pleura clings to the surface of the lungs, and the anterior part of the parietal pleura lines the chest wall, cov- ering the superior surface of the diaphragm (see Figure 1.10a). In between is the pleural cavity, filled with a small amount of lubricat- ing fluid (see Figure 1.10). The serous membrane of the pericardial cavity is the pericardium (perЈ-i-KAR-de¯-um). The visceral peri- cardium covers the surface of the heart; the parietal pericardium lines the chest wall. Between them is the pericardial cavity, filled with a small amount of lubricating fluid (see Figure 1.10). The peri- toneum (per-i-to¯-NE¯-um) is the serous membrane of the abdominal cavity. The visceral peritoneum covers the abdominal viscera, and the parietal peritoneum lines the abdominal wall, covering the infe- rior surface of the diaphragm. Between them is the peritoneal cav- ity, which contains a small amount of lubricating fluid. Most ab- dominal organs are located in the peritoneal cavity. Some are located between the parietal peritoneum and the posterior abdomi- nal wall. Such organs are said to be retroperitoneal (reЈ-tro¯-per-i- to¯-NE¯-al; retro- ϭ behind). The kidneys, adrenal glands, pancreas, duodenum of the small intestine, ascending and descending colons of the large intestine, and portions of the abdominal aorta and infe- rior vena cava are retroperitoneal. In addition to the major body cavities just described, you will also learn about other body cavities in later chapters. These include the oral (mouth) cavity, which contains the tongue and teeth (see Figure 24.5); the nasal cavity in the nose (see Figure 23.1); the or- bital cavities (orbits), which contain the eyeballs (see Figure 7.3); the middle ear cavities (middle ears), which contain small bones (see Figure 17.4); and the synovial cavities, which are found in freely movable joints and contain synovial fluid (see Figure 9.3). A summary of the major body cavities and their membranes is presented in the table included in Figure 1.9. Abdominopelvic Regions and Quadrants To describe the location of the many abdominal and pelvic organs more easily, anatomists and clinicians use two methods of divid- ing the abdominopelvic cavity into smaller areas. In the first method, two horizontal and two vertical lines, aligned like a tic- tac-toe grid, partition this cavity into nine abdominopelvic re- gions (Figure 1.12a,b). The top horizontal line, the subcostal line (sub- ϭ under; costal ϭ rib), is drawn just inferior to the rib cage, across the inferior portion of the stomach; the bottom horizontal line, the transtubercular line (trans-too-BER-ku¯-lar), is drawn just inferior to the tops of the hip bones. Two vertical lines, the left and right midclavicular lines (mid-kla-VIK-u¯-lar), are drawn through the midpoints of the clavicles (collar bones), just medial to the nipples. The four lines divide the abdominopelvic cavity into a larger middle section and smaller left and right sections. 1.5 BASIC ANATOMICAL TERMINOLOGY 19 Figure 1.11 The abdominopelvic cavity. The dashed lower line shows the approximate boundary between the abdominal and pelvic cavities. The abdominopelvic cavity extends from the diaphragm to the groin. To which body systems do the organs shown here within the abdominal and pelvic cavities belong? (Hint: Refer to Table 1.2.) Liver Gallbladder Large intestine Abdominal cavity Abdominal cavity Pelvic cavityPelvic cavity Anterior view Diaphragm Stomach Small intestine Urinary bladder JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 19
  • 20 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY Figure 1.12 Regions and quadrants of the abdominopelvic cavity. The nine-region designation is used for anatomical studies; the quadrant designation is used to locate the site of pain, tumors, or some other abnormality. In which abdominopelvic region is each of the following found: most of the liver, ascending colon, urinary bladder, and most of the small intestine? In which abdominopelvic quadrant would pain from appendicitis (inflammation of the appendix) be felt? RIGHT HYPOCHONDRIAC REGION EPIGASTRIC REGION RIGHT LUMBAR REGION UMBILICAL REGION RIGHT INGUINAL REGION HYPOGASTRIC REGION HYPOGASTRIC REGION (a) Anterior view showing abdominopelvic regions LEFT HYPOCHONDRIAC REGION LEFT LUMBAR REGION LEFT INGUINAL REGION Subcostal line Right Clavicles Clavicles Left Midclavicular lines Midclavicular lines Transtubercular line RIGHT HYPOCHONDRIAC REGION EPIGASTRIC REGION RIGHT LUMBAR REGION LEFT LUMBAR REGION UMBILICAL REGION RIGHT INGUINAL REGION LEFT INGUINAL REGION (b) Anterior view showing location of abdominopelvic regions Right Left LEFT HYPOCHONDRIAC REGION HYPOGASTRIC REGION RIGHT UPPER QUADRANT (RUQ) RIGHT LOWER QUADRANT (RLQ) LEFT UPPER QUADRANT (LUQ) Median line LEFT LOWER QUADRANT (LLQ) Transumbilical line (c) Anterior view showing location of abdominopelvic quadrants JWCL316_c01_001-028.qxd 06/10/2010 23:22 Page 20
  • The names of the nine abdominopelvic regions are right hypochondriac (hı¯Ј-po¯-KON-dre¯-ak), epigastric (ep-i-GAS- trik), left hypochondriac, right lumbar, umbilical (um-BIL-i- kal) left lumbar, right inguinal (iliac) (IN-gwi-nal), hypogas- tric (pubic), and left inguinal (iliac). The second method is simpler and divides the abdominopelvic cavity into quadrants (KWOD-rantz; quad- ϭ one-fourth), as shown in Figure 1.12c. In this method, a midsagittal line (the me- dian line) and a transverse line (the transumbilical line) are passed through the umbilicus (um-BI-li-kus; umbilic- ϭ navel) or belly button. The names of the abdominopelvic quadrants are right up- per quadrant (RUQ), left upper quadrant (LUQ), right lower quadrant (RLQ), and left lower quadrant (LLQ). The nine- region division is more widely used for anatomical studies, and quadrants are more commonly used by clinicians for describing the site of abdominopelvic pain, a tumor, or another abnormality. C H E C K P O I N T 12. Locate each region shown in Figure 1.5 on your own body, and then identify it by its anatomical name and the corresponding common name. 13. What structures separate the various body cavities from one another? 14. Locate the nine abdominopelvic regions and the four abdominopelvic quadrants on yourself, and list some of the organs found in each. 1.6 MEDICAL IMAGING O B J E C T I V E • Describe the principles and importance of medical imaging procedures in the evaluation of organ functions and the diagnosis of disease. Medical imaging refers to techniques and procedures used to create images of the human body. Various types of medical imag- ing allow visualization of structures inside our bodies and are in- creasingly helpful for precise diagnosis of a wide range of anatomical and physiological disorders. The grandparent of all medical imaging techniques is conventional radiography (x-rays), in medical use since the late 1940s. The newer imaging technolo- gies not only contribute to diagnosis of disease, but they also are advancing our understanding of normal anatomy and physiology. Table 1.3 describes some commonly used medical imaging tech- niques. Other imaging methods, such as cardiac catheterization, will be discussed in later chapters. C H E C K P O I N T 15. Which forms of medical imaging would be used to show a blockage in an artery of the heart? 16. Of the medical imaging techniques outlined in Table 1.3, which one best reveals the physiology of a structure? 17. Which medical imaging technique would you use to determine whether a bone was broken? 1.6 MEDICAL IMAGING 21 RADIOGRAPHY Procedure: A single barrage of x-rays passes through the body, producing an image of interior structures on x-ray–sensitive film. The resulting two- dimensional image is a radiograph (RA¯-de¯-o¯-grafЈ), commonly called an x-ray. Comments: Relatively inexpensive, quick, and simple to perform; usually provides sufficient information for diagnosis. X-rays do not easily pass through dense structures, so bones appear white. Hollow structures, such as the lungs, appear black. Structures of intermediate density, such as skin, fat, and muscle, appear as varying shades of gray. At low doses, x-rays are useful for examining soft tissues such as the breast (mammography) and for determining bone density (bone densitometry). Left clavicle Rib Left lung Heart Radiograph of the thorax in anterior view Mammogram of a female breast showing a cancerous tumor (white mass with uneven border) Bone densitometry scan of the lumbar spine in anterior view TABLE 1.3 Common Medical Imaging Procedures TABLE 1.3 CONTINUES JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 21
  • 22 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY TABLE 1.3 CONTINUED Common Medical Imaging Procedures MAGNETIC RESONANCE IMAGING (MRI) Procedure: The body is exposed to a high-energy magnetic field, which causes protons (small positive particles within atoms, such as hydrogen) in body fluids and tissues to arrange themselves in relation to the field. Then a pulse of radio waves “reads” these ion patterns, and a color-coded image is assembled on a video monitor. The result is a two- or three-dimensional blueprint of cellular chemistry. Comments: Relatively safe, but cannot be used on patients with metal in their bodies. Shows fine details for soft tissues but not for bones. Most useful for differentiating between normal and abnormal tissues. Used to detect tumors and artery-clogging fatty plaques; reveal brain abnormalities; measure blood flow; and detect a variety of musculoskeletal, liver, and kidney disorders. Magnetic resonance image of the brain in sagittal section Angiogram of an adult human heart showing a blockage in a coronary artery (arrow) Intravenous urogram showing a kidney stone (arrow) in the right kidney Barium contrast x-ray showing a cancer of the ascending colon (arrow) RADIOGRAPHY (CONTINUED) It is necessary to use a substance called a contrast medium to make hollow or fluid-filled structures visible (appear white) in radiographs. X-rays make structures that contain contrast media appear white. The medium may be introduced by injection, orally, or rectally, depending on the structure to be imaged. Contrast x-rays are used to image blood vessels (angiography), the urinary system (intravenous urography), and the gastrointestinal tract (barium contrast x-ray). DIFFUSION TENSOR IMAGING (DTI) Procedure: Diffusion tensor imaging (DTI) is a variation of MRI that tracks the movement of water molecules along the length of axons, long processes of nerve cells that form the white matter in the brain. The white matter is organized into bundles of axons called tracts that connect one part of the brain with another. DTI provides images of the brain’s white matter. Comments: Used in the diagnosis of addictions, epilepsy, brain tumors, traumatic brain injury, stroke, multiple sclerosis, and neurodegenerative diseases. Diffusion tensor image of transverse section of the brain showing white matter (various colors) JWCL316_c01_001-028.qxd 7/27/10 5:36 PM Page 22
