Principles of Human Physiology 5th Edition PDF

 PRINCIPLES OF Human Physiology Fifth Edition CINDY L. STANFIELD University of South Alabama Boston Columbus Indianapolis New York San Francisco Upper Saddle River Amsterdam Cape Town Dubai London M...

 PRINCIPLES OF Human Physiology Fifth Edition CINDY L. STANFIELD University of South Alabama Boston Columbus Indianapolis New York San Francisco Upper Saddle River Amsterdam Cape Town Dubai London Madrid Milan Munich Paris Montréal Toronto Delhi Mexico City São Paulo Sydney Hong Kong Seoul Singapore Taipei Tokyo Acquisitions Editor: Kelsey Churchman Project Editor: Susan Scharf Director of Development: Barbara Yien Development Editor: Cindi Crismon Jones Art Development Editor: Jay McElroy Assistant Editor: Ashley Williams Executive Media Producer: Liz Winer Media Coordinator: Annie Wang Text Permissions Project Manager: Alison Bruckner Text Permissions Specialist: Sarah Smith, Creative Compliance Senior Managing Editor: Deborah Cogan Assistant Managing Editor: Nancy Tabor Project Management and Composition: PreMediaGlobal Production Manager: Jared Sterzer Illustration: Precision Graphics Design Supervisor: Derek Bacchus Cover and Text Designer: Tamara Newman Photo Lead: Donna Kalal Photo Researcher: Kristin Piljay Photo Permissions Management: PreMediaGlobal Marketing Manager: Derek Perrigo Senior Manufacturing Buyer: Stacey Weinberger Cover Photo Credit: Torsten Wittmann, University of California at San Francisco Credits and acknowledgments for materials borrowed from other sources and reproduced, with permission, in this textbook appear on the appropriate page within the text in the case of art or text material and on p. 727 in the case of photos. Copyright © 2013, 2012, 2011 Pearson Education, Inc. All rights reserved. Manufactured in the United States of America. This publication is protected by Copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. To obtain permission(s) to use material from this work, please submit a written request to Pearson Education, Inc., Permissions Department, 1900 E. Lake Ave., Glenview, IL 60025. For information regarding permissions, call (847) 486-2635. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trade- marks. Where those designations appear in this book, and the publisher was aware of a trademark claim, the desig- nations have been printed in initial caps or all caps. MasteringA&P®, A&P Flix™, Interactive Physiology®, and PhysioEx™ are trademarks, in the U.S. and/or other coun- tries, of Pearson Education, Inc. or its affiliates. Library of Congress Cataloging-in-Publication Data. Stanfield, Cindy L. Principles of human physiology / Cindy L. Stanfield.—5th ed. p. cm. ISBN-13: 978-0-321-81934-5 ISBN-10: 0-321-81934-9 1. Human physiology—Textbooks. I. Title. QP34.5.G465 2013 612—dc23 2012024832 ISBN 10: 0-321-81934-9; ISBN 13: 978-0-321-81934-5 (Student edition) ISBN 10: 0-321-85907-3; ISBN 13: 978-0-32185907-5 (Instructor’s Review Copy) www.pearsonhighered.com 1 2 3 4 5 6 7 8 9 10—CRK—16 15 14 13 12  In loving memory of Addie Thurston and Judy Thurston Two wonderful mothers who are loved and missed. C.L.S. About the Author Cindy L. Stanfield earned a B.S. degree and a Ph.D. in physiology at the University of California at Davis. Her exposure to neurophysiology research as an undergraduate sparked her interest in pursuing a Ph.D. As a graduate student, she studied the role of neuropeptides in pain modulation and taught several physiology laboratory courses, which led to her interest in teach- ing. She currently teaches human physiology and neuroscience lecture courses and a lecture/discussion course in issues in biomedical sciences at the University of South Alabama. She recently retired from her research responsibilities to take on the duties of advising pre-health students. Cindy currently serves as the National President of Alpha Epsilon Delta (AED), the nation- al Prehealth Honor Society. She received the College of Allied Health Professions Excellence in Service Award in 2003, and the University of South Alabama Alumni Association Excellence in Teaching Award in 2004. She is an active member of several professional organizations, includ- ing the American Physiology Society, the Human Anatomy and Physiology Society, and the National Association of Advisors for the Health Professions. She lives in Mobile, Alabama, with her husband, Jim, and their many cats and dogs. Preface The guiding philosophy for this textbook was to create a Clinical content has been expanded to encourage readers to rich resource that makes it as easy as possible for students to learn make connections throughout the book, including Health Fact the fundamentals of human physiology while also providing a solid, and Functional Fact icons that highlight content covering comprehensive, and current overview of the field. It is our belief that disease states and related aspects of body functioning. a physiology textbook should emphasize deeper understanding of New Focus on Diabetes boxes have been added throughout concepts over mere memorization of facts, in concert with useful tools the text, emphasizing this key topic more prominently for readers. for students with varying levels of preparation in biology, chemistry, Key figures for cellular and molecular art have been enhanced physics, and related sciences, to aid them in their individual studies. with more saturated colors and added dimensionality. In developing the fifth edition, we’ve made several ambitious A new interior design updates and enlivens the text, enhancements with these goals in mind, while retaining the book’s focuses on the clinical features, and helps students better proven and trusted hallmarks: a direct and precise writing style; a navigate the text by making the content organization clearer clear and illuminating art program designed to maximize student and easier to use. learning; and pedagogical features that stimulate users’ interest, Learning Outcomes are more prominent and are emphasized help readers think about physiological processes in an integrated at the start of each chapter. way, and reinforce the most important concepts. Chapter Outlines are now numbered, helping students better The most wide-ranging advancement in the fifth edition is the understand each chapter’s organization, connecting to the main addition of MasteringA&P®, the most effective and widely used online headings across each chapter and again in the summary. tutorial, homework, and assessment platform and system for the scienc- The Chapter Summary is presented in a briefer, bulleted es. This online tool utilizes the most current resources, including chapter format correlated to the Chapter Outline. Extended chapter quizzes, self-paced tutorials, practice tests, guided animations, interac- summaries can be found in the MasteringA&P® Study Area. tive physiological processes, and expansive laboratory simulations. Quick Test sections have reviewed, revised and expanded In this edition we have also both expanded and focused our as needed, and the feature name has been changed previous diabetes emphasis by illustrating on a text-wide basis the to Quick Check. concept of diabetes as a touchstone disease—one that affects all The Immune System content (Chapter 23) has undergone body systems and provides a comprehensive example of how the an extensive, expert review and is updated with the most body responds to disease and attempts to restore homeostasis. This current and accurate information, including new figures, content has been expanded to touch every applicable chapter in the expanded coverage of HIV and AIDs-related content, and Major text, and has been focused through the introduction of new Focus Histocompatability Complex (MHC) markers on Diabetes boxes, which highlight the material for easier reference. End-of-Chapter Systems Integration sections have been expanded to now include every chapter in the text, relating chapter