Twelfth Edition Biology Kenneth A. Mason University of Iowa Jonathan B. Losos William H. Danforth Distinguished University Professor and Director, Living Earth Collaborative, Washington University Tod Duncan University of Colorado Denver Contributor: Charles J. Welsh Duquesne University Based on the work of Peter H. Raven President Emeritus, Missouri Botanical Garden; George Engelmann Professor of Botany Emeritus, Washington University George B. Johnson Professor Emeritus of Biology, Washington University rav69618_FM_i-xxii.indd 1 12/11/18 7:24 PM BIOLOGY, TWELFTH EDITION Published by McGraw-Hill Education, 2 Penn Plaza, New York, NY 10121. Copyright © 2020 by McGraw-Hill Education. All rights reserved. Printed in the United States of America. Previous editions © 2017, 2014, and 2011. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written consent of McGraw-Hill Education, including, but not limited to, in any network or other electronic storage or transmission, or broadcast for distance learning. Some ancillaries, including electronic and print components, may not be available to customers outside the United States. This book is printed on acid-free paper. 1 2 3 4 5 6 7 8 9 LWI 21 20 19 ISBN 978-1-260-16961-4 (bound edition) MHID 1-260-16961-8 (bound edition) ISBN 978-1-260-49470-9 (loose-leaf edition) MHID 1-260-49470-5 (loose-leaf edition) Portfolio Managers: Andrew Urban, Michelle Vogler Product Developers: Elizabeth Sievers, Joan Weber Marketing Manager: Kelly Brown Content Project Managers: Kelly Hart, Brent dela Cruz, Sandy Schnee Buyer: Susan K. Culbertson Design: David W. Hash Content Licensing Specialists: Lori Hancock Cover Image: (Diatom) ©Steve Gschmeissner/Science Photo Library/Getty Images; (Leaf): ©Lee Chee Keong/EyeEm/Getty Images; (Rhinoceros): ©GlobalP/iStock/Getty Images Plus; (Beetle): ©kuritafsheen/ooM/Getty Images; (Chameleon): ©SensorSpot/E+/Getty Images; (DNA): ©Doug Struthers/The Image Bank/Getty Images; (Jellyfish): ©Raghu_Ramaswamy/iStock/Getty Images Plus Compositor: MPS Limited All credits appearing on page or at the end of the book are considered to be an extension of the copyright page. Library of Congress Cataloging-in-Publication Data Mason, Kenneth A., author. | Losos, Jonathan B., author. | Duncan, Tod, author. Biology / Kenneth A. Mason, University of Iowa, Jonathan B. Losos, Washington University, Tod Duncan, University of Colorado, Denver; contributors, Charles J. Welsh, Duquesne University. Twelfth edition. | New York, NY : McGraw-Hill Education, [2020] | “Based on the work of Peter H. Raven, President Emeritus, Missouri Botanical Garden; George Engelmann, Professor of Botany Emeritus, Washington University, George B. Johnson, Professor Emeritus of Biology, Washington University.” | Includes index. LCCN 2018036968| ISBN 9781260169614 (alk. paper) | ISBN 9781260565959 LCSH: Biology—Textbooks. LCC QH308.2 .R38 2020 | DDC 570—dc23 LC record available at https://lccn.loc.gov/2018036968 The Internet addresses listed in the text were accurate at the time of publication. The inclusion of a website does not indicate an endorsement by the authors or McGraw-Hill Education, and McGraw-Hill Education does not guarantee the accuracy of the information presented at these sites. mheducation.com/highered