  • 1.6 MEDICAL IMAGING 23 TABLE 1.3 CONTINUES COMPUTED TOMOGRAPHY (CT) [formerly called computerized axial tomography (CAT) scanning] Procedure: In this form of computer-assisted radiography, an x-ray beam traces an arc at multiple angles around a section of the body. The resulting transverse section of the body, called a CT scan, is shown on a video monitor. Comments: Visualizes soft tissues and organs with much more detail than conventional radiographs. Differing tissue densities show up as various shades of gray. Multiple scans can be assembled to build three-dimensional views of structures (described next). Whole-body CT scanning typically targets the torso and appears to provide the most benefit in screening for lung cancers, coronary artery disease, and kidney cancers. ANTERIOR Heart Backbone Left rib Left scapula Aorta Computed tomography scan of the thorax in inferior view POSTERIOR CORONARY (CARDIAC) COMPUTED TOMOGRAPHY ANGIOGRAPHY (CCTA) SCAN Procedure: In this form of computer-assisted radiography, an iodine- containing contrast medium is injected into a vein and a beta-blocker is given to decrease heart rate. Then, numerous x-ray beams trace an arc around the heart and a scanner detects the x-ray beams and transmits them to a computer, which transforms the information into a three-dimensional image of the coronary blood vessels on a monitor. The image produced is called a CCTA scan and can be generated in less than 20 seconds. Comments: Used primarily to determine if there are any coronary artery blockages (for example, atherosclerotic plaque or calcium) that may require an intervention such as angioplasty or stent. The CCTA scan can be rotated, enlarged, and moved at any angle. The procedure can take thousands of images of the heart within the time of a single heartbeat, so it provides a great amount of detail about the heart’s structure and function. CCTA scan of coronary arteries Normal left coronary artery Blocked right coronary artery ULTRASOUND SCANNING Procedure: High-frequency sound waves produced by a handheld wand reflect off body tissues and are detected by the same instrument. The image, which may be still or moving, is called a sonogram (SON-o¯-gram) and is shown on a video monitor. Comments: Safe, noninvasive, painless, and uses no dyes. Most commonly used to visualize the fetus during pregnancy. Also used to observe the size, location, and actions of organs and blood flow through blood vessels (Doppler ultrasound). Forehead Eye Hand Sonogram of a fetus (Courtesy of Andrew Joseph Tortora and Damaris Soler) JWCL316_c01_001-028.qxd 7/27/10 5:36 PM Page 23
  • 24 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY TABLE 1.3 CONTINUED Common Medical Imaging Procedures POSITRON EMISSION TOMOGRAPHY (PET) Procedure: A substance that emits positrons (positively charged particles) is injected into the body, where it is taken up by tissues. The collision of positrons with negatively charged electrons in body tissues produces gamma rays (similar to x-rays) that are detected by gamma cameras positioned around the subject. A computer receives signals from the gamma cameras and constructs a PET scan image, displayed in color on a video monitor. The PET scan shows where the injected substance is being used in the body. In the PET scan image shown here, the black and blue colors indicate minimal activity; the red, orange, yellow, and white colors indicate areas of increasingly greater activity. Comments: Used to study the physiology of body structures, such as metabolism in the brain or heart. POSTERIOR ANTERIOR Positron emission tomography scan of a transverse section of the brain (circled area at upper left indicates where a stroke has occurred) ENDOSCOPY Procedure: Endoscopy involves the visual examination of the inside of body organs or cavities using a lighted instrument with lenses called an endoscope. The image is viewed through an eyepiece on the endoscope or projected onto a monitor. Comments: Examples include colonoscopy (used to examine the interior of the colon, which is part of the large intestine), laparoscopy (used to examine the organs within the abdominopelvic cavity), and arthroscopy (used to examine the interior of a joint, usually the knee). Interior view of the colon as shown by colonoscopy RADIONUCLIDE SCANNING Procedure: A radionuclide (radioactive substance) is introduced intravenously into the body and carried by the blood to the tissue to be imaged. Gamma rays emitted by the radionuclide are detected by a gamma camera outside the subject, and the data are fed into a computer. The computer constructs a radionuclide image and displays it in color on a video monitor. Areas of intense color take up a lot of the radionuclide and represent high tissue activity; areas of less intense color take up smaller amounts of the radionuclide and represent low tissue activity. Single-photon-emission computerized tomography (SPECT) scanning is a specialized type of radionuclide scanning that is especially useful for studying the brain, heart, lungs, and liver. Comments: Used to study activity of a tissue or organ, such as searching for malignant tumors in body tissue or scars that may interfere with heart muscle activity. Radionuclide (nuclear) scan of a normal human heart Single-photon-emission computerized tomography (SPECT) scan of a transverse section of the brain (green area at lower left indicates a migraine attack) JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 24
  • CHAPTER REVIEW AND RESOURCE SUMMARY 25 CHAPTER REVIEW AND RESOURCE SUMMARY 1.1 Anatomy and Physiology Defined 1. Anatomy is the science of body structures and the relationships among structures; physiology is the science of body functions. 2. Dissection is the careful cutting apart of body structures to study their relationships. 3. Some subspecialties of anatomy are embryology, developmental biology, cell biology, histology, gross anatomy, systemic anatomy, regional anatomy, surface anatomy, radiographic anatomy, and patholog- ical anatomy (see Table 1.1). 4. Some subspecialties of physiology are neurophysiology, endocrinology, cardiovascular physiology, immunology, respiratory physiology, renal physiology, exercise physiology, and pathophysiology (see Table 1.1). 1.2 Levels of Structural Organization and Body Systems 1. The human body consists of six levels of structural organization: chemical, cellular, tissue, organ, sys- tem, and organismal. 2. Cells are the basic structural and functional living units of an organism and the smallest living units in the human body. 3. Tissues are groups of cells and the materials surrounding them that work together to perform a par- ticular function. 4. Organs are composed of two or more different types of tissues; they have specific functions and usu- ally have recognizable shapes. 5. Systems consist of related organs that have a common function. 6. An organism is any living individual. 7. Table 1.2 introduces the 11 systems of the human organism: the integumentary, skeletal, muscular, nerv- ous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive systems. 1.3 Characteristics of the Living Human Organism 1. All organisms carry on certain processes that distinguish them from nonliving things. 2. Among the life processes in humans are metabolism, responsiveness, movement, growth, differentia- tion, and reproduction. 1.4 Homeostasis 1. Homeostasis is a condition of equilibrium in the body’s internal environment produced by the inter- play of all the body’s regulatory processes. 2. Body fluids are dilute, watery solutions. Intracellular fluid (ICF) is inside cells, and extracellular fluid (ECF) is outside cells. Plasma is the ECF within blood vessels. Interstitial fluid is the ECF that fills spaces between tissue cells; because it surrounds all body cells, interstitial fluid is called the body’s internal environment. 3. Disruptions of homeostasis come from external and internal stimuli and psychological stresses. When disruption of homeostasis is mild and temporary, responses of body cells quickly restore balance in the internal environment. If disruption is extreme, regulation of homeostasis may fail. 4. Most often, the nervous and endocrine systems acting together or separately regulate homeostasis. The nervous system detects body changes and sends nerve impulses to counteract changes in controlled conditions. The endocrine system regulates homeostasis by secreting hormones. 5. Feedback systems include three components: (1) Receptors monitor changes in a controlled condition and send input to a control center (afferent pathway). (2) The control center sets the value (set point) at which a controlled condition should be maintained, evaluates the input it receives from receptors (efferent pathway), and generates output commands when they are needed. (3) Effectors receive out- put from the control center and produce a response (effect) that alters the controlled condition. 6. If a response reverses the original stimulus, the system is operating by negative feedback. If a response enhances the original stimulus, the system is operating by positive feedback. 