content to what has already been learned, and New to the Fifth Edition preparing students for what will be presented. In response to the feedback we received from users, reviewers, and End-of-Chapter Exercises are now numbered sequentially instructors, we have made the following key enhancements to this though the whole section, for easier navigation. edition. For more details on these enhancements and the text’s other features, MasteringA&P®, an integrated text and technology learning please see the visual overview at the front of this text. In addition, system focusing on student comprehension and instructor each chapter has been thoroughly revised in response to reviewer adaptability, with reinforced clinical content, is now included suggestions, and to reflect current research, capture a more readable in this edition. Assignable, text-specific assets include online style, and for greatest clarity and precision. The following is a sum- homework, tutorial, and assessment systems; self-paced mary of some of the specific changes to each chapter. tutorials; and customizable, assignable, and automatically graded assessments. MasteringA&P® icons and references appear at appropriate places throughout each chapter to direct Chapter 1 Introduction to Physiology students to related online resources. Revised and expanded Learning Outcomes New Critical Thinking Questions appear within each Added questions to Quick Checks 1.1 and 1.2 Clinical Connections box to encourage further thinking and Enhanced Figures 1.4 and 1.5 associations, and tie-in to Mastering activities. Added new Focus on Diabetes box iv  Preface v Chapter 2 The Cell: Structure and Chapter 9 The Nervous System: Central Function Nervous System Expanded and revised carbohydrates content; added new Added the Clinical Connections box “Glial Cells in headers “Monosaccharides, Disaccharides, and Polysaccharides” Neurodegenerative Diseases” and “Synthesis and Breakdown of Saccharides” Revised headers and discussion in sections 9.4 and 9.5 regarding Enhanced Figures 2.4, 2.5, 2.15, 2.16, 2.20, 2.24, 2.25, and 2.35 voluntary and involuntary movements Revised Apply Your Knowledge, page 23 Chapter 10 The Nervous System: Added two new Focus on Diabetes boxes, one with new Figure 2.3 Added new Clinical Connections box on Tay-Sachs disease Sensory Systems Removed prior Figure 2.41 Added new Focus on Diabetes box Chapter 3 Cell Metabolism Enhanced Figure 10.32 Added new sub-headers “Bipolar Cell Receptive Fields” Added new header 3.4 on ATP, and expanded discussion and “Ganglion Cell Receptive Fields” and expanded Added header “Chemical Equilibrium” and expanded discussion discussion Added two new Focus on Diabetes boxes Added new table 3.1 Chapter 11 The Nervous System: Added headers “The Linking Step” and “Reactions of the Krebs Autonomic and Motor Systems Cycle” in the Krebs cycle content, and revised content Enhanced Figure 11.8 Enhanced Figure 3.20 Added new Table 11.2, “Drugs Affecting the Autonomic Added header “Glucose Catabolism in the Absence of Oxygen” Nervous System” and revised content Added new Focus on Diabetes box Revised Figures 3.26, 3.27, and 3.28 Chapter 12 Muscle Physiology Chapter 4 Cell Membrane Transport Revised, expanded, and reorganized content on the mechanics of Enhanced Figures 4.10, 4.12, 4.14, 4.21, and 4.22 skeletal muscle contraction, and muscle cell metabolism Added two new Focus on Diabetes boxes Added section 12.4 on Skeletal Muscle Metabolism Revised Toolbox content on “Determining the Osmotic Pressure Added new Figure 12.23 of a Solution” Added new Quick Check 12.4 Chapter 5 Chemical Messengers Added new Focus on Diabetes box Enhanced Figures 5.1, 5.3, 5.13, 5.14, 5.15, 5.17, and 5.18 Chapter 13 The Cardiovascular System: Added new Focus on Diabetes box Cardiac Function Added new Figure 5.12 Revised “Before You Begin” starting points Revised Exercises questions Added new Focus on Diabetes box Chapter 6 The Endocrine System: Enhanced Figures 13.25 and 13.26 Endocrine Glands and Hormone Actions Chapter 14 The Cardiovascular System: Enhanced Figures 6.9 and 6.10 Blood Vessels, Blood Flow, and Blood Added new Focus on Diabetes box Pressure Removed an Apply Your Knowledge section to reflect revised text Added header and new content on “Discontinuous Capillaries Chapter 7 Nerve Cells and Electrical and Sinusoids” Signaling Revised Figure 14.28 Added new Figures 7.3 and 7.4 Dropped prior Toolbox on Compliance to reflect content revisions Enhanced Figures 7.7 and 7.17 Added two new sub-headers under “Graded Potentials” and Chapter 15 The Cardiovascular System: expanded discussion Added new header “The All-or-None Principle of Action Blood Potentials” and expanded discussion Revised Table 15.1, “Components of Plasma” Added new Focus on Diabetes box Added new Figure 15.6 Chapter 8 Synaptic Transmission and Added new Focus on Diabetes box Neural Integration Revised Learning Outcomes to reflect updated content Enhanced Figures 8.3, 8.4, 8.5, and 8.11 vi Preface Chapter 16 The Respiratory System: Chapter 22 The Reproductive System Pulmonary Ventilation Added new Figures 22.1 and 22.2 Added new graphic for Clinical Connections box on Sleep Apnea Added new Clinical Connections box on X-Linked Genes Revised Figure 16.4 Revised Figures 22.7, 22.15, and 22.20 Enhanced Figure 16.15 Added a new header and section on Fetal Development Added new Figures 16.17 and 16.18 on pulmonary function tests Added new Focus on Diabetes box and related data Added Systems Integration section Chapter 17 The Respiratory System: Gas Chapter 23 The Immune System Exchange and Regulation of Breathing Added header and section 23.2 on “Pathogens that Activate the Immune Response” Revised Learning Outcomes Revised and expanded the Learning Outcomes Revised Figure 17.15 Expanded “Before You Begin” starting points Chapter 18 The Urinary System: Renal Revised and reorganized content on physical barriers to now fall in section 23.1 Function Added new Figures 23.1, 23.2, 23.4, 23.7, 23.8, 23.10, 23.15, and Expanded Clinical Connections box on Dialysis to include more 23.18 content on end-stage renal disease Expanded discussion on central and peripheral lymphoid tissues Added Clinical Connections box on Urinary Incontinence Expanded pathogens content to include discussion of viruses, bacteria, fungi, and parasites Chapter 19 The Urinary System: Fluid and Electrolyte Balance Expanded discussion of pathways within the complement system Expanded “Before You Begin” starting points Converted prior Table 23.1 into a figure Added Clinical Connections box on Water Intoxication Added new Table 23.2, “Recommended Vaccinations” Added new Figures 19.8 and 19.9 Added new Clinical Connections box on AIDs Added new Focus on Diabetes box Added Systems Integration section Chapter 20 The Gastrointestinal System Chapter 24 Diabetes Mellitus Expanded “Before You Begin” starting points Added header and expanded content on acute hyperglycemia in Added new Figure 20.4 section 24.2 Enhanced the graphic in Discovery box “Lipoproteins and Added new Figures 24.2, 24.3, 24.4, 24.6 Plasma Cholesterol” Added header and expanded discussion of “Development of New Added new Focus on Diabetes box Medications for Treatment” Added new Figure 20.23 Chapter 21 The Endocrine System: Regulation of Energy Metabolism and Growth Expanded “Before You Begin” starting points Added new Figure 21.6 Added new Focus on Diabetes box Acknowledgments As I complete the fifth edition of the textbook, my relation- In addition, I would like to express my thanks to the numerous ship with all of the supporting personnel has grown. Although the reviewers and contributors who provided feedback on the prior revision process is a heavy undertaking, the team at Pearson Higher edition and suggestions for this revision. Instructor comments are Education has continued to make the experience not just manage- valued and seriously considered during each revision cycle. Please