rav69618_FM_i-xxii.indd 2 12/11/18 7:24 PM Brief Contents Committed to Excellence xi 27 Prokaryotes 557 Preparing Students for the Future xv 28 Protists 584 29 Seedless Plants 608 30 Seed Plants 623 31 Fungi 641 I Part The Molecular Basis of Life 1 32 Animal Diversity and the Evolution of Body Plans 664 33 Protostomes 687 1 The Science of Biology 1 34 Deuterostomes 720 2 The Nature of Molecules and the Properties of Water 18 3 The Chemical Building Blocks of Life 35 Part VI Plant Form and Function 762 II Part Biology of the Cell 63 35 Plant Form 762 36 Transport in Plants 788 4 Cell Structure 63 37 Plant Nutrition and Soils 807 5 Membranes 92 38 Plant Defense Responses 825 6 Energy and Metabolism 112 39 Sensory Systems in Plants 838 7 How Cells Harvest Energy 128 40 Plant Reproduction 866 8 Photosynthesis 154 9 Cell Communication 176 Part VII Animal Form and Function 900 10 How Cells Divide 194 41 The Animal Body and Principles of Regulation 900 III Part Genetic and Molecular Biology 217 42 The Nervous System 924 43 Sensory Systems 955 11 Sexual Reproduction and Meiosis 217 44 The Endocrine System 982 12 Patterns of Inheritance 231 45 The Musculoskeletal System 1006 13 Chromosomes, Mapping, and the Meiosis–Inheritance 46 The Digestive System 1026 Connection 250 47 The Respiratory System 1047 14 DNA: The Genetic Material 268 48 The Circulatory System 1066 15 Genes and How They Work 290 49 Osmotic Regulation and the Urinary System 1088 16 Control of Gene Expression 317 50 The Immune System 1106 17 Biotechnology 340 51 The Reproductive System 1135 18 Genomics 366 52 Animal Development 1157 19 Cellular Mechanisms of Development 389 VIII Part Ecology and Behavior 1188 IV Part Evolution 416 53 Behavioral Biology 1188 20 Genes Within Populations 416 54 Ecology of Individuals and Populations 1218 21 The Evidence for Evolution 443 55 Community Ecology 1242 22 The Origin of Species 463 56 Dynamics of Ecosystems 1265 23 Systematics, Phylogenies, and Comparative Biology 484 57 The Biosphere and Human Impacts 1289 24 Genome Evolution 504 58 Conservation Biology 1318 V Appendix A Part Diversity of Life on Earth 523 Glossary G-1 25 The Origin and Diversity of Life 523 Index I-1 26 Viruses 537 iii rav69618_FM_i-xxii.indd 3 12/11/18 7:24 PM About the Authors Kenneth Mason maintains an association with the University of Iowa, Department of Biology after having served as a faculty member for eight years. His academic positions, as a teacher and researcher, include the faculty of the University of Kansas, where he designed and established the genetics lab, and taught and published on the genetics of pigmentation in amphibians. At Purdue University, he successfully developed and grew large intro- ductory biology courses and collaborated with other faculty in an innovative biology, chemistry, and physics course supported by the National Science Foundation. At the University of Iowa, where his wife served as ©Kenneth Mason president of the university, he taught introductory biology and human genetics. His honor society memberships include Phi Sigma, Alpha Lambda Delta, and, by vote of Purdue pharmacy students, Phi Eta Sigma Freshman Honors Society. Jonathan Losos is the William H. Danforth Distinguished University Professor in the Department