7. One example of negative feedback is the regulation of blood pressure. If a stimulus causes blood pres- sure (controlled condition) to rise, baroreceptors (pressure-sensitive nerve cells, the receptors) in blood vessels send impulses (input) to the brain (control center). The brain sends impulses (output) to the heart (effector). As a result, heart rate decreases (response) and blood pressure decreases to normal (restoration of homeostasis). Anatomy Overview - The Integumentary System Anatomy Overview - The Skeletal System Anatomy Overview - The Muscular System Anatomy Overview - The Nervous System Anatomy Overview -The Endocrine System Anatomy Overview - The Cardiovascular System Anatomy Overview - The Lymphatic and Immune Systems Anatomy Overview - The Respiratory System Anatomy Overview - The Digestive System Anatomy Overview - The Urinary System Anatomy Overview - The Reproductive Systems Exercise - Concentrate on Systemic Functions Exercise - Find the System Outsiders Review Resource Animation - Communication, Regulation, and Homeostasis Animation - Communication, Regulation, and Homeostasis Animation - Homeostatic Relationships Animation - Negative Feedback Control of Blood Pressure Animation - Negative Feedback Control of Temperature Animation - Positive Feedback Control of Labor Exercise - System Contributions to Body Homeostasis Concepts and Connections - Negative Feedback Loop Concepts and Connections - Regulation and Communication JWCL316_c01_001-028.qxd 02/09/2010 23:09 Page 25
  • 26 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY Review Resource 8. One example of positive feedback occurs during the birth of a baby. When labor begins, the cervix of the uterus is stretched (stimulus), and stretch-sensitive nerve cells in the cervix (receptors) send nerve impulses (input) to the brain (control center). The brain responds by releasing oxytocin (output), which stimulates the uterus (effector) to contract more forcefully (response). Movement of the fetus further stretches the cervix, more oxytocin is released, and even more forceful contractions occur. The cycle is broken with the birth of the baby. 9. Disruptions of homeostasis—homeostatic imbalances—can lead to disorders, diseases, and even death. A disorder is a general term for any abnormality of structure or function. A disease is an illness with a definite set of signs and symptoms. 10. Symptoms are subjective changes in body functions that are not apparent to an observer; signs are objective changes that can be observed and measured. 1.5 Basic Anatomical Terminology 1. Descriptions of any region of the body assume the body is in the anatomical position, in which the subject stands erect facing the observer, with the head level and the eyes facing directly forward. The feet are flat on the floor and directed forward, and the upper limbs are at the sides, with the palms turned forward. A body lying facedown is prone; a body lying faceup is supine. 2. Regional names are terms given to specific regions of the body. The principal regions are the head, neck, trunk, upper limbs, and lower limbs. Within the regions, specific body parts have anatomical names and corresponding common names. Examples are thoracic (chest), nasal (nose), and carpal (wrist). 3. Directional terms indicate the relationship of one part of the body to another. Exhibit 1.A summarizes commonly used directional terms. 4. Planes are imaginary flat surfaces that are used to divide the body or organs to visualize interior struc- tures. A midsagittal plane divides the body or an organ into equal right and left sides. A parasagittal plane divides the body or an organ into unequal right and left sides. A frontal plane divides the body or an organ into anterior and posterior portions. A transverse plane divides the body or an organ into superior and inferior portions. An oblique plane passes through the body or an organ at an oblique angle. 5. Sections are cuts of the body or its organs made along a plane. They are named according to the plane along which the cut is made and include transverse, frontal, and sagittal sections. 6. Figure 1.9 summarizes body cavities and their membranes. Body cavities are spaces in the body that help protect, separate, and support internal organs. The cranial cavity contains the brain, and the ver- tebral canal contains the spinal cord. The meninges are protective tissues that line the cranial cavity and vertebral canal. The diaphragm separates the thoracic cavity from the abdominopelvic cavity. Vis- cera are organs within the thoracic and abdominopelvic cavities. A serous membrane lines the wall of the cavity and adheres to the viscera. 7. The thoracic cavity is subdivided into three smaller cavities: a pericardial cavity, which contains the heart, and two pleural cavities, each of which contains a lung. The central part of the thoracic cavity is an anatomical region called the mediastinum. It is located between the pleural cavities, extending from the sternum to the vertebral column and from the first rib to the diaphragm. It contains all tho- racic viscera except the lungs. 8. The abdominopelvic cavity is divided into a superior abdominal and an inferior pelvic cavity. Viscera of the abdominal cavity include the stomach, spleen, liver, gallbladder, small intestine, and most of the large intestine. Viscera of the pelvic cavity include the urinary bladder, portions of the large intestine, and internal organs of the reproductive system. 9. Serous membranes line the walls of the thoracic and abdominal cavities and cover the organs within them. They include the pleura, associated with the lungs; the pericardium, associated with the heart; and the peritoneum, associated with the abdominal cavity. 10. To describe the location of organs more easily, the abdominopelvic cavity is divided into nine regions: right hypochondriac, epigastric, left hypochondriac, right lumbar, umbilical, left lumbar, right inguinal (iliac), hypogastric (pubic), and left inguinal (iliac). To locate the site of an abdominopelvic abnormal- ity in clinical studies, the abdominopelvic cavity is divided into quadrants: right upper quadrant (RUQ), left upper quadrant (LUQ), right lower quadrant (RLQ), and left lower quadrant (LLQ). 1.6 Medical Imaging 1. Medical imaging refers to techniques and procedures used to create images of the human body. They allow visualization of internal structures to diagnose abnormal anatomy and deviations from normal physiology. 2. Table 1.3 summarizes and illustrates several medical imaging techniques. Anatomy Overview - Serous Membrane Figure 1.5 - The Anatomical Position Figure 1.6 - Directional Terms Figure 1.9 - Body Cavities Figure 1.10 - The Thoracic Cavity JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 26
  • SELF-QUIZ QUESTIONS 27 13. Choose the term that best fits the blank in each statement. Some answers may be used more than once. (a) Your eyes are to your chin. (b) Your skin is to your heart. (c) Your right shoulder is and from your umbili- cus (belly button). (d) In the anatomical position, your thumb is . (e) Your buttocks are . (f) Your right foot and right hand are . (g) Your knee is between your thigh and toes. (h) Your lungs are to your spinal column. (i) Your breastbone is _____ to your chin. (j) Your calf is _____ to your heel. 14. Match the following cavities to their definitions: (a) a fluid-filled space that surrounds the heart (b) the cavity that contains the brain (c) a cavity formed by the ribs, muscles of the chest, sternum, and part of the vertebral column (d) a cavity that contains the stom- ach, spleen, liver, gallbladder, small intestine, and most of the large intestine (e) fluid-filled space that surrounds a lung (f) the cavity that contains the uri- nary bladder, part of the large intestine, and the organs of the reproductive system (g) the canal that contains the spinal cord Fill in the blanks in the following statements. 1. A(n) is a group of similar cells and their surrounding mate- rials performing specific functions. 2. The sum of all of the body’s chemical processes is . It con- sists of two parts: the phase that builds up new substances is , and the phase that breaks down substances is . 3. The fluid located within cells is the , whereas the fluid located outside of the cells is . Indicate whether the following statements are true or false. 4. In a positive feedback system, the response enhances or intensifies the original stimulus. 5. A person lying face down would be in the supine position. 6. The highest level of structural organization is the system level. Choose the one best answer to the following questions. 7. A plane that separates the body into unequal right and left sides is a (a) transverse plane (b) frontal plane (c) midsagittal plane (d) coronal plane (e) parasagittal plane 8. Midway through a 5-mile workout, a runner begins to sweat pro- fusely. The sweat glands producing the sweat would be considered which part of a feedback loop? (a) controlled condition (b) receptors (c) stimulus (d) effectors (e) control center 9. An unspecialized stem cell becomes a brain cell during fetal devel- opment. This is an example of (a) differentiation (b) growth (c) organization (d) responsiveness (e) homeostasis. 10. A radiography technician needs to x-ray a growth on the urinary bladder. To accomplish this, the camera must be positioned on the region. (a) left inguinal (b) epigastric (c) hypogastric (d) right inguinal (e) umbilical 11. Which of the following would not be associated with the thoracic cavity? (1) pericardium, (2) mediastinum, (3) peritoneum, (4) pleura, (a) 2 and 3 (b) 2 (c) 3 (d) 1 and 4 (e) 3 and 4 12. Match the following common names and anatomical descriptive ad- jectives: (a) axillary (b) inguinal (c) cervical (d) cranial (e) oral (f) brachial (g) orbital (h) gluteal (i) buccal (j) coxal SELF-QUIZ QUESTIONS (1) cranial cavity (2) vertebral canal (3) thoracic cavity (4) pericardial cavity (5) pleural cavity (6) abdominal cavity (7) pelvic cavity (1) skull (2) eye (3) cheek (4) armpit (5) arm (6) groin (7) buttock (8) neck (9) mouth (10) hip (1) superior (2) inferior (3) anterior (4) posterior (5) medial (6) lateral (7) intermediate (8) ipsilateral (9) contralateral (10) proximal (11) distal (12) superficial (13) deep JWCL316_c01_001-028.qxd 7/1/10 5:36 AM Page 27