able, but actually enjoyable. Throughout the revision I benefited continue to send them! Special thanks to William (Brad) Davis, my from the expertise and hard work of many editors, reviewers, design- colleague at the University of South Alabama, for his expert assis- ers, production and marketing staff, and instructors. I extend to tance with the Immune System chapter revision, and to Heather them my deepest and heartfelt thanks. Wilson-Ashworth, of Utah Valley University, for her assistance in To begin, I want to acknowledge Frank Ruggirello, Serina developing the Clinical Connections boxes’ new Critical Thinking Beauparlant, Barbara Yien, and Kelsey Churchman for their leader- Questions. ship and investment in this text. Thanks to my Project Editor, Susan There are no words that can express the gratitude I have for the Scharf, for her guidance and support during the work on this edi- support and encouragement of my wonderful husband Jim. Without tion. I also want to extend my sincere thanks to Jay McElroy, Art him, there would be no text. I am also grateful to several friends and Development Manager, for his great work on the art program, which colleagues at the University of South Alabama, who supported my has improved the overall text. My gratitude also goes to my develop- endeavors. Thanks to Sally Bru, Terry Ravine, and Robin Mockett mental editor for this edition, Cindi Crismon Jones, for her insightful for comments on the text. A special thanks goes to W. Brad Davis for suggestions on refining the text. Cindi was a true delight to work with. helping with the major revision of the immunology chapter. Thanks Thanks to everyone involved in the book’s production and to Gina Deckard and Jaime Lett for technical assistance. I also thank design development, particularly Nancy Tabor, Jared Sterzer, my family for their love and support: John, Janice, Mike, Pat, Jim, Joe, Deborah Cogan, Marilyn Perry, Derek Bacchus, Donna Kalal, and and Steve; and all my nieces, nephews, grandnieces and grandnephews. Tamara Newman. Thanks also to Ashley Williams and Robin Pille And Jenny, thank you for being strong when your mother and my for expertly coordinating the print supplements for this edition. In brother needed it most. addition, I would like to thank Liz Winer and Annie Wang for their work on the media and Mastering assets. Thanks as well to the Pearson marketing staff, Derek Perrigo, Lauren Harp, Christy Lesko, Jane Campbell, and Jessica Perry, for their dedication and creativity. Cindy L. Stanfield vii viii Acknowledgments Fifth Edition Reviewers Our thanks to the following reviewers for their insightful and important contributions to the development of this edition: Ricardo Araneda Daniel Fogell Richard Mynark University of Maryland, College Park Southeast Community College Indiana University Tyson Chappell Marie Kelly-Worden David Petzel Utah State University, College of Eastern Ball State University Creighton University Utah Dean Lauritzen Deborah Taylor William Davis City College of San Francisco Kansas City Kansas Community College University of South Alabama Reza Majlesi Josh Titlow Diego DeLeon College of Alameda University of Kentucky (previously at University of Miami Charles Marshall Marshall University) Jennifer Doyle University of Kentucky Spalding University Brief Contents 1 Introduction to Physiology 1 15 The Cardiovascular System: Blood 432 2 The Cell Structure and Function 18 16 The Respiratory System: Pulmonary Ventilation 448 3 Cell Metabolism 56 17 The Respiratory System: 4 Cell Membrane Transport 93 Gas Exchange and Regulation of Breathing 473 5 Chemical Messengers 124 18 The Urinary System: 6 The Endocrine System: Endocrine Glands Renal Function 503 and Hormone Actions 148 19 The Urinary System: Fluid and Electrolyte Balance 531 7 Nerve Cells and Electrical Signaling 166 20 The Gastrointestinal System 565 8 Synaptic Transmission and Neural Integration 196 21 The Endocrine System: Regulation of Energy Metabolism and Growth 602 9 The Nervous System: Central Nervous System 215 22 The Reproductive System 631 10 The Nervous System: Sensory Systems 253 23 The Immune System 668 24 Diabetes Mellitus 701 11 The Nervous System: Autonomic and Motor Systems 303 Answers to Figure Questions, Apply Your Knowledge, and End-of-Chapter Multiple Choice and Objective Questions 720 12 Muscle Physiology 322 Credits 727 13 The Cardiovascular System: Cardiac Function 359 Glossary 729 Index 748 14 The Cardiovascular System: Blood, Blood Flow, and Blood Pressure 394 ix Contents 1 Introduction to Physiology 1 Cell Division 50 Replication of DNA The Cell Cycle Organization of the Body 2 Chapter Summary 53 Cells, Tissues, Organs, and Organ Systems The Overall Body Plan: A Simplified View Exercises 54 Homeostasis: A Central Organizing Principle of Physiology 9 3 Cell Metabolism 56 Negative Feedback Control in Homeostasis Types of Metabolic Reactions 57 The Diabetes Epidemic 13 Hydrolysis and Condensation Reactions Phosphorylation and Dephosphorylation Reactions Oxidation-Reduction Prevalence of Diabetes Obesity and Diabetes Reactions Classification of Diabetes Diagnosing Diabetes Mellitus Symptoms of Diabetes Mellitus Treatment of Diabetes Metabolic Reactions and Energy 59 Mellitus Energy and the Laws of Thermodynamics Energy Changes Chapter Summary 16 in Reactions Activation Energy Exercises 17 Reaction Rates 63 Factors Affecting the Rates of Chemical Reactions The 2 The Cell Structure and Role of Enzymes in Chemical Reactions Function 18 ATP: The Medium of Energy Biomolecules 19 Exchange 72 Carbohydrates Monosaccharides, Disaccharides, and Glucose Oxidation: The Central Reaction Polysaccharides Lipids Amino Acids and Proteins of Energy Metabolism 73 Nucleotides and Nucleic Acids Coupling Glucose Oxidation to ATP Synthesis Cell Structure 29 Stages of Glucose Oxidation: Glycolysis, Structure of the Plasma Membrane Structure of the Krebs Cycle, and Oxidative the Nucleus Contents of the Cytosol Structure of Phosphorylation 74 Membranous Organelles Structure of Nonmembranous Organelles Glycolysis The Krebs Cycle Oxidative Phosphorylation The Electron Transport Chain Summary of Glucose Cell-to-Cell Adhesions 39 Oxidation Glucose Catabolism in the Absence Tight Junctions Desmosomes Gap Junctions of Oxygen General Cell Functions 40 Energy Storage and Use: Metabolism Metabolism Cellular Transport Intercellular of Carbohydrates, Fats, and Communication Proteins 84 Glycogen Metabolism Gluconeogenesis: Formation Protein Synthesis 42 of New Glucose Fat Metabolism Protein The Role of the Genetic Code Transcription Destination Metabolism of Proteins Post-translational Processing and Packaging of Proteins Regulation of Protein Synthesis Protein Chapter Summary 90 Degradation Exercises 91 x  Contents xi 4 Cell Membrane Transport 93 6 The Endocrine System: Factors Affecting the Direction of Endocrine Glands and Hormone Transport 94 Actions 148 Passive Transport Versus Active Transport Driving Forces Primary Endocrine Organs 149 Acting on Molecules Hypothalamus and Pituitary Gland Pineal Gland Rate of Transport 100 Thyroid Gland and Parathyroid Glands Thymus Adrenal Glands Pancreas Gonads Passive Transport 101 Secondary Endocrine Organs 156 Simple Diffusion: Passive Transport Through the Lipid Bilayer Facilitated Diffusion: Passive Transport Utilizing Hormone Actions at the Target Cell 158 Membrane Proteins Diffusion Through Channels Control of Hormone Levels in Blood Active Transport 106 Abnormal Secretion of Hormones 161 Primary Active Transport Secondary Active Transport Factors Affecting Rates of Active Transport Coexistence Hormone Interactions 162 of Active and Passive Transport Mechanisms in Cells Chapter Summary 164 Osmosis: Passive Transport of Water Exercises 164 Across Membranes 110 Osmolarity Osmotic Pressure Tonicity 7 Nerve Cells and Electrical Transport of Material Within Membrane- Signaling 166 Bound Compartments 114 Overview of the Nervous