of Biology at Washington University and Director of the Living Earth Collaborative, a partnership between the university, the Saint Louis Zoo and the Missouri Botanical Garden. Losos’s research has focused on studying patterns of adaptive radiation and evolutionary diversification in lizards. He is a member of the National Academy of Sciences, a fellow of the American Academy of Arts and Science, and the recipient of several awards, including the Theodosius Dobzhanksy and David Starr Jordan Prizes, the Edward Osborne Wilson Naturalist ©Jonathan Losos Award, and the Daniel Giraud Elliot Medal, as well as receiving fellowships from the John Guggenheim and David and Lucile Packard Foundations. Losos has published more than 200 scientific articles and has written two books, Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles (University of California Press, 2009) and Improbable Destinies: Fate, Chance, and the Future of Evolution (Penguin-Random House, 2017). Tod Duncan is a Clinical Assistant Professor at the University of Colorado Denver. He currently teaches first semester general biology and coordinates first and second semester general biology laboratories. Previously, he taught general microbiology, virology, the biology of cancer, medical microbiology, and cell biology. A bachelor’s degree in cell biology with an emphasis on plant molecular and cellular biology from the University of East Anglia in England led to doctoral studies in cell cycle control, and postdoctoral research on the molecular and biochemical mechanisms of DNA alkylation damage in vitro and in Drosophila melanogaster. Currently, he is interested in factors affecting retention ©Lesley Howard and success of incoming first-year students in diverse demographics. He lives in Boulder, Colorado, with his two Great Danes, Eddie and Henry. iv rav69618_FM_i-xxii.indd 4 12/11/18 7:24 PM Contents Committed to Excellence xi 4.4 The Endomembrane System 73 Preparing Students for the Future xv 4.5 Mitochondria and Chloroplasts: Cellular Generators 77 4.6 The Cytoskeleton 79 4.7 Extracellular Structures and Cell Movement 83 ©Soames Summerhays/Natural Visions 4.8 Cell-to-Cell Interactions 86 5 Membranes 92 I The Molecular Basis Part 5.1 The Structure of Membranes 92 5.2 Phospholipids: The Membrane’s Foundation 96 of Life 5.3 Proteins: Multifunctional Components 98 5.4 Passive Transport Across Membranes 100 1 The Science of Biology 1 5.5 Active Transport Across Membranes 103 5.6 Bulk Transport by Endocytosis and Exocytosis 106 1.1 The Science of Life 1 1.2 The Nature of Science 4 6 Energy and Metabolism 112 1.3 An Example of Scientific Inquiry: Darwin and 6.1 The Flow of Energy in Living Systems 113 Evolution 8 6.2 The Laws of Thermodynamics and 1.4 Core Concepts in Biology 12 Free Energy 114 2 The Nature of Molecules and the 6.3 ATP: The Energy Currency of Cells 117 6.4 Enzymes: Biological Catalysts 118 Properties of Water 18 6.5 Metabolism: The Chemical Description of Cell 2.1 The Nature of Atoms 19 Function 122 2.2 Elements Found in Living Systems 23 7 How Cells Harvest Energy 128 2.3 The Nature of Chemical Bonds 24 2.4 Water: A Vital Compound 26 7.1 Overview of Respiration 129 2.5 Properties of Water 29 7.2 Glycolysis: Splitting Glucose 133 2.6 Acids and Bases 30 7.3 