  • 28 CHAPTER 1 • AN INTRODUCTION TO THE HUMAN BODY (1) regulates body activities through hormones (chemicals) transported in the blood to various target organs of the body (2) produces gametes; releases hormones from gonads (3) protects against disease; returns fluids to blood (4) protects body by forming a barrier to the outside environment; helps regulate body temperature (5) transports oxygen and nutrients to cells; protects against disease; carries wastes away from cells (6) regulates body activities through action potentials (nerve impulses); receives sensory information; in- terprets and responds to the information (7) carries out the physical and chemical breakdown of food and absorption of nutrients (8) transfers oxygen and carbon dioxide between air and blood (9) supports and protects the body; provides internal framework; provides a place for muscle attachment (10) powers movements of the body and stabilizes body position (11) eliminates wastes; regulates the volume and chemical composition of blood 15. Match the following systems with their functions: (a) nervous system (b) endocrine system (c) urinary system (d) cardiovascular system (e) muscular system (f) respiratory system (g) digestive system (h) skeletal system (i) integumentary system (j) lymphatic system and immunity (k) reproductive system CRITICAL THINKING QUESTIONS some of the normal cells in the pancreas. What would make stem cells useful in disease treatment? 3. On her first anatomy and physiology exam, Heather defined home- ostasis as “the condition in which the body approaches room tem- perature and stays there.” Do you agree with Heather’s definition? 1. You are studying for your first anatomy and physiology exam and want to know which areas of your brain are working hardest as you study. Your classmate suggests that you could have a computed to- mography (CT) scan done to assess your brain activity. Would this be the best way to determine brain activity levels? 2. There is much interest in using stem cells to help in the treatment of diseases such as type I diabetes, which is due to a malfunction of 1.8 The parasagittal plane (not shown in the figure) divides the brain into unequal right and left portions. 1.9 Urinary bladder ϭ P, stomach ϭ A, heart ϭ T, small intestine ϭ A, lungs ϭ T, internal female reproductive organs ϭ P, thymus ϭ T, spleen ϭ A, liver ϭ A. 1.10 The pericardial cavity surrounds the heart, and the pleural cavities surround the lungs. 1.11 The illustrated abdominal cavity organs all belong to the digestive system (liver, gallbladder, stomach, small intestine, and most of the large intestine). Illustrated pelvic cavity organs belong to the urinary system (the urinary bladder) and the digestive system (part of the large intestine). 1.12 The liver is mostly in the epigastric region; the ascending colon is in the right lumbar region; the urinary bladder is in the hypogastric region; most of the small intestine is in the umbilical region. The pain associated with appendicitis would be felt in the right lower quadrant (RLQ). 1.1 Organs are composed of two or more different types of tissues that work together to perform a specific function. 1.2 The difference between negative and positive feedback systems is that in negative feedback systems, the response reverses the origi- nal stimulus, but in positive feedback systems, the response en- hances the original stimulus. 1.3 When something causes blood pressure to decrease, then heart rate increases due to operation of this negative feedback system. 1.4 Because positive feedback systems continually intensify or rein- force the original stimulus, some mechanism is needed to end the response. 1.5 Having one standard anatomical position allows directional terms to be clearly defined so that any body part can be described in rela- tion to any other part. 1.6 No, the radius is distal to the humerus. No, the esophagus is poste- rior to the trachea.Yes, the ribs are superficial to the lungs.Yes, the urinary bladder is medial to the ascending colon. No, the sternum is medial to the descending colon. 1.7 The frontal plane divides the heart into anterior and posterior portions. ANSWERS TO FIGURE QUESTIONS JWCL316_c01_001-028.qxd 7/27/10 5:36 PM Page 28
  • CHEMISTRY AND HOMEOSTASIS Maintaining the proper assortment and quantity of thou- sands of different chemicals in your body, and monitoring the interactions of these chemi- cals with one another, are two important aspects of homeostasis. 29 ? Did you ever wonder how fatty acids relate to health and disease? CO art to place per Dummier 2 THE CHEMICAL LEVEL OF ORGANIZATION ? G C G C TA A AT AT AT T C G C G You learned in Chapter 1 that the chemical level of organiza- tion, the lowest level of structural organization, consists of atoms and molecules. These letters of the anatomical alphabet ultimately combine to form body organs and systems of aston- ishing size and complexity. In this chapter, we consider how atoms bond together to form molecules, and how atoms and molecules release or store energy in processes known as chem- ical reactions. You will also learn about the vital importance of water, which accounts for nearly two-thirds of your body weight, in chemical reactions and the maintenance of home- ostasis. Finally, we present several groups of molecules whose unique properties contribute to assembly of your body’s struc- tures and to powering the processes that enable you to live. Chemistry (KEM-is-tre¯) is the science of the structure and interactions of matter. All living and nonliving things consist of matter, which is anything that occupies space and has mass. Mass is the amount of matter in any object, which does not change. Weight, the force of gravity acting on matter, does change. When objects are farther from Earth, the pull of grav- ity is weaker; this is why the weight of an astronaut is close to zero in outer space. JWCL316_c02_029-062.qxd 7/15/10 7:46 AM Page 29
  • 2.1 HOW MATTER IS ORGANIZED O B J E C T I V E S • Identify the main chemical elements of the human body. • Describe the structures of atoms, ions, molecules, free radicals, and compounds. Chemical Elements Matter exists in three states: solid, liquid, and gas. Solids, such as bones and teeth, are compact and have a definite shape and vol- ume. Liquids, such as blood plasma, have a definite volume and assume the shape of their container. Gases, like oxygen and car- bon dioxide, have neither a definite shape nor volume. All forms of matter—both living and nonliving—are made up of a limited number of building blocks called chemical elements. Each ele- ment is a substance that cannot be split into a simpler substance by ordinary chemical means. Scientists now recognize 117 ele- ments. Of these, 92 occur naturally on Earth. The rest have been produced from the natural elements using particle accelerators or nuclear reactors. Each element is designated by a chemical sym- bol, one or two letters of the element’s name in English, Latin, or another language. Examples of chemical symbols are H for hydrogen, C for carbon, O for oxygen, N for nitrogen, Ca for calcium, and Na for sodium (natrium ϭ sodium).* Twenty-six different chemical elements normally are present in your body. Just four elements, called the major elements, con- stitute about 96% of the body’s mass: oxygen, carbon, hydrogen, and nitrogen. Eight others, the lesser elements, contribute about 3.6% to the body’s mass: calcium, phosphorus (P), potassium (K), sulfur (S), sodium, chlorine (Cl), magnesium (Mg), and iron (Fe). An additional 14 elements—the trace elements—are present in tiny amounts. Together, they account for the remaining about 0.4% of the body’s mass. Several trace elements have im- portant functions in the body. For example, iodine is needed to make thyroid hormones. The functions of some trace elements are unknown. Table 2.1 lists the main chemical elements of the hu- man body. 30 CHAPTER 2 • THE CHEMICAL LEVEL OF ORGANIZATION *The periodic table of elements, which lists all of the known chemical elements, can be found in Appendix B. TABLE 2.1 Main Chemical Elements in the Body CHEMICAL ELEMENT % OF TOTAL (SYMBOL) BODY MASS SIGNIFICANCE MAJOR ELEMENTS (about 96) Oxygen (O) 65.0 Part of water and many organic (carbon-containing) molecules; used to generate ATP, a molecule used by cells to temporarily store chemical energy. Carbon (C) 18.5 Forms backbone chains and rings of all organic molecules: carbohydrates, lipids (fats), proteins, and nucleic acids (DNA and RNA). Hydrogen (H) 9.5 Constituent of water and most organic molecules; ionized form (Hϩ ) makes body fluids more acidic. Nitrogen (N) 3.2 Component of all proteins and nucleic acids. LESSER ELEMENTS (about 3.6) Calcium (Ca) 1.5 Contributes to hardness of bones and teeth; ionized form (Ca2ϩ ) needed for blood clotting, release of some hormones, contraction of muscle, and many other processes. Phosphorus (P) 1.0 Component of nucleic acids and ATP; required for normal bone and tooth structure. Potassium (K) 0.35 Ionized form (Kϩ ) is the most plentiful cation (positively charged particle) in intracellular fluid; needed to generate action potentials. Sulfur (S) 0.25 Component of some vitamins and many proteins. Sodium (Na) 0.2 Ionized form (Naϩ ) is the most plentiful cation in extracellular fluid; essential for maintaining water balance; needed to generate action potentials. Chlorine (Cl) 0.2 Ionized form (ClϪ ) is the most plentiful anion (negatively charged particle) in extracellular fluid; essential for maintaining water balance. Magnesium (Mg) 0.1 Ionized form (Mg2ϩ ) needed for action of many enzymes, molecules that increase the rate of chemical reactions in organisms. Iron (Fe) 0.005 Ionized forms (Fe2ϩ and Fe3ϩ ) are part of hemoglobin (oxygen-carrying protein in red blood cells) and some enzymes. TRACE ELEMENTS (about 0.4) Aluminum (Al), boron (B), chromium (Cr), cobalt (Co), copper (Cu), fluorine (F), iodine (I), manganese (Mn), molybdenum (Mo), selenium (Se), silicon (Si), tin (Sn), vanadium (V), and zinc (Zn). JWCL316_c02_029-062.qxd 7/16/10 9:55 AM Page 30