System 167 Transport of Molecules into Cells by Endocytosis Cells of the Nervous System 168 Transport of Molecules Out of Cells by Exocytosis Neurons Glial Cells Epithelial Transport: Movement of Establishment of the Resting Membrane Molecules Across Two Membranes 117 Potential 174 Epithelial Structure Epithelial Solute Transport Epithelial Determining the Equilibrium Potentials for Potassium and Water Transport Transcytosis Sodium Ions Resting Membrane Potential of Neurons Chapter Summary 121 Neurons at Rest Exercises 122 Electrical Signaling Through Changes in Membrane Potential 179 5 Chemical Messengers 124 Describing Changes in Membrane Potential Graded Mechanisms of Intercellular Potentials Action Potentials Propagation of Action Communication 125 Potentials Direct Communication Through Gap Junctions Indirect Maintaining Neural Stability 193 Communication Through Chemical Messengers Chapter Summary 193 Chemical Messengers 126 Exercises 194 Functional Classification of Chemical Messengers Chemical Classification of Messengers Synthesis and Release of Chemical Messengers Transport of Messengers 8 Synaptic Transmission and Neural Integration 196 Signal Transduction Mechanisms 134 Electrical Synapses 197 Properties of Receptors Signal Transduction Mechanisms for Responses Mediated by Intracellular Receptors Signal Chemical Synapses 197 Transduction Mechanisms for Responses Mediated by Functional Anatomy of Chemical Synapses Signal Membrane-Bound Receptors Transduction Mechanisms at Chemical Synapses Excitatory Synapses Inhibitory Synapses Long-Distance Communication via the Nervous and Endocrine Systems 144 Neural Integration 203 Chapter Summary 145 Summation Frequency Coding Exercises 146 xii Contents Presynaptic Modulation 205 10 The Nervous System: Sensory Presynaptic Facilitation Presynaptic Inhibition Systems 253 Neurotransmitters: Structure, Synthesis, General Principles of Sensory and Degradation 207 Physiology 254 Acetylcholine Biogenic Amines Amino Acid Receptor Physiology Sensory Pathways Sensory Coding Neurotransmitters Purines Neuropeptides Unique Neurotransmitters The Somatosensory System 262 Somatosensory Receptors The Somatosensory Cortex Chapter Summary 212 Somatosensory Pathways Pain Perception Exercises 213 Vision 269 9 The Nervous System: Central Anatomy of the Eye The Nature and Behavior of Light Waves Accommodation Clinical Defects in Vision Nervous System 215 Regulating the Amount of Light Entering the Eye General Anatomy of the Central Nervous The Retina Phototransduction Rods versus Cones System 216 Color Vision Light Input to Circadian Rhythms Bleaching of Photoreceptors in Light Neural Processing Glial Cells Physical Support of the Central Nervous System in the Retina Neural Pathways for Vision Parallel Blood Supply to the Central Nervous System The Blood- Processing in the Visual System Depth Perception Brain Barrier Gray Matter and White Matter The Spinal Cord 224 The Ear and Hearing 285 Anatomy of the Ear The Nature of Sound Waves Sound Spinal Nerves Spinal Cord Gray and White Matter Amplification in the Middle Ear Signal Transduction for The Brain 229 Sound Neural Pathways for Sound Cerebral Cortex Subcortical Nuclei Diencephalon The Ear and Equilibrium 292 Limbic System Anatomy of the Vestibular Apparatus The Semicircular Integrated CNS Function: Involuntary Canals and the Transduction of Rotation The Utricle and Movement Through Reflexes 236 Saccule and the Transduction of Linear Acceleration Stretch Reflex Withdrawal and Crossed-Extensor Reflexes Neural Pathways for Equilibrium Integrated CNS Function: Voluntary Taste 295 Motor Control 238 Anatomy of Taste Buds Signal Transduction in Taste Neural Components for Smooth Voluntary Movements Neural Pathway for Taste Lateral Pathways Control Voluntary Movement Olfaction 297 Ventromedial Pathways Control Voluntary and Anatomy of the Olfactory System Olfactory Signal Involuntary Movements The Control of Posture by Transduction Neural Pathway for Olfaction the Brainstem The Role of the Cerebellum in Motor Coordination The Basal Nuclei in Motor Control Chapter Summary 299 Exercises 301 Integrated CNS Function: Language 242 Integrated CNS Function: Sleep 242 Functions of Sleep Sleep-Wake Cycles Electrical Activity 11 The Nervous System: Autonomic and Motor During Wakefulness and Sleep Systems 303 Integrated CNS Function: Emotions and The Autonomic Nervous System 304 Motivation 245 Dual Innervation in the Autonomic Nervous System Integrated CNS Function: Learning and Anatomy of the Autonomic Nervous System Memory 247 Autonomic Neurotransmitters and Receptors Autonomic Learning Memory Plasticity in the Nervous System Neuroeffector Junctions Regulation of Autonomic Function Chapter Summary 250 The Somatic Nervous System 315 Exercises 251 Anatomy of the Somatic Nervous System The Neuromuscular Junction Chapter Summary 320 Exercises 321  Contents xiii 12 Muscle Physiology 322 Cardiac Output and Its Control 382 Autonomic Input to the Heart Factors Affecting Cardiac Skeletal Muscle Structure 323 Output: Changes in Heart Rate Factors Affecting Cardiac Structure at the Cellular Level Structure at the Output: Changes in Stroke Volume Integration of Factors Molecular Level Affecting Cardiac Output The Mechanism of Force Generation Chapter Summary 390 in Muscle 326 Exercises 392 The Sliding-Filament Model The Crossbridge Cycle: How Muscles Generate Force Excitation-Contraction Coupling: 14 The Cardiovascular System: How Muscle Contractions Are Turned On and Off Blood Vessels, Blood Flow, and The Mechanics of Skeletal Muscle Blood Pressure 394 Contraction 331 Physical Laws Governing Blood Flow The Twitch Factors Affecting the Force Generated and Blood Pressure 395 by Individual Muscle Fibers Regulation of the Force Pressure Gradients in the Cardiovascular System Generated by Whole Muscles Velocity of Shortening Resistance in the Cardiovascular System Relating Skeletal Muscle Metabolism 340 Pressure Gradients and Resistance in the Systemic Muscle Cell Metabolism: How Muscle Cells Generate ATP Circulation Types of Skeletal Muscle Fibers Overview of the Vasculature 398 Control of Skeletal Muscle Activity 347 Arteries 399 Muscle Activity Across Joints Muscle Receptors for Arteries: A Pressure Reservoir Arterial Blood Pressure Coordinated Activity Arterioles 402 Smooth and Cardiac Muscle 350 Arterioles and Resistance to Blood Flow Intrinsic Control Smooth Muscle Cardiac Muscle of Blood Flow Distribution to Organs Extrinsic Control of Chapter Summary 355 Arteriole Radius and Mean Arterial Pressure Exercises 356 Capillaries and Venules 409 Capillary Anatomy Local Control of Blood Flow Through 13 The Cardiovascular System: Capillary Beds Movement of Material Across Capillary Cardiac Function 359 Walls Venules An Overview of the Cardiovascular Veins 416 System 360 Veins: A Volume Reservoir Factors That Influence Venous The Heart Blood Vessels Blood Pressure and Venous Return The Path of Blood Flow Through the The Lymphatic System 419 Heart and Vasculature 362 Mean Arterial Pressure and Its Series Flow Through the Cardiovascular System Parallel Regulation 419 Flow Within the Systemic or Pulmonary Circuit Determinants of Mean Arterial Pressure: Heart Rate, Anatomy of the Heart 365 Stroke Volume, and Total Peripheral Resistance Regulation of Mean Arterial Pressure Control of Blood Myocardium and the Heart Wall Valves and Unidirectional Pressure by Low-Pressure Baroreceptors Blood Flow (Volume Receptors) Electrical Activity of the Heart 367 Other Cardiovascular Regulatory The Conduction System of the Heart Pacemaker Cells of Processes 426 the Myocardium Spread of Excitation Through the Heart Muscle The Ionic Basis of Electrical Activity in the Heart Respiratory Sinus Arrhythmia Chemoreceptor Reflexes Recording the Electrical Activity of the Heart with an Thermoregulatory Responses Electrocardiogram Chapter Summary 429 The Cardiac Cycle 377 Exercises 430 Phases of the Cardiac Cycle Atrial