The Oxidation of Pyruvate Produces Acetyl-CoA 136 3 The Chemical Building Blocks of Life 35 7.4 The Citric Acid Cycle 137 7.5 The Electron Transport Chain and 3.1 Carbon: The Framework of Biological Molecules 36 Chemiosmosis 140 3.2 Carbohydrates: Energy Storage and Structural 7.6 Energy Yield of Aerobic Respiration 143 Molecules 40 7.7 Regulation of Aerobic Respiration 144 3.3 Nucleic Acids: Information Molecules 43 7.8 Oxidation Without O 145 3.4 Proteins: Molecules with Diverse Structures and 2 Functions 46 7.9 Catabolism of Proteins and Fats 147 3.5 Lipids: Hydrophobic Molecules 56 7.10 Evolution of Metabolism 149 8 Photosynthesis 154 ©Dr. Gopal Murti/Science Source 8.1 Overview of Photosynthesis 154 II Biology of the Cell 8.2 The Discovery of Photosynthetic Part Processes 156 8.3 Pigments 158 4 Cell Structure 63 8.4 Photosystem Organization 161 4.1 Cell Theory 63 8.5 The Light-Dependent Reactions 163 4.2 Prokaryotic Cells 67 8.6 Carbon Fixation: The Calvin Cycle 167 4.3 Eukaryotic Cells 69 8.7 Photorespiration 170 v rav69618_FM_i-xxii.indd 5 12/11/18 7:24 PM 9 Cell Communication 176 14 DNA: The Genetic Material 268 9.1 Overview of Cell Communication 176 14.1 The Nature of the Genetic Material 268 9.2 Receptor Types 179 14.2 DNA Structure 271 9.3 Intracellular Receptors 181 14.3 Basic Characteristics of DNA Replication 275 9.4 Signal Transduction Through Receptor 14.4 Prokaryotic Replication 278 Kinases 182 14.5 Eukaryotic Replication 283 9.5 Signal Transduction Through G Protein–Coupled 14.6 DNA Repair 285 Receptors 186 15 Genes and How They Work 290 10 How Cells Divide 194 15.1 The Nature of Genes 290 10.1 Bacterial Cell Division 195 15.2 The Genetic Code 293 10.2 Eukaryotic Chromosomes 197 15.3 Prokaryotic Transcription 296 10.3 Overview of the Eukaryotic Cell Cycle 200 15.4 Eukaryotic Transcription 299 10.4 Interphase: Preparation for Mitosis 201 15.5 Eukaryotic pre-mRNA Splicing 301 10.5 M Phase: Chromosome Segregation and the Division of Cytoplasmic Contents 203 15.6 The Structure of tRNA and Ribosomes 303 10.6 Control of the Cell Cycle 206 15.7 The Process of Translation 305 10.7 Genetics of Cancer 211 15.8 Summarizing Gene Expression 309 15.9 Mutation: Altered Genes 311 ©Steven P. Lynch 16 Control of Gene Expression 317 III Genetic and Molecular 16.1 Control of Gene Expression 317 Part 16.2 Regulatory Proteins 318 16.3 Prokaryotic Regulation 321 Biology 16.4 Eukaryotic Regulation 325 16.5 Chromatin Structure Affects Gene Expression 328 11 Sexual Reproduction and Meiosis 217 16.6 Eukaryotic Posttranscriptional Regulation 330 11.1 Sexual Reproduction Requires Meiosis 217 16.7 Protein Degradation 334 11.2 Features of Meiosis 219 17 Biotechnology 340 11.3 The Process of Meiosis 220 11.4 Summing Up: Meiosis Versus Mitosis 225 17.1 Recombinant DNA 340 17.2 Amplifying DNA Using the Polymerase Chain 12 Patterns of Inheritance 231 Reaction 345 17.3 Creating, Correcting, and Analyzing Genetic 12.1 The Mystery of Heredity 231 Variation 348 12.2 Monohybrid Crosses: The Principle of 17.4 Constructing and Using Transgenic Organisms 350 Segregation 234 17.5 Environmental Applications 354 12.3 Dihybrid Crosses: The Principle of Independent Assortment 238 17.6 Medical Applications 356 12.4 Probability: Predicting the Results of