  • Structure of Atoms Each element is made up of atoms, the smallest units of matter that retain the properties and characteristics of the element. Atoms are extremely small. Two hundred thousand of the largest atoms would fit on the period at the end of this sentence. Hydro- gen atoms, the smallest atoms, have a diameter less than 0.1 nanometer (0.1 ϫ 10Ϫ9 m ϭ 0.0000000001 m), and the largest atoms are only five times larger. Dozens of different subatomic particles compose individual atoms. However, only three types of subatomic particles are im- portant for understanding the chemical reactions in the human body: protons, neutrons, and electrons (Figure 2.1). The dense central core of an atom is its nucleus. Within the nucleus are pos- itively charged protons (pϩ ) and uncharged (neutral) neutrons (n0 ). The tiny, negatively charged electrons (eϪ ) move about in a large space surrounding the nucleus. They do not follow a fixed path or orbit but instead form a negatively charged “cloud” that envelops the nucleus (Figure 2.1a). Even though their exact positions cannot be predicted, specific groups of electrons are most likely to move about within certain regions around the nucleus. These regions, called electron shells, are depicted as simple circles around the nucleus. Because each electron shell can hold a specific number of electrons, the electron 2.1 HOW MATTER IS ORGANIZED 31 shell model best conveys this aspect of atomic structure (Fig- ure 2.1b). The first electron shell (nearest the nucleus) never holds more than 2 electrons. The second shell holds a maximum of 8 electrons, and the third can hold up to 18 electrons. The electron shells fill with electrons in a specific order, beginning with the first shell. For example, notice in Figure 2.2 that sodium (Na), which has 11 electrons total, contains 2 electrons in the first shell, 8 elec- trons in the second shell, and 1 electron in the third shell. The most massive element present in the human body is iodine, which has a total of 53 electrons: 2 in the first shell, 8 in the second shell, 18 in the third shell, 18 in the fourth shell, and 7 in the fifth shell. The number of electrons in an atom of an element always equals the number of protons. Because each electron and proton carries one charge, the negatively charged electrons and the posi- tively charged protons balance each other. Thus, each atom is electrically neutral; its total charge is zero. Atomic Number and Mass Number The number of protons in the nucleus of an atom is an atom’s atomic number. Figure 2.2 shows that atoms of different ele- ments have different atomic numbers because they have different numbers of protons. For example, oxygen has an atomic number of 8 because its nucleus has 8 protons, and sodium has an atomic number of 11 because its nucleus has 11 protons. The mass number of an atom is the sum of its protons and neutrons. Because sodium has 11 protons and 12 neutrons, its mass number is 23 (Figure 2.2). Although all atoms of one element have the same number of protons, they may have different num- bers of neutrons and thus different mass numbers. Isotopes are atoms of an element that have different numbers of neutrons and therefore different mass numbers. In a sample of oxygen, for example, most atoms have 8 neutrons, and a few have 9 or 10, but all have 8 protons and 8 electrons. Most isotopes are stable, which means that their nuclear structure does not change over time. The stable isotopes of oxygen are designated 16 O, 17 O, and 18 O (or O-16, O-17, and O-18). As you may already have determined, the numbers indicate the mass number of each isotope. As you will discover shortly, the number of electrons of an atom determines its chemical properties. Although the isotopes of an element have different numbers of neutrons, they have identical chemical prop- erties because they have the same number of electrons. Certain isotopes called radioactive isotopes are unstable; their nuclei decay (spontaneously change) into a stable configuration. Examples are H-3, C-14, O-15, and O-19. As they decay, these atoms emit radiation—either subatomic particles or packets of energy—and in the process often transform into a different ele- ment. For example, the radioactive isotope of carbon, C-14, de- cays to N-14. The decay of a radioisotope may be as fast as a frac- tion of a second or as slow as millions of years. The half-life of an isotope is the time required for half of the radioactive atoms in a sample of that isotope to decay into a more stable form. The half- life of C-14, which is used to determine the age of organic sam- ples, is about 5730 years; the half-life of I-131, an important clin- ical tool, is 8 days. Figure 2.1 Two representations of the structure of an atom. Electrons move about the nucleus, which contains neutrons and protons. (a) In the electron cloud model of an atom, the shading represents the chance of finding an electron in regions outside the nucleus. (b) In the electron shell model, filled circles represent individual electrons, which are grouped into concentric circles according to the shells they occupy. Both models depict a carbon atom, with six protons, six neutrons, and six electrons. An atom is the smallest unit of matter that retains the properties and characteristics of its element. How are the electrons of carbon distributed between the first and second electron shells? (a) Electron cloud model (b) Electron shell model Protons (p+) Neutrons (n0 ) Electrons (e– ) Nucleus JWCL316_c02_029-062.qxd 7/15/10 7:46 AM Page 31
  • Atomic Mass The standard unit for measuring the mass of atoms and their sub- atomic particles is a dalton, also known as an atomic mass unit (amu). A neutron has a mass of 1.008 daltons, and a proton has a mass of 1.007 daltons. The mass of an electron, at 0.0005 dalton, is almost 2000 times smaller than the mass of a neutron or proton. The atomic mass (also called the atomic weight) of an element is the average mass of all its naturally occurring isotopes. Typically, the atomic mass of an element is close to the mass number of its most abundant isotope. Ions, Molecules, and Compounds As we discussed, atoms of the same element have the same num- ber of protons. The atoms of each element have a characteristic way of losing, gaining, or sharing their electrons when interacting with other atoms to achieve stability. The way that electrons behave enables atoms in the body to exist in electrically charged forms called ions, or to join with each other into complex combi- nations called molecules. If an atom either gives up or gains elec- trons, it becomes an ion. An ion is an atom that has a positive or 32 CHAPTER 2 • THE CHEMICAL LEVEL OF ORGANIZATION Radioactive isotopes may have either harmful or helpful effects. Their radiations can break apart molecules, posing a serious threat to the human body by producing tissue damage and/or causing various types of cancer. Although the decay of naturally occurring radioactive isotopes typically releases just a small amount of radiation into the environment, localized accumulations can occur. Radon-222, a color- less and odorless gas that is a naturally occurring radioactive break- down product of uranium, may seep out of the soil and accumulate in buildings. It is not only associated with many cases of lung cancer in smokers but has also been implicated in many cases of lung cancer in nonsmokers. Beneficial effects of certain radioisotopes include their use in medical imaging procedures to diagnose and treat certain dis- orders. Some radioisotopes can be used as tracers to follow the movement of certain substances through the body. Thallium-201 is used to monitor blood flow through the heart during an exercise stress test. Iodine-131 is used to detect cancer of the thyroid gland and to assess its size and activity, and may also be used to destroy part of an overactive thyroid gland. Cesium-137 is used to treat advanced cervical cancer, and iridium-192 is used to treat prostate cancer. • CLINICAL CONNECTION | Harmful and Beneficial Effects of Radiation Figure 2.2 Atomic structures of several stable atoms. The atoms of different elements have different atomic numbers because they have different numbers of protons. Hydrogen (H) Atomic number = 1 Mass number = 1 or 2 Atomic mass = 1.01 Carbon (C) Atomic number = 6 Mass number = 12 or 13 Atomic mass = 12.01 Nitrogen (N) Atomic number = 7 Mass number = 14 or 15 Atomic mass = 14.01 Oxygen (O) Atomic number = 8 Mass number = 16, 17, or 18 Atomic mass = 16.00 Sodium (Na) Atomic number = 11 Mass number = 23 Atomic mass = 22.99 Chlorine (Cl) Atomic number = 17 Mass number = 35 or 37 Atomic mass = 35.45 Potassium (K) Atomic number = 19 Mass number = 39, 40, or 41 Atomic mass = 39.10 Iodine (I) Atomic number = 53 Mass number = 127 Atomic mass = 126.90 Second electron shell Third electron shell Fourth electron shell Atomic number = number of protons in an atom Mass number = number of protons and neutrons in an atom (boldface indicates most common isotope) Atomic mass = average mass of all stable atoms of a given element in daltons First electron shell 1p + 6p + 6n 0 8p + 8n 0 11p + 12n 0 17p + 18n 0 19p + 20n 0 Fifth electron shell 53p + 74n 0 7p + 7n 0 Which four of these elements are present most abundantly in living organisms? JWCL316_c02_029-062.qxd 7/15/10 7:46 AM Page 32
