Animal Physiology

Cover
Front Endpapers: Themes in the Study of Animal Physiology
Front Matter
	Copyright Page
	Dedication
	Preface
		New to this Edition
		Acknowledgments
	To Our Readers
	Media and Supplements to accompany Animal Physiology, Fourth Edition
	Brief Contents
	Contents
PART I Fundamentals of Physiology
Chapter 1 Animals and Environments: Function on the Ecological Stage
	The Importance of Physiology
	The Highly Integrative Nature of Physiology
	Mechanism and Origin: Physiology’s Two Central Questions
		The study of mechanism: How do modern-day animals carry out their functions?
		The study of origin: Why do modern-day animals possess the mechanisms they do?
		Natural selection is a key process of evolutionary origin
		Mechanism and adaptive significance are distinct concepts that do not imply each other
	This Book’s Approach to Physiology
	Animals
		The structural property of an animal that persists through time is its organization
		Most cells of an animal are exposed to the internal environment, not the external environment
		The internal environment may be permitted to change when the external environment changes, or it may be kept constant
		Homeostasis in the lives of animals: Internal constancy is often critical for proper function
		Time in the lives of animals: Physiology changes in five time frames
		Size in the lives of animals: Body size is one of an animal’s most important traits
	Environments
		Earth’s major physical and chemical environments
		The environment an animal occupies is often a microenvironment or microclimate
		Animals often modify their own environments
	Evolutionary Processes
		Some processes of evolution are adaptive, others are not
		A trait is not an adaptation merely because it exists
		Adaptation is studied as an empirical science
		Evolutionary potential can be high or low, depending on available genetic variation
	Individual Variation and the Question of “Personalities” within a Population
	Study Questions
	References
Chapter 2 Molecules and Cells in Animal Physiology
	Cell Membranes and Intracellular Membranes
		The lipids of membranes are structured, diverse, fluid, and responsive to some environmental factors
		Proteins endow membranes with numerous functional capacities
		Carbohydrates play important roles in membranes
	Epithelia
	Elements of Metabolism
	Enzyme Fundamentals
		Enzyme-catalyzed reactions exhibit hyperbolic or sigmoid kinetics
		Maximum reaction velocity is determined by the amount and catalytic effectiveness of an enzyme
		Enzyme–substrate affinity affects reaction velocity at the substrate concentrations that are usual in cells
		Enzymes undergo changes in molecular conformation and have specific binding sites that interact
		Enzymes catalyze reversible reactions in both directions
		Multiple molecular forms of enzymes occur at all levels of animal organization
	Regulation of Cell Function by Enzymes
		The types and amounts of enzymes present depend on gene expression and enzyme degradation
		Modulation of existing enzyme molecules permits fast regulation of cell function
	Evolution of Enzymes
	Enzymes Are Instruments of Change in All Time Frames
	The Life and Death of Proteins
	Light and Color
	Reception and Use of Signals by Cells
		Extracellular signals initiate their effects by binding to receptor proteins
		Cell signal transduction often entails sequences of amplifying effects
		Several second-messenger systems participate in cell signal transduction
	Study Questions
	References
Chapter 3 Genomics, Proteomics, and Related