and Ventricular Pressure Aortic Pressure Ventricular Volume Pressure-Volume Curve Heart Sounds xiv Contents 15 The Cardiovascular System: Exchange of Oxygen and Carbon Dioxide 478 Blood 432 Gas Exchange in the Lungs Gas Exchange in Respiring Overview of the Composition of Blood: Tissue Determinants of Alveolar Po2 and Pco2 The Hematocrit 433 Transport of Gases in the Blood 481 Plasma 434 Oxygen Transport in the Blood Carbon Dioxide Transport Erythrocytes 434 in the Blood Oxygen and Carbon Dioxide Transport Life Cycle of Central Regulation of Ventilation 489 Erythrocytes Neural Control of Breathing by Motor Neurons Generation Leukocytes 438 of the Breathing Rhythm in the Brainstem Peripheral Input to Respiratory Centers Neutrophils Eosinophils Basophils Monocytes Lymphocytes Control of Ventilation by Platelets and Hemostasis 441 Chemoreceptors 492 Vascular Spasm Platelet Plug Formation of a Blood Clot Chemoreceptors Chemoreceptor Reflexes Diabetes and Cardiovascular Local Regulation of Ventilation and Disease 445 Perfusion 495 Ventilation-Perfusion Ratios Local Control of Ventilation Chapter Summary 446 and Perfusion Exercises 447 The Respiratory System in Acid-Base Homeostasis 496 16 The Respiratory System: Acid-Base Disturbances in Blood The Role of the Pulmonary Ventilation 448 Respiratory System in Acid-Base Balance Overview of Respiratory Function 449 Chapter Summary 500 Anatomy of the Respiratory Exercises 501 System 449 Upper Airways The Respiratory Tract Structures of the 18 The Urinary System: Renal Thoracic Cavity Function 503 Forces for Pulmonary Ventilation 457 Functions of the Urinary System 504 Pulmonary Pressures Mechanics of Breathing Anatomy of the Urinary System 505 Factors Affecting Pulmonary Structures of the Urinary System Macroscopic Anatomy of Ventilation 461 the Kidney Microscopic Anatomy of the Kidney Lung Compliance Airway Resistance Blood Supply to the Kidney Clinical Significance of Respiratory Basic Renal Exchange Processes 508 Volumes and Air Flows 465 Glomerular Filtration Reabsorption Lung Volumes and Capacities Pulmonary Function Tests Transport Maximum Secretion Alveolar Ventilation Regional Specialization of the Renal Chapter Summary 470 Tubules 519 Exercises 471 Nonregulated Reabsorption in the Proximal Tubule Regulated Reabsorption and Secretion in the Distal 17 The Respiratory System: Gas Tubule and Collecting Duct Water Conservation in the Loop of Henle Exchange and Regulation of Breathing 473 Excretion 520 Excretion Rate Clearance Micturition Overview of the Pulmonary Circulation 474 Chapter Summary 527 Exercises 529 Diffusion of Gases 476 Partial Pressure of Gases Solubility of Gases in Liquids  Contents xv 19 The Urinary System: Fluid and Gastrointestinal Secretion and Its Regulation 590 Electrolyte Balance 531 Saliva Secretion Acid and Pepsinogen Secretion in the The Concept of Balance 532 Stomach Secretion of Pancreatic Juice and Bile Rates of Factors Affecting the Plasma Composition Solute and Fluid Movement in the Digestive System Water Balance Gastrointestinal Motility and Its Water Balance 534 Regulation 594 Osmolarity and the Movement of Water Water Electrical Activity in Gastrointestinal Smooth Muscle Reabsorption in the Proximal Tubule Establishment of Peristalsis and Segmentation Chewing and Swallowing the Medullary Osmotic Gradient Role of the Medullary Gastric Motility Motility of the Small Intestine Motility Osmotic Gradient in Water Reabsorption in the Distal of the Colon Tubule and Collecting Duct Chapter Summary 599 Sodium Balance 543 Exercises 600 Mechanisms of Sodium Reabsorption in the Renal Tubule The Effects of Aldosterone Atrial Natriuretic Peptide 21 The Endocrine System: Regulation of Energy Potassium Balance 548 Metabolism and Growth 602 Renal Handling of Potassium Ions Regulation of Potassium Secretion by Aldosterone An Overview of Whole-Body Metabolism 603 Calcium Balance 549 Anabolism Regulation of Metabolic Pathways Renal Handling of Calcium Ions Hormonal Control of Plasma Calcium Concentrations Energy Intake, Utilization, and Storage 604 Interactions Between Fluid and Uptake, Utilization, and Storage of Energy in Carbohydrates Electrolyte Regulation 551 Uptake, Utilization, and Storage of Energy in Proteins Acid-Base Balance 553 Uptake, Utilization, and Storage of Energy in Fats Sources of Acid-Base Disturbances Defense Mechanisms Energy Balance 605 Against Acid-Base Disturbances Compensation for Acid- Energy Input Energy Output Metabolic Rate Base Disturbances Negative and Positive Energy Balance Chapter Summary 561 Energy Metabolism During the Exercises 562 Absorptive and Postabsorptive States 607 20 The Gastrointestinal Metabolism During the Absorptive State Metabolism System 565 During the Postabsorptive State Overview of Gastrointestinal System Regulation of Absorptive and Processes 566 Postabsorptive Metabolism 611 Functional Anatomy of the The Role of Insulin The Role of Glucagon Negative Feedback Control of Blood Glucose Levels by Insulin Gastrointestinal System 566 and Glucagon Effects of Epinephrine and Sympathetic The Gastrointestinal Tract The Accessory Glands Nervous Activity on Metabolism Digestion and Absorption of Nutrients Thermoregulation 616 and Water 578 Temperature Balance Mechanisms of Heat Transfer Carbohydrates Proteins Lipids Absorption of Vitamins between the Body and the External Environment Absorption of Minerals Absorption of Water Regulation of Body Temperature Alterations in the General Principles of Gastrointestinal Set Point for Thermoregulation: Fever Regulation 587 Hormonal Regulation of Growth 619 Neural and Endocrine Pathways of Gastrointestinal Control Body Growth Effects of Growth Hormone Other Regulation of Food Intake Hormones That Affect Growth xvi Contents Thyroid Hormones 624 Cell-Mediated Immunity 687 Synthesis and Secretion of Thyroid Hormones Actions of Roles of T Lymphocytes in Cell-Mediated Immunity Thyroid Hormones Helper T Cell Activation Cytotoxic T Cell Activation: The Destruction of Virus-Infected Cells and Tumor Cells Glucocorticoids 626 Factors Affecting Secretion of Glucocorticoids Actions Immune Responses in Health and of Glucocorticoids The Role of Cortisol in the Stress Disease 690 Response Effects of Abnormal Glucocorticoid Secretion Generating Immunity: Immunization Roles of the Chapter Summary 628 Immune System in Transfusion and Transplantation Immune Dysfunctions Exercises 629 Chapter Summary 698 22 The Reproductive System 631 Exercises 699 An Overview of Reproductive Physiology 632 24 Diabetes Mellitus 701 The Role of Gametes in Sexual Reproduction Gene Sorting Classification of Diabetes Mellitus 702 and Packaging in Gametogenesis: Meiosis Components of Type 1 Diabetes Mellitus Type 2 Diabetes Mellitus the Reproductive System Events Following Fertilization Patterns of Reproductive Activity over the Human Life Span Acute Effects of Diabetes Mellitus 704 The Male Reproductive System 638 Acute Hyperglycemia Diabetic Ketoacidosis Hyperosmolar Nonketotic Coma Hypoglycemic Coma Functional Anatomy of the Male Reproductive Organs Hormonal Regulation of Reproductive Function in Males Chronic Complications of Diabetes Sperm and Their Development The Sexual Response Mellitus: Early Stages 705 in Males Chronic Complications of Diabetes The Female Reproductive System 645 Mellitus: Advanced Stages 706 Functional Anatomy of the Female Reproductive Organs Adverse Effects of Hyperglycemia Effects of Diabetes Ova and Their Development The Sexual Response in Mellitus on the Microvasculature Females The Menstrual Cycle Long-Term Hormonal Regulation of Female Reproductive Function Progression of Diabetes Mellitus to Fertilization, Implantation, and Critical States 711 Pregnancy 655 Effects of Diabetes on the Macrovasculature Diabetic Cardiomyopathy Events of Fertilization Early Embryonic Development and Implantation Later Embryonic and Fetal Development Delayed Wound Healing 712 Hormonal Changes During Pregnancy Wound