Crosses 240 17.7 Agricultural Applications 360 12.5 The Testcross: Revealing Unknown Genotypes 241 18 Genomics 366 12.6 Extensions to Mendel 242 18.1 Mapping Genomes 366 13 Chromosomes, Mapping, and 18.2 Sequencing Genomes 370 the Meiosis–Inheritance 18.3 Genome Projects 373 Connection 250 18.4 Genome Annotation and Databases 374 18.5 Comparative and Functional Genomics 378 13.1 Sex Linkage and the Chromosomal Theory of 18.6 Applications of Genomics 383 Inheritance 251 13.2 Sex Chromosomes and Sex Determination 252 19 Cellular Mechanisms of 13.3 Exceptions to the Chromosomal Theory of Development 389 Inheritance 255 13.4 Genetic Mapping 255 19.1 The Process of Development 389 13.5 Human Genetic Disorders 260 19.2 Cell Division 390 vi Contents rav69618_FM_i-xxii.indd 6 12/11/18 7:25 PM 19.3 Cell Differentiation 392 23.3 Systematics and Classification 489 19.4 Nuclear Reprogramming 397 23.4 Phylogenetics and Comparative Biology 493 19.5 Pattern Formation 400 23.5 Phylogenetics and Disease Evolution 499 19.6 E volution of Pattern Formation 406 24 Genome Evolution 504 19.7 Morphogenesis 409 24.1 Comparative Genomics 504 ©tamoncity/Shutterstock 24.2 Genome Size 508 24.3 Evolution Within Genomes 511 IV 24.4 Gene Function and Expression Patterns 515 Evolution Part 24.5 Applying Comparative Genomics 516 20 Genes Within Populations 416 ©Jeff Hunter/Getty Images 20.1 Genetic Variation and Evolution 416 V 20.2 Changes in Allele Frequency 418 Diversity of Life Part 20.3 Five Agents of Evolutionary Change 420 20.4 Quantifying Natural Selection 425 on Earth 20.5 Reproductive Strategies 426 20.6 Natural Selection’s Role in Maintaining Variation 430 25 The Origin and Diversity 20.7 Selection Acting on Traits Affected by Multiple of Life 523 Genes 432 20.8 Experimental Studies of Natural Selection 434 25.1 Deep Time 525 20.9 Interactions Among Evolutionary Forces 436 25.2 Origins of Life 525 20.10 The Limits of Selection 437 25.3 Evidence for Early Life 528 25.4 Earth’s Changing System 530 21 The Evidence for Evolution 443 25.5 Ever-Changing Life on Earth 531 21.1 The Beaks of Darwin’s Finches: Evidence of Natural 26 Viruses 537 Selection 444 21.2 Peppered Moths and Industrial Melanism: More Evidence 26.1 The Nature of Viruses 538 of Selection 446 26.2 Viral Diversity 542 21.3 Artificial Selection: Human-Initiated 26.3 Bacteriophage: Bacterial Viruses 544 Change 448 26.4 Viral Diseases of Humans 546 21.4 Fossil Evidence of Evolution 450 26.5 Prions and Viroids: Infectious Subviral 21.5 Anatomical Evidence for Evolution 454 Particles 552 21.6 Convergent Evolution and the Biogeographical Record 456 27 Prokaryotes 557 21.7 Darwin’s Critics 458 27.1 Prokaryotic Diversity 558 22 The Origin of Species 463 27.2 Prokaryotic Cell Structure 562 22.1 The Nature of Species and the Biological Species 27.3 Prokaryotic Genetics 567 Concept 463 27.4 The Metabolic Diversity of Prokaryotes 571 22.2 Natural Selection and Reproductive Isolation 468 27.5 Microbial Ecology 573 22.3 The Role of Genetic Drift and Natural Selection in 27.6 Bacterial Diseases of Humans 575 Speciation 469 22.4 The Geography of Speciation 471 28 Protists 584 22.5 Adaptive Radiation and Biological Diversity 473 28.1 Eukaryotic Origins and Endosymbiosis 584 22.6 The Pace of Evolution 478 28.2 