  • Oxygen molecule (O2)(a) Superoxide free radical (O2 –)(b) Unpaired electron O O O O – C H E C K P O I N T 1. List the names and chemical symbols of the 12 most abundant chemical elements in the human body. 2. What are the atomic number, mass number, and atomic mass of carbon? How are they related? 3. Define isotopes and free radicals. 2.2 CHEMICAL BONDS O B J E C T I V E S • Describe how valence electrons form chemical bonds. • Distinguish among ionic, covalent, and hydrogen bonds. The forces that hold together the atoms of a molecule or a com- pound are chemical bonds. The likelihood that an atom will form a chemical bond with another atom depends on the number of electrons in its outermost shell, also called the valence shell. An atom with a valence shell holding eight electrons is chemically stable, which means it is unlikely to form chemical bonds with other atoms. Neon, for example, has eight electrons in its valence shell, and for this reason it does not bond easily with other atoms. The valence shell of hydrogen and helium is the first electron shell, which holds a maximum of two electrons. Because helium has two valence electrons, it too is stable and seldom bonds with other atoms. Hydrogen, on the other hand, has only one valence electron (see Figure 2.2), so it binds readily with other atoms. The atoms of most biologically important elements do not have eight electrons in their valence shells. Under the right condi- tions, two or more atoms can interact in ways that produce a chemically stable arrangement of eight valence electrons for each atom. This chemical principle, called the octet rule (octet ϭ set of eight), helps explain why atoms interact in predictable ways. One atom is more likely to interact with another atom if doing so will leave both with eight valence electrons. For this to happen, an atom either empties its partially filled valence shell, fills it with donated electrons, or shares electrons with other atoms. The way that valence electrons are distributed determines what kind of chemical bond results. We will consider three types of chemical bonds: ionic bonds, covalent bonds, and hydrogen bonds. Ionic Bonds As you have already learned, when atoms lose or gain one or more valence electrons, ions are formed. Positively and nega- tively charged ions are attracted to one another—opposites 2.2 CHEMICAL BONDS 33 negative charge because it has unequal numbers of protons and electrons. Ionization is the process of giving up or gaining elec- trons. An ion of an atom is symbolized by writing its chemical symbol followed by the number of its positive (ϩ) or negative (–) charges. Thus, Ca2ϩ stands for a calcium ion that has two positive charges because it has lost two electrons. When two or more atoms share electrons, the resulting combi- nation is called a molecule (MOL-e-ku¯l). A molecular formula indicates the elements and the number of atoms of each element that make up a molecule. A molecule may consist of two atoms of the same kind, such as an oxygen molecule (Figure 2.3a). The molecular formula for a molecule of oxygen is O2. The subscript 2 indicates that the molecule contains two atoms of oxygen. Two or more different kinds of atoms may also form a molecule, as in a water molecule (H2O). In H2O one atom of oxygen shares elec- trons with two atoms of hydrogen. A compound is a substance that contains atoms of two or more different elements. Most of the atoms in the body are joined into compounds. Water (H2O) and sodium chloride (NaCl), common table salt, are compounds. However, a molecule of oxygen (O2) is not a compound because it consists of atoms of only one element. A free radical is an atom or group of atoms with an unpaired electron in the outermost shell.A common example is superoxide, which is formed by the addition of an electron to an oxygen molecule (Figure 2.3b). Having an unpaired electron makes a free radical unstable, highly reactive, and destructive to nearby molecules. Free radicals become stable by either giving up their unpaired electron to, or taking on an electron from, another molecule. In so doing, free radicals may break apart important body molecules. There are several sources of free radicals, including exposure to ultra- violet radiation in sunlight, exposure to x-rays, and some reactions that occur during normal metabolic processes. Certain harmful sub- stances, such as carbon tetrachloride (a solvent used in dry cleaning), also give rise to free radicals when they participate in metabolic reac- tions in the body. Among the many disorders, diseases, and condi- tions linked to oxygen-derived free radicals are cancer, atherosclero- sis, Alzheimer disease, emphysema, diabetes mellitus, cataracts, macular degeneration, rheumatoid arthritis, and deterioration asso- ciated with aging. Consuming more antioxidants—substances that inactivate oxygen-derived free radicals—is thought to slow the pace of damage caused by free radicals. Important dietary antioxidants in- clude selenium, zinc, beta-carotene, and vitamins C and E. Red, blue, or purple fruits and vegetables contain high levels of antioxidants. • CLINICAL CONNECTION | Free Radicals and Antioxidants Figure 2.3 Atomic structures of an oxygen molecule and a superoxide free radical. A free radical has an unpaired electron in its outermost electron shell. What substances in the body can inactivate oxygen-derived free radicals? JWCL316_c02_029-062.qxd 7/15/10 7:46 AM Page 33
  • attract. The force of attraction that holds together ions with oppo- site charges is an ionic bond. Consider sodium and chlorine atoms, the components of common table salt. Sodium has one va- lence electron (Figure 2.4a). If sodium loses this electron, it is left with the eight electrons in its second shell, which becomes the va- lence shell. As a result, however, the total number of protons (11) exceeds the number of electrons (10). Thus, the sodium atom has become a cation (KAT-ı¯-on), or positively charged ion. A sodium ion has a charge of 1ϩ and is written Naϩ . By contrast, chlorine has seven valence electrons (Figure 2.4b). If chlorine gains an electron from a neighboring atom, it will have a complete octet in its third electron shell. After gaining an electron, the total number of electrons (18) exceeds the number of protons (17), and the chlorine atom has become an anion (AN-ı¯-on), a negatively charged ion. The ionic form of chlorine is called a chloride ion. It has a charge of 1Ϫ and is written ClϪ . When an atom of sodium donates its sole valence electron to an atom of chlorine, the result- ing positive and negative charges pull both ions tightly together, forming an ionic bond (Figure 2.4c). The resulting compound is sodium chloride, written NaCl. In general, ionic compounds exist as solids, with an orderly, repeating arrangement of the ions, as in a crystal of NaCl (Fig- ure 2.4d). A crystal of NaCl may be large or small—the total number of ions can vary—but the ratio of Naϩ to ClϪ is always 1:1. In the body, ionic bonds are found mainly in teeth and bones, where they give great strength to these important structural tis- sues. An ionic compound that breaks apart into positive and neg- ative ions in solution is called an electrolyte (e-LEK-tro¯-lı¯t). Most ions in the body are dissolved in body fluids as electrolytes, so named because their solutions can conduct an electric current. (In Chapter 27 we will discuss the chemistry and importance of electrolytes.) Table 2.2 lists the names and symbols of common ions in the body. 34 CHAPTER 2 • THE CHEMICAL LEVEL OF ORGANIZATION Figure 2.4 Ions and ionic bond formation. (a) A sodium atom can have a complete octet of electrons in its outermost shell by losing one electron. (b) A chlorine atom can have a complete octet by gaining one electron. (c) An ionic bond may form between oppositely charged ions. (d) In a crystal of NaCl, each Naϩ is surrounded by six ClϪ . In (a), (b), and (c), the electron that is lost or accepted is colored red. An ionic bond is the force of attraction that holds together oppositely charged ions. Na Na (a) Sodium: 1 valence electron Atom Ion Electron donated Atom Ion (b) Chlorine: 7 valence electrons Electron accepted Cl Cl Na+ Cl – (d) Packing of ions in a crystal of sodium chloride (c) Ionic bond in sodium chloride (NaCl) ClNa What are cations and anions? TABLE 2.2 Common Ions in the Body CATIONS ANIONS NAME SYMBOL NAME SYMBOL Hydrogen ion Hϩ Fluoride ion FϪ Sodium ion Naϩ Chloride ion ClϪ Potassium ion Kϩ Iodide ion IϪ Ammonium ion NH4 ϩ Hydroxide ion OHϪ Magnesium ion Mg2ϩ Bicarbonate ion HCO3 Ϫ Calcium ion Ca2ϩ Oxide ion O2Ϫ Iron(II) ion Fe2ϩ Sulfate ion SO4 2Ϫ Iron(III) ion Fe3ϩ Phosphate ion PO4 3Ϫ JWCL316_c02_029-062.qxd 11/08/2010 09:19 Page 34
  • Covalent Bonds When a covalent bond forms, two or more atoms share electrons rather than gaining or losing them. Atoms form a covalently bonded molecule by sharing one, two, or three pairs of valence electrons. The larger the number of electron pairs shared between two atoms, the stronger the covalent bond. Covalent bonds may form between atoms of the same element or between atoms of different elements.They are the most common chemical bonds in the body, and the compounds that result from them form most of the body’s structures. A single covalent bond results when two atoms share one electron pair. For example, a molecule of hydrogen forms when two hydrogen atoms share their single valence electrons (Fig- ure 2.5a), which allows both atoms to have a full valence shell at 2.2 CHEMICAL BONDS 35 Figure 2.5 Covalent bond formation. The red electrons are shared equally in (a)–(d) and unequally in (e). In writing the structural formula of a covalently bonded molecule, each straight line between the chemical symbols for two atoms denotes a pair of shared electrons. In molecular formulas, the number of atoms in each molecule is noted by subscripts. In a covalent bond, two atoms share one, two, or three pairs of valence electrons. What is the principal difference between an ionic bond and a covalent bond? H Hydrogen atoms + O Oxygen atoms + Oxygen molecule Hydrogen molecule H H H H H H2 O O O O O O2 N Nitrogen atoms Hydrogen atoms + Nitrogen molecule N N N NN C Carbon atom + CH H H H Methane molecule H C CH4H H H O H2O H H STRUCTURAL FORMULA MOLECULAR FORMULA (a) DIAGRAMS OF ATOMIC AND MOLECULAR STRUCTURE (b) (c) (d) (e) H H H H Hydrogen atoms O Oxygen atom O Water molecule + H H H H δ+ δ+ δ– N2 JWCL316_c02_029-062.qxd 7/15/10 7:46 AM Page 35