Healing Altered Wound Healing in Diabetes Parturition and Lactation 661 Treatment and Management of Diabetes Events of Parturition Lactation Mellitus 714 Chapter Summary 665 Current Research on Diabetes Exercises 666 Mellitus 715 New Techniques for Insulin Administration Development 23 The Immune System 668 of New Medicines for the Treatment of Diabetes Mellitus Nonpharmaceutical Therapies for the Treatment of Anatomy of the Immune System 669 Diabetes Mellitus Physical Barriers Leukocytes Lymphoid Tissues Chapter Summary 718 Pathogens That Activate the Immune Exercises 719 Response 673 Viruses Bacteria Fungi Parasites Answers to Figure Questions, Apply Your Knowledge, and End-of-Chapter Multiple Organization of the Body’s Defenses 675 Choice and Objective Questions 720 Nonspecific Defenses Specific Defenses: Immune Responses Credits 727 Humoral Immunity 685 Glossary 729 The Role of B Lymphocytes in Antibody Production Antibody Function in Humoral Immunity Index 748 List of Boxes Chemistry Review Clinical Connections Atoms and Molecules 22 Heat Exhaustion and Heat Stroke 10 Polar Molecules and Hydrogen Bonds 31 Tay-Sachs Disease 36 Ions and Ionic Bonds 33 Mitochondrial DNA in Disease, Anthropology, and Forensics 43 Solutions and Concentrations 61 How Ricin Kills 50 Acids, Bases, and pH 70 Cancer 52 Buffers 556 Antioxidants and the Problem with Free Radicals 82 From Aspirin to COX-2 Inhibitors 133 Cholera and G Proteins 140 Toolbox Pituitary Adenomas 163 Neurotoxins 180 Ligand-Protein Interactions 67 Local Anesthetics 192 Energy of Solutions 95 Treating Depression 210 Equilibrium Potentials and the Nernst Equation 99 The Role of GABAergic Agents in Anxiety Fick’s Law and Permeability 103 and Sleep Disorders 211 Determining the Osmotic Pressure of a Solution 113 Glial Cells in Neurodegenerative Diseases 217 Electrical Circuits in Biology 175 Stroke 221 Resting Membrane Potential and the GHK Equation 178 Post-Traumatic Stress Disorder 245 Length Constant for Electrotonic Conduction 190 Synesthesia 260 Decibels 287 Phantom Limb Pain 270 Physics of Skeletal Muscle Contraction 332 Color Blindness 284 Compliance 381 Myasthenia Gravis 318 Laplace’s Law 389 Tetanus 337 Poiseuille’s Law 398 Muscular Dystrophy 347 Boyle’s Law and the Ideal Gas Law 459 Myocardial Ischemia 364 Pulmonary Surfactant and Laplace’s Law 463 Heart Failure 415 Partial Pressures and Dalton’s Law 476 Hypertension 425 Henry’s Law and Solubility of Gases 477 Anemia 439 The Henderson-Hasselbalch Equation 498 Sleep Apnea 453 Chronic Obstructive Pulmonary Disease 465 The Bends 479 Pulmonary Edema 482 Discovery Kidney Stones 506 Vaults and Chemotherapy 36 End-Stage Renal Disease and Dialysis 519 Can Uncouplers Aid in Weight Loss? 81 Urinary Incontinence 526 Antihistamines 127 Water Intoxication 536 Circadian Rhythms and Jet Lag 160 Osteoporosis 551 Neurogenesis 170 Ulcers 572 The Story of Phineas Gage 234 Lactose Intolerance 582 Curare 319 Diverticular Disease 598 Creatine Supplements 342 X-Linked Genes 635 Leeches and Bloodletting 445 Erectile Dysfunction 645 The Effects of High Altitude 499 Ovarian Cysts 651 Don’t Drink the (Sea) Water 542 Shingles 684 Aids 693 Lipoproteins and Plasma Cholesterol 586 Multiple Sclerosis 696 Birth Control Methods 656 Gene Therapy for Severe Combined Immunodeficiency Disease 697 Bariatric Surgery as a Treatment for Diabetes 717 xvii xviii List of Boxes Understanding Exercise Focus on Diabetes Challenging Homeostasis 9 Focus on Diabetes 13 Sources of Energy for Muscle Cells 85 Ketone Bodies 22 Sweat Production 115 Focus on Diabetes 49 Chemical Messengers of Exercise 129 The Law of Mass Action 62 Why Athletes Take Steroids 157 Effects of Insulin on Cell Metabolism 89 Can Exercise Affect the Brain? 249 Glucose Transporter 4 106 Adaptations of the Peripheral Nervous System 314 Focus on Diabetes 114 Sympathetic Activity 387 Focus on Diabetes 136 Independent Regulation of Blood Flow 406 Focus on Diabetes 162 Cardiovascular Responses to Light Exercise 428 Peripheral Neuropathy 192 Effects of High Altitude 436 Focus on Diabetes 270 Effects of Exercise on Ventilation 469 Focus on Diabetes 318 Role of Sensory Receptors 492 Diabetes Mellitus 346 Recruiting Respiratory Reserve Capacities 497 Focus on Diabetes 363 Sweating, Rehydration, and Water Balance 535 Diabetes and Cardiovascular Disease 445 The Role of Diet 579 Diabetes Insipidus 544 Energy Metabolism 608 Obesity and Diabetes 590 Gender Differences 642 Diabetes Mellitus 615 Leukocyte Mobilization 672 Gestational Diabetes 661 Glucose Transport in Exercising Muscle and Diabetes 716  1 Introduction to Physiology Colored scanning electron micrograph (SEM) of a neuron (nerve cell). The human body is capable of surviving in a CHAPTER OUTLINE dazzling variety of environmental conditions. It can live in jungles, 1.1 Organization of the Body 2 mountains, crowded cities, or deserts. It can withstand the heat 1.2 Homeostasis: A Central of a summer in India or the cold of a New England winter. With Organizing Principle proper training, it can acclimate to altitude changes while scaling of Physiology 9 Mount Everest or survive running a 26.2-mile marathon. 1.3 The Diabetes Epidemic 13 How does the human body do it? As you will learn in this chapter—and throughout this textbook—our bodies have a remarkable ability to adapt to changes in the environment, thereby minimizing internal changes. For example, when a person travels from a cold environment into a warm one (which raises the body’s temperature), the body quickly responds by sweating and increasing blood flow to the skin to help bring the temperature back to normal. The body’s ability to maintain a normal internal environment, called homeostasis, is a primary theme throughout this text. Welcome to the study of human physiology. Go to MasteringA&P for helpful A&P Flix 3-D animations, chapter quizzes, pre-tests, Interactive Physiology tutorials, and more! 2 CHAPTER 1 Introduction to Physiology LEARNING OUTCOMES After studying this chapter, you should be able to: Name the four major types of cells in the human body, and Describe the role of negative feedback in homeostasis. describe their defining characteristics. Explain why diabetes is considered an epidemic. Describe the distribution of water in the body, and define the different body fluid compartments. Define homeostasis and explain its significance to the function of the body. P hysiology, the study of the functions of organisms, comes to strip away all unnecessary details so that the essentials—that is, in many forms—plant physiology, cell physiology, micro- the unifying themes and principles—can be seen more clearly. To bial physiology, and animal physiology, to name a few. This get an idea of what this means, consider Figure 1.1. The brain con- book focuses on human physiology, the study of how our bodies tains billions of cells that are classified into four groups according to work. We emphasize normal physiology, but occasionally describe differences in their four general shapes (morphologies). When you pathophysiology—what happens when normal body function consider the function of these cells, however, the similarities among is disrupted—to better demonstrate typical body function. For them outweigh the differences, allowing them to be grouped into example, the effects of diabetes on body function are described just one category: All cells in this category are specialized to trans- throughout the book to illustrate the delicacy of body function and mit information in the form of electrical signals from one body loca- the interdependency of organ systems. tion to another. Because of this shared function, all these cells are In this book, we take the systems approach to physiology; that classified as neurons (or nerve cells). is, we study one organ system at a time. An organ system is a col- Just as the body’s underlying simplicity is one of physiology’s lection of anatomical structures that work together to carry out a major themes, so is the degree of interaction among its various specific function. For example, the cardiovascular system functions parts. Although each of the body’s cells (cells are the smallest liv- to deliver oxygen- and nutrient-rich blood to the various organs ing units) is independently capable of carrying out its own basic life of the body. We will learn more about organ systems shortly. As we processes, the various types of cells are specialized to perform dif- use the systems approach to studying physiology, you must remem- ferent functions important to the operation of the body as a whole. ber that a single system cannot function alone. Thus a chapter on For this reason, all the cells ultimately depend on one another for the urinary system will include some discussion of the cardiovascu- their survival. Similarly, the body’s organs are specialized to perform lar system, because the two systems interact. certain tasks vital to the operation of other organs. You know, for ex- Because nearly everyone is curious about how the human ample, that your cells need oxygen to live and that oxygen is deliv- body works, we hope that studying physiology will be one of your ered to your cells by the bloodstream, but consider some of the many most satisfying academic experiences. You will also come to real- things that must occur to ensure that oxygen delivery is sufficient to ize that physiology, like the other sciences, is not just a collection meet the cells’ needs. Oxygen is carried in the bloodstream by cells of well-worn facts but rather a work in progress. You will recognize called erythrocytes, which are manufactured by bone marrow, a tis- that there are significant gaps in our understanding of how the body sue found inside certain bones. To ensure that adequate numbers of works, and you will see that much of our current understanding is erythrocytes are present in the blood, the synthesis of these cells is subject to change as new discoveries are made. regulated by a hormone called erythropoietin, which is secreted by Regardless of your background or current interests, your study the kidneys. To ensure adequate blood flow to the body’s tissues, the of physiology will broaden your scientific outlook. You will begin to heart must pump a sufficient volume of blood every minute, and for see the “big picture,” understanding body function not as a collec- this reason the rate and force of its contractions are regulated by the tion of unrelated phenomena but rather as a connected whole. You nervous system. To ensure that the blood carries enough oxygen, might even discover something else—that physiology is beautiful. the lungs must take in sufficient quantities of air, which requires the Most of us who have decided to make it our life’s work think so. control of breathing muscles (such as the diaphragm) by the nervous system. Finally, to provide the energy necessary to drive these and other processes, the gastrointestinal system breaks ingested food 1.1 Organization of the Body down into smaller molecules, which are absorbed into the blood- If you have ever spent time examining a detailed anatomical chart stream and distributed to cells throughout the body. or model of the human body, you have seen that it is an exceedingly This example shows that proper body function requires not complex and intricate structure. Despite the complexity of its struc- only that each part be able to carry out its own particular function, ture, however, an underlying simplicity characterizes the function but also that the parts be able to work together in a coordinated of the human body. manner. To help you better understand how the body’s parts work To a student, perhaps the most interesting thing about the body together, the remainder of the chapter outlines broad principles is that its operation can be explained in terms of a relatively small set pertaining to body function in general; the functions of specific of principles. For this reason, our approach to describing the body is organs and organ systems are the topics of later chapters.  CHAPTER 1 Introduction to Physiology 3 Purkinje cell Pyramidal cell Stellate cell Basket cell Figure 1.1 Shapes of cells found in the brain. Each of these four cells is a neuron that transmits electrical and chemical signals. Cells, Tissues, Organs, and cells. Certain neurons, such as those in the eyes that respond to light or those in the skin that respond to touch, receive informa- Organ Systems tion from the outside environment and allow us to perceive the The human body is a remarkable structure consisting of cells world through our senses. Other neurons relay signals to muscles, arranged in an orderly fashion. Cells are grouped together to form glands, and other organs, enabling the control of movement, hor- tissues, which in turn are grouped together to form organs. Organs mone secretion, and other bodily functions. Still other neurons, work together as organ systems. We now describe each of these such as those in the brain, process information, enabling us to hierarchical components. conceptualize, remember, formulate plans of action, and experi- ence emotion. Cells and Tissues Muscle cells, or muscle fibers (Figure 1.2b), are specialized Although more than 200 distinguishable kinds of cells are present in to contract, thereby generating mechanical force and movement. the body, there are only four major classes: (1) neurons, (2) muscle These cells are found in the muscles of the arms, legs, and other cells, (3) epithelial cells, and (4) connective tissue cells. Representative body parts whose movements are under voluntary control (called cells belonging to each of these cell types are shown in Figure 1.2. skeletal muscle), but they are also found in structures not under vol- These classifications are very broad and are based primarily on func- untary control, such as the heart (cardiac muscle) and blood vessels tional differences. Other, more rigorous ways to classify cells have (smooth muscle). The flexing of an arm, the pumping of blood by been developed based on anatomical distinctions and embryologi- the heart, and the mixing of food in the stomach are all examples of cal origins. muscle cells in action. As mentioned previously, nerve cells, or neurons (Figure 1.2a), Epithelial cells are found in tissues called epithelia (singu- are specialized to transmit information in the form of electri- lar: epithelium), which consist of a continuous, sheetlike layer of cal signals. For this purpose, neurons typically possess branches cells in combination with a thin underlying layer of noncellular that function to receive signals from or transmit signals to other material called a basement membrane (Figure 1.2c). Depending 4 CHAPTER 1 Introduction to Physiology Skeletal muscle cell Smooth muscle cells Cardiac muscle cells (b) Muscle cells (a) Neurons Blood cells Basement membrane Bone cells Basement membrane Lumen Basement membrane Fibroblasts (c) Epithelial cells (in skin and other tissues) Figure 1.2 Major cell types in the human body. (a) Neurons. (b) Muscle cells. (c) Epithelial cells. (d) Connective tissue cells. on the epithelium in question, the cell layer may be one cell thick (simple) or several cells thick (stratified), and the cells may vary (d) Connective tissue cells in shape from short and flattened (squamous), to regular square- shaped (cuboidal), and in some cases to tall and oblong (colum- nar). In all cases, however, cells join closely together to form a are distinguished: exocrine and endocrine. Exocrine glands barrier that prevents material on one side of the epithelium from secrete a product into a duct leading to the external environment mixing freely with material on the other side. Appropriately, epi- (Figure 1.3a). Examples of exocrine glands include sweat glands thelia are found wherever body fluids must be kept separate from and salivary glands. Endocrine glands secrete hormones, chemi- the external environment, such as the skin surface or the lining cals that communicate a message to cells of the body, into the of the lungs. Epithelia are also found in the linings of hollow or- bloodstream (Figure 1.3b). Examples of endocrine glands include gans such as the stomach, intestines, and blood vessels, where the pituitary gland and adrenal gland. they separate fluids in the interior cavity from the surrounding The last remaining major cell type, connective tissue cells, is body fluids. The interior cavity of a hollow organ or vessel is gener- the most diverse. This cell type includes blood cells, bone cells, fat ally referred to as the lumen. cells, and many other kinds of cells that seem to have little in com- Certain epithelial cells are specialized to transport specific ma- mon in terms of structure or function (Figure 1.2d). terials, such as inorganic ions, organic molecules, or water, from In a narrow sense, the term “connective tissue” refers to any one location to another. For example, cells in the lining of the stom- structure whose primary function is to provide physical support ach transport acid (hydrogen ions) into the lumen of the stomach for other structures, to anchor them in place, or to link them to- to aid in the digestion of food. Cells in the lining of the intestine, in gether. Familiar examples of connective tissue structures are ten- comparison, transport nutrients and water from the lumen of the dons, which anchor muscles to bones; ligaments, which connect intestine into the bloodstream. bones together; and the elastic tissue in the skin that gives it its Some epithelial cells form glands, organs specialized in toughness and flexibility. Another example of a connective tissue the synthesis and secretion of a product. Two types of glands is the bones themselves, which provide direct or indirect support  CHAPTER 1 Introduction to Physiology 5 External environment External environment Epithelium Blood vessel Secretory Duct cells Blood flow Secretory cells Hormone (a) Exocrine gland (b) Endocrine gland Figure 1.3 Glands. (a) Exocrine gland. The secretory cells release their product, which travels via a duct to the external environment. (b) Endocrine gland. The secretory cells release their product, a hormone, into the bloodstream, which transports the hormone throughout the internal environment. for all of the body’s structures. In most cases, connective tissue connective tissue (which makes up the heart’s valves and other tis- consists of widely scattered cells embedded in a mass of noncel- sues that hold the muscle fibers together). lular material called the extracellular matrix, which contains a The various organs are organized into organ systems, collec- dense meshwork of proteins and other large molecules. Among tions of organs that work together to perform certain functions. An the most important constituents of the extracellular matrix are the example is the cardiovascular system, whose function is to deliver long, fibrous proteins elastin (which gives the tissue elasticity) and blood to all the body’s tissues. The cardiovascular system includes collagen (which gives the tissue tensile strength—that is, the abil- the heart, blood vessels, and the blood (which is not an organ, ity to resist stretching). but rather a tissue). Another organ system is the gastrointestinal In a broader sense, the term “connective tissue” encompasses system, whose function is to break down food into smaller mol- fluids such as the blood and lymph, which do not provide struc- ecules and then transport these molecules into the bloodstream. tural support like other connective tissue but instead serve to “con- This organ system includes the mouth, salivary glands, esophagus, nect” the various parts of the body together by providing avenues of stomach, intestines, liver, gallbladder, and pancreas. In some or- communication. The blood, for example, delivers oxygen from the gan systems (for example, the cardiovascular and gastrointestinal lungs to the rest of the body’s tissues and carries hormones from the systems), the organs are physically connected. In other cases, the glands that secrete them to the tissues that respond to them. Simi- organs are disconnected and more widely scattered. This is true larly, the lymph carries water and other materials that leak out of of the endocrine system, which encompasses all the glands in the blood vessels throughout the body and returns them to the blood. body that secrete hormones, and the immune system, which pro- It is a general rule that cells of a given type tend to cluster to- tects the body from invading microorganisms and other foreign gether in the body with cells of the same type. Nerve cells, for ex- materials. The body’s organ systems and their primary functions ample, are always found in conjunction with other nerve cells, and are listed in Table 1.1. epithelial cells are always joined with other epithelial cells. Any Although the concept of an organ system is simple in princi- such collection of cells performing similar functions is referred to ple, the distinction between one organ system and another is not as a tissue. Thus tissues are also classified into four basic groups: always clear-cut—many organs perform functions that are integral nervous tissue, muscle tissue, epithelial tissue, and connective tissue. to more than one organ system. A prime example is the pancreas, (The term “tissue” is also used more loosely to refer to any of the which is considered to be part of both the digestive system, because materials of which the body is composed.) it secretes fluid and digestive enzymes into the intestines, and the endocrine system, because it secretes certain hormones. Organs and Organ Systems Generally, when two or more tissues combine to make up struc- Quick Check 1.1 tures that perform particular functions, those structures are called ➊ Define physiology. organs. The heart, for example, is an organ whose primary function is to pump blood. Although composed mostly of muscle tissue, it ❷ Name and describe the four basic types of cells and tissues. also contains nervous tissue (the endings of nerves that control the ❸ Name the ten organ systems, and briefly state the function heartbeat), epithelial tissue (which lines the heart’s chambers), and of each. 6 CHAPTER 1 Introduction to Physiology TABLE 1.1 Organ Systems System Some organs/tissues within system Function Endocrine Hypothalamus, pituitary gland, adrenal gland, Provide communication between cells of the body through the release thyroid gland, parathyroid glands, thymus, pancreas of hormones into the bloodstream Nervous Brain, spinal cord, peripheral nerves Provide communication between cells of the body through electrical signals and the release of neurotransmitters into small gaps between certain cells Musculoskeletal Skeletal muscle, bones, tendons, ligaments Support the body; allow voluntary movement of the body; allow facial expressions Cardiovascular Heart, blood vessels, blood Transport molecules throughout the body in the bloodstream Respiratory Lungs, pharynx, trachea, bronchi Bring oxygen into the body and eliminate carbon dioxide from the body Urinary Kidneys, ureters, bladder, urethra Filter the blood to regulate acidity, blood volume, and ion concentrations; eliminate wastes Gastrointestinal Mouth, esophagus, stomach, small intestine, large Break down food and absorb it into the body intestine, liver, pancreas, gallbladder Reproductive Gonads, reproductive tracts and glands Generate offspring Immune White blood cells, thymus, lymph nodes, spleen, Defend the body against pathogens and abnormal cells tonsils, adenoids Integumentary Skin Protects the body from the external environment The Overall Body Plan: surface of the skin and the inside surfaces of the lungs, gastroin- testinal system, and kidney tubules. They are all part of the same A Simplified View “fabric,” if you will. When