Overview of Protists 587 22.7 Speciation and Extinction Through Time 479 28.3 Characteristics of the Excavata 589 23 Systematics, Phylogenies, and 28.4 Characteristics of the Chromalveolata 592 28.5 Characteristics of the Rhizaria 598 Comparative Biology 484 28.6 Characteristics of the Archaeplastida 599 23.1 Systematics 484 28.7 Characteristics of the Amoebozoa 602 23.2 Cladistics 486 28.8 Characteristics of the Opisthokonta 603 Contents vii rav69618_FM_i-xxii.indd 7 12/11/18 7:25 PM 29 Seedless Plants 608 34 Deuterostomes 720 29.1 Origin of Land Plants 608 34.1 Echinoderms 721 29.2 Bryophytes Have a Dominant Gametophyte 34.2 Chordates 723 Generation 611 34.3 Nonvertebrate Chordates 725 29.3 Tracheophytes Have a Dominant Sporophyte 34.4 Vertebrate Chordates 726 Generation 613 34.5 Fishes 728 29.4 Lycophytes Diverged from the Main Lineage 34.6 Amphibians 733 of Vascular Plants 616 34.7 Reptiles 737 29.5 Pterophytes Are the Ferns and Their Relatives 617 34.8 Birds 742 34.9 Mammals 746 30 Seed Plants 623 34.10 Evolution of the Primates 751 30.1 The Evolution of Seed Plants 623 30.2 Gymnosperms: Plants with “Naked Seeds” 624 ©Susan Singer 30.3 Angiosperms: The Flowering Plants 628 VI 30.4 Seeds 634 Plant Form and Part 30.5 Fruits 635 Function 31 Fungi 641 31.1 Classification of Fungi 642 35 Plant Form 762 31.2 Fungal Forms, Nutrition, and Reproduction 643 31.3 Fungal Ecology 646 35.1 Organization of the Plant Body: An Overview 763 31.4 Fungal Parasites and Pathogens 650 35.2 Plant Tissues 766 31.5 Basidiomycota: The Club (Basidium) 35.3 Roots: Anchoring and Absorption Structures 772 Fungi 652 35.4 Stems: Support for Above-Ground Organs 776 31.6 Ascomycota: The Sac (Ascus) Fungi 654 35.5 Leaves: Photosynthetic Organs 781 31.7 Glomeromycota: Asexual Plant Symbionts 656 31.8 Zygomycota: Zygote-Producing Fungi 656 36 Transport in Plants 788 31.9 Chytridiomycota and Relatives: Fungi with Zoospores 658 36.1 Transport Mechanisms 789 31.10 Microsporidia: Unicellular Parasites 659 36.2 Water and Mineral Absorption 792 36.3 Xylem Transport 795 32 Animal Diversity and the Evolution 36.4 Rate of Transpiration 797 of Body Plans 664 36.5 Water-Stress Responses 799 36.6 Phloem Transport 801 32.1 Some General Features of Animals 664 32.2 Evolution of the Animal Body Plan 666 37 Plant Nutrition and Soils 807 32.3 Animal Phylogeny 670 37.1 Soils: The Substrates on Which Plants Depend 807 32.4 Parazoa: Animals That Lack Specialized Tissues 674 37.2 Plant Nutrients 811 32.5 Eumetazoa: Animals with True Tissues 677 37.3 Special Nutritional Strategies 813 32.6 The Bilateria 682 37.4 Carbon–Nitrogen Balance and Global Change 816 37.5 Phytoremediation 819 33 Protostomes 687 38 Plant Defense Responses 825 33.1 The Clades of Protostomes 688 38.1 Physical Defenses 825 33.2 Flatworms (Platyhelminthes) 689 38.2 Chemical Defenses 827 33.3 Rotifers (Rotifera) 692 38.3 Animals That Protect Plants 831 33.4 Mollusks (Mollusca) 693 38.4 Systemic Responses to Invaders 832 33.5 Ribbon Worms (Nemertea) 699 33.6 Annelids (Annelida) 700 39 Sensory Systems in Plants 838 33.7 Bryozoans (Bryozoa) and Brachiopods (Brachiopoda) 703 39.1 Responses to Light 838 33.8 Roundworms (Nematoda) 705 39.2 Responses to Gravity 843 33.9 Arthropods (Arthropoda) 707 39.3 Responses to