  • least part of the time. A double covalent bond results when two atoms share two pairs of electrons, as happens in an oxygen mol- ecule (Figure 2.5b). A triple covalent bond occurs when two atoms share three pairs of electrons, as in a molecule of nitrogen (Figure 2.5c). Notice in the structural formulas for covalently bonded molecules in Figure 2.5 that the number of lines between the chemical symbols for two atoms indicates whether the bond is a single (O), double (P), or triple (q) covalent bond. The same principles of covalent bonding that apply to atoms of the same element also apply to covalent bonds between atoms of different elements. The gas methane (CH4) contains covalent bonds formed between the atoms of two different elements, one carbon and four hydrogens (Figure 2.5d). The valence shell of the carbon atom can hold eight electrons but has only four of its own. The single electron shell of a hydrogen atom can hold two electrons, but each hydrogen atom has only one of its own. A methane molecule contains four separate single covalent bonds. Each hydrogen atom shares one pair of electrons with the car- bon atom. In some covalent bonds, two atoms share the electrons equally—one atom does not attract the shared electrons more strongly than the other atom. This type of bond is a nonpolar covalent bond. The bonds between two identical atoms are always nonpolar covalent bonds (Figure 2.5a–c). The bonds between carbon and hydrogen atoms are also nonpolar, such as the four C—H bonds in a methane molecule (Figure 2.5d). In a polar covalent bond, the sharing of electrons between two atoms is unequal—the nucleus of one atom attracts the shared electrons more strongly than the nucleus of the other atom. When polar covalent bonds form, the resulting molecule has a partial negative charge near the atom that attracts electrons more strongly. This atom has greater electronegativity, the power to attract electrons to itself. At least one other atom in the molecule then will have a partial positive charge. The partial charges are indicated by a lowercase Greek delta with a minus or plus sign: ␦Ϫ or ␦ϩ . A very important example of a polar cova- lent bond in living systems is the bond between oxygen and hy- drogen in a molecule of water (Figure 2.5e); in this molecule, the nucleus of the oxygen atom attracts the electrons more strongly than do the nuclei of the hydrogen atoms, so the oxygen atom is said to have greater electronegativity. Later in the chapter, we will see how polar covalent bonds allow water to dissolve many molecules that are important to life. Bonds between nitrogen and hydrogen and those between oxygen and carbon are also polar bonds. Hydrogen Bonds The polar covalent bonds that form between hydrogen atoms and other atoms can give rise to a third type of chemical bond, a hydrogen bond (Figure 2.6). A hydrogen bond forms when a hydrogen atom with a partial positive charge (␦ϩ ) attracts the partial negative charge (␦Ϫ ) of neighboring electronegative atoms, most often larger oxygen or nitrogen atoms. Thus, hydrogen bonds result from attraction of oppositely charged parts of molecules rather than from sharing of electrons as in covalent bonds, or the loss or gain of electrons as in ionic bonds. Hydrogen bonds are weak compared to ionic and covalent bonds. Thus, they cannot bind atoms into molecules. However, hydrogen bonds do establish important links between molecules or between different parts of a large molecule, such as a protein or nucleic acid (both discussed later in this chapter). The hydrogen bonds that link neighboring water molecules give water considerable cohesion, the tendency of like particles to stay together. The cohesion of water molecules creates a very high surface tension, a measure of the difficulty of stretching or breaking the surface of a liquid. At the boundary between water and air, water’s surface tension is very high because the water molecules are much more attracted to one another than they are attracted to molecules in the air. This is readily seen when a spider walks on water or a leaf floats on water. The influence of water’s surface tension on the body can be seen in the way it increases the work required for breathing. A thin film of watery fluid coats the air sacs of the lungs. So, each inhalation must have enough force to overcome the opposing effect of surface tension as the air sacs stretch and enlarge when taking in air. Even though single hydrogen bonds are weak, very large mol- ecules may contain thousands of these bonds. Acting collectively, hydrogen bonds provide considerable strength and stability and help determine the three-dimensional shape of large molecules. As you will see later in this chapter, a large molecule’s shape determines how it functions. 36 CHAPTER 2 • THE CHEMICAL LEVEL OF ORGANIZATION Figure 2.6 Hydrogen bonding among water molecules. Each water molecule forms hydrogen bonds (indicated by dotted lines) with three to four neighboring water molecules. Hydrogen bonds occur because hydrogen atoms in one water molecule are attracted to the partial negative charge of the oxygen atom in another water molecule. Why would you expect ammonia (NH3) to form hydrogen bonds with water molecules? Hydrogen bonds δ+ δ+ δ– H H O JWCL316_c02_029-062.qxd 7/15/10 7:46 AM Page 36
  • C H E C K P O I N T 4. Which electron shell is the valence shell of an atom, and what is its significance? 5. Compare the properties of ionic, covalent, and hydrogen bonds. 6. What information is conveyed when you write the molecular or structural formula for a molecule? 2.3 CHEMICAL REACTIONS O B J E C T I V E S • Define a chemical reaction. • Describe the various forms of energy. • Compare exergonic and endergonic chemical reactions. • Describe the role of activation energy and catalysts in chemical reactions. • Describe synthesis, decomposition, exchange, and reversible reactions. A chemical reaction occurs when new bonds form or old bonds break between atoms. Chemical reactions are the foundation of all life processes, and as we have seen, the interactions of valence electrons are the basis of all chemical reactions. Consider how hydrogen and oxygen molecules react to form water molecules (Figure 2.7). The starting substances—two H2 and one O2—are known as the reactants. The ending substances—two molecules of H2O—are the products. The arrow in the figure indicates the direction in which the reaction proceeds. In a chemical reaction, the total mass of the reactants equals the total mass of the prod- ucts. Thus, the number of atoms of each element is the same before and after the reaction. However, because the atoms are rearranged, the reactants and products have different chemical properties. Through thousands of different chemical reactions, body structures are built and body functions are carried out. The term metabolism refers to all the chemical reactions occurring in the body. Forms of Energy and Chemical Reactions Each chemical reaction involves energy changes. Energy (en- ϭ in; -ergy ϭ work) is the capacity to do work. Two principal forms of energy are potential energy, energy stored by matter due to its position, and kinetic energy, the energy associated with mat- ter in motion. For example, the energy stored in water behind a dam or in a person poised to jump down some steps is potential energy. When the gates of the dam are opened or the person jumps, potential energy is converted into kinetic energy. Chemi- cal energy is a form of potential energy that is stored in the bonds of compounds and molecules. The total amount of energy present at the beginning and end of a chemical reaction is the same. Although energy can be neither created nor destroyed, it may be converted from one form to another. This principle is known as the law of conservation of energy. For example, some of the chemical energy in the foods we eat is eventually converted into various forms of kinetic energy, such as mechanical energy used to walk and talk. Conversion of energy from one form to another generally releases heat, some of which is used to maintain normal body temperature. Energy Transfer in Chemical Reactions Chemical bonds represent stored chemical energy, and chemical reactions occur when new bonds are formed or old bonds are bro- ken between atoms. The overall reaction may either release en- ergy or absorb energy. Exergonic reactions (ex- ϭ out) release more energy than they absorb. By contrast, endergonic reactions (end- ϭ within) absorb more energy than they release. A key feature of the body’s metabolism is the coupling of exergonic reactions and endergonic reactions. Energy released from an exergonic reaction often is used to drive an endergonic one. In general, exergonic reactions occur as nutrients, such as glucose, are broken down. Some of the energy released may be trapped in the covalent bonds of adenosine triphosphate (ATP), which we describe more fully later in this chapter. If a molecule of glucose is completely broken down, the chemical energy in its bonds can be used to produce as many as 38 molecules of ATP. The energy transferred to the ATP molecules is then used to drive endergonic reactions needed to build body structures, such as muscles and bones. The energy in ATP is also used to do the mechanical work involved in the contraction of muscle or the movement of substances into or out of cells. Activation Energy Because particles of matter such as atoms, ions, and molecules have kinetic energy, they are continuously moving and colliding with one another. A sufficiently forceful collision can disrupt the movement of valence electrons, causing an existing chemical bond to break or a new one to form. The collision energy needed to break the chemical bonds of the reactants is called the 2.3 CHEMICAL REACTIONS 37 Figure 2.7 The chemical reaction between two hydrogen molecules (H2) and one oxygen molecule (O2) to form two molecules of water (H2O). Note that the reaction occurs by breaking old bonds and making new bonds. The number of atoms of each element is the same before and after a chemical reaction. Why does this reaction require two molecules of H2? H H H H O O O H H O H H 2 H2 O2 2 H2O Reactants Products + JWCL316_c02_029-062.qxd 7/15/10 7:46 AM Page 37
  • activation energy of the reaction (Figure 2.8). This initial energy “investment” is needed to start a reaction. The reactants must ab- sorb enough energy for their chemical bonds to become unstable and their valence electrons to form new combinations. Then, as new bonds form, energy is released to the surroundings. Both the concentration of particles and the temperature influ- ence the chance that a collision will occur and cause a chemical reaction. • Concentration. The more particles of matter present in a confined space, the greater the chance that they will collide (think of people crowding into a subway car at rush hour). The concentration of particles increases when more are added to a given space or when the pressure on the space increases, which forces the particles closer together so that they collide more often. • Temperature. As temperature rises, particles of matter move about more rapidly. Thus, the higher the temperature of matter, the more forcefully particles will collide, and the greater the chance that a collision will produce a reaction. Catalysts As we have seen, chemical reactions occur when chemical bonds break or form after atoms, ions, or molecules collide with one an- other. Body temperature and the concentrations of molecules in body fluids, however, are far too low for most chemical reactions to occur rapidly enough to maintain life. Raising the temperature and the number of reacting particles of matter in the body could increase the frequency of collisions and thus increase the rate of chemical reactions, but doing so could also damage or kill the body’s cells. Substances called catalysts solve this problem. Catalysts are chemical compounds that speed up chemical reactions by lower- ing the activation energy needed for a reaction to occur (Fig- ure 2.9). The most important catalysts in the body are enzymes, which we will discuss later in this chapter. A catalyst does not alter the difference in potential energy between the reactants and the products. Rather, it lowers the amount of energy needed to start the reaction. For chemical reactions to occur, some particles of matter— especially large molecules—not only must collide with sufficient force, but they must hit one another at precise spots. A catalyst helps to properly orient the colliding particles. Thus, they interact at the spots that make the reaction happen. Although the action of a catalyst helps to speed up a chemical reaction, the catalyst itself is unchanged at the end of the reaction. A single catalyst molecule can assist one chemical reaction after another. Types of Chemical Reactions After a chemical reaction takes place, the atoms of the reactants are rearranged to yield products with new chemical properties. 38 CHAPTER 2 • THE CHEMICAL LEVEL OF ORGANIZATION Figure 2.8 Activation energy. Activation energy is the energy needed to break chemical bonds in the reactant molecules so a reaction can start. Why is the reaction illustrated here exergonic? Figure 2.9 Comparison of energy needed for a chemical reaction to proceed with a catalyst (blue curve) and without a catalyst (red curve). Catalysts speed up chemical reactions by lowering the activation energy. Does a catalyst change the potential energies of the products and reactants? Energy released as new bonds form Energy absorbed to start reaction Activation energy Progress of the reaction Potentialenergy Energy of reactants Energy of products Activation energy needed without catalyst Progress of the reaction Energy of products Energy of reactantsPotentialenergy Activation energy needed with catalyst JWCL316_c02_029-062.qxd 7/15/10 7:46 AM Page 38
  • In this section we will look at the types of chemical reactions common to all living cells. Once you have learned them, you will be able to understand the chemical reactions so important to the operation of the human body that are discussed throughout the book. Synthesis Reactions—Anabolism When two or more atoms, ions, or molecules combine to form new and larger molecules, the processes are called synthesis reactions. The word synthesis means “to put together.” A synthe- sis reaction can be expressed as follows: Combine to form A ϩ B AB Atom, ion, Atom, ion, New molecule AB or molecule A or molecule B One example of a synthesis reaction is the reaction between two hydrogen molecules and one oxygen molecule to form two molecules of water (see Figure 2.7). Another example of a syn- thesis reaction is the formation of ammonia from nitrogen and hydrogen: Combine to form N2 ϩ 3H2 2NH3 One nitrogen Three hydrogen Two ammonia molecule molecules molecules All the synthesis reactions that occur in your body are collec- tively referred to as anabolism (a-NAB-o¯-lizm). Overall, ana- bolic reactions are usually endergonic because they absorb more energy than they release. Combining simple molecules like amino acids (discussed shortly) to form large molecules such as proteins is an example of anabolism. Decomposition Reactions—Catabolism Decomposition reactions split up large molecules into smaller atoms, ions, or molecules. A decomposition reaction is expressed as follows: Breaks down into AB A ϩ B Molecule AB Atom, ion, or Atom, ion, molecule A or molecule B The decomposition reactions that occur in your body are col- lectively referred to as catabolism (ka-TAB-o¯-lizm). Overall, catabolic reactions are usually exergonic because they release more energy than they absorb. For instance, the series of reactions that break down glucose to pyruvic acid, with the net production of two molecules of ATP, are important catabolic reactions in the body. These reactions will be discussed in Chapter 25. Exchange Reactions Many reactions in the body are exchange reactions; they consist of both synthesis and decomposition reactions. One type of ex- change reaction works like this: AB ϩ CD AD ϩ BC The bonds between A and B and between C and D break (decom- position), and new bonds then form (synthesis) between A and D and between B and C. An example of an exchange reaction is HCl ϩ NaHCO3 H2CO3 ϩ NaCl Hydrochloric Sodium Carbonic Sodium acid bicarbonate acid chloride Notice that the ions in both compounds have “switched partners”: The hydrogen ion (Hϩ ) from HCl has combined with the bicarbon- ate ion (HCO3 Ϫ ) from NaHCO3, and the sodium ion (Naϩ ) from NaHCO3 has combined with the chloride ion (ClϪ ) from HCl. Reversible Reactions Some chemical reactions proceed in only one direction, from reac- tants to products, as previously indicated by the single arrows. Other chemical reactions may be reversible. In a reversible reaction, the products can revert to the original reactants. A reversible reaction is indicated by two half-arrows pointing in opposite directions: Breaks down into AB A ϩ B Combines to form Some reactions are reversible only under special conditions: Water AB A ϩ B Heat In that case, whatever is written above or below the arrows indicates the condition needed for the reaction to occur. In these reactions, AB breaks down into A and B only when water is added, and A and B react to produce AB only when heat is applied. Many reversible reactions in the body require catalysts called enzymes. Often, different enzymes guide the reactions in opposite directions. Oxidation–Reduction Reactions You will learn in Chapter 25 that chemical reactions called oxidation–reduction reactions are essential to life, since they are the reactions that break down food molecules to produce energy. These reactions are concerned with the transfer of electrons between atoms and molecules. Oxidation refers to the loss of electrons, and in the process the oxidized substance releases energy. Reduction refers to the gain of electrons, and in the process the reduced substance gains energy. Oxidation–reduction reactions are always parallel; when one substance is oxidized, another is reduced at the same time. When a food molecule, such as glucose, is oxidized, the energy produced is used by a cell to carry out its various functions. C H E C K P O I N T 7. What is the relationship between reactants and products in a chemical reaction? 8. Compare potential energy and kinetic energy. 9. How do catalysts affect activation energy? 10. How are anabolism and catabolism related to synthesis and decomposition reactions, respectively? 11. Why are oxidation–reduction reactions important? 2.3 CHEMICAL REACTIONS 39 JWCL316_c02_029-062.qxd 7/16/10 10:01 AM Page 39
  • lute solution of water (the solvent) plus small amounts of salts (the solutes). The versatility of water as a solvent for ionized or polar sub- stances is due to its polar covalent bonds and its bent shape, which allows each water molecule to interact with several neighboring ions or molecules. Solutes that are charged or contain polar cova- lent bonds are hydrophilic (hydro- ϭ water; -philic ϭ loving), which means they dissolve easily in water. Common examples of hydrophilic solutes are sugar and salt. Molecules that contain mainly nonpolar covalent bonds, by contrast, are hydrophobic (-phobic ϭ fearing). They are not very water soluble. Examples of hydrophobic compounds include animal fats and vegetable oils. To understand the dissolving power of water, consider what happens when a crystal of a salt such as sodium chloride (NaCl) is placed in water (Figure 2.10). The electronegative oxygen 40 CHAPTER 2 • THE CHEMICAL LEVEL OF ORGANIZATION 2.4 INORGANIC COMPOUNDS AND SOLUTIONS O B J E C T I V E S • Describe the properties of water and those of inorganic acids, bases, and salts. • Distinguish among solutions, colloids, and suspensions. • Define pH and explain the role of buffer systems in homeostasis. Most of the chemicals in your body exist in the form of com- pounds. Biologists and chemists divide these compounds into two principal classes: inorganic compounds and organic com- pounds. Inorganic compounds usually lack carbon a