Mechanical Stimuli 845 viii Contents rav69618_FM_i-xxii.indd 8 12/11/18 7:25 PM 39.4 Responses to Water and Temperature 847 44 The Endocrine System 982 39.5 Hormones and Sensory Systems 849 44.1 Regulation of Body Processes by Chemical Messengers 983 40 Plant Reproduction 866 44.2 Overview of Hormone Action 988 40.1 Reproductive Development 867 44.3 The Pituitary and Hypothalamus: The Body’s Control 40.2 Making Flowers 869 Centers 991 40.3 Structure and Evolution of Flowers 874 44.4 The Major Peripheral Endocrine Glands 996 40.4 Pollination and Fertilization 877 44.5 Other Hormones and Their Effects 1000 40.5 Embryo Development 882 45 The Musculoskeletal System 1006 40.6 Germination 888 40.7 Asexual Reproduction 891 45.1 Types of Skeletal Systems 1007 40.8 Plant Life Spans 893 45.2 A Closer Look at Bone 1009 45.3 Joints 1012 ©Dr. Roger C. Wagner, Professor Emeritus of Blologlcal Sciences, University of Delaware 45.4 Muscle Contraction 1013 45.5 Vertebrate Skeleton Evolution and Modes VII of Locomotion 1020 Animal Form and Part 46 The Digestive System 1026 Function 46.1 Types of Digestive Systems 1027 46.2 The Mouth and Teeth: Food Capture and Bulk Processing 1029 41 The Animal Body and Principles 46.3 The Esophagus and the Stomach: The Early Stages of Regulation 900 of Digestion 1030 46.4 The Intestines: Breakdown, Absorption, and 41.1 Organization of Animal Bodies 901 Elimination 1032 41.2 Epithelial Tissue 902 46.5 Accessory Organ Function 1035 41.3 Connective Tissue 905 46.6 Neural and Hormonal Regulation of the Digestive 41.4 Muscle Tissue 908 Tract 1037 41.5 Nerve Tissue 909 46.7 Food Energy, Energy Expenditure, and Essential 41.6 Overview of Vertebrate Organ Systems 910 Nutrients 1038 41.7 Homeostasis 913 46.8 Variations in Vertebrate Digestive Systems 1042 41.8 Regulating Body Temperature 915 47 The Respiratory System 1047 42 The Nervous System 924 47.1 Gas Exchange Across Respiratory Surfaces 1048 47.2 Gills, Cutaneous Respiration, and Tracheal 42.1 Nervous System Organization 925 Systems 1049 42.2 The Mechanism of Nerve Impulse Transmission 928 47.3 Lungs 1052 42.3 Synapses: Where Neurons Communicate with Other 47.4 Structures, Mechanisms, and Control of Ventilation Cells 933 in Mammals 1055 42.4 The Central Nervous System: Brain and 47.5 Transport of Gases in Body Fluids 1059 Spinal Cord 939 42.5 The Peripheral Nervous System: Spinal and Cranial 48 The Circulatory System 1066 Nerves 946 48.1 Invertebrate Circulatory Systems 1066 43 Sensory Systems 955 48.2 The Components of Vertebrate Blood 1068 43.1 Overview of Sensory Receptors 956 48.3 Vertebrate Circulatory Systems 1071 43.2 Thermoreceptors, Nociceptors, and Electromagnetic 48.4 Cardiac Cycle, Electrical Conduction, ECG, Receptors: Temperature, Pain, and Magnetic and Cardiac Output 1074 Fields 958 48.5 Blood Pressure and Blood Vessels 1078 43.3 Mechanoreceptors I: Touch, Pressure, and Body Position 959 49 Osmotic Regulation and the Urinary 43.4 Mechanoreceptors II: Hearing, Vibration, and System 1088 Balance 961 43.5 Chemoreceptors: Taste, Smell, and pH 967 49.1 Osmolarity and Osmotic Balance 1088 43.6 Vision 969 49.2 Nitrogenous Wastes: Ammonia, Urea, and 43.7 Evolution and Development of Eyes 975 Uric Acid 1090 Contents ix rav69618_FM_i-xxii.indd 9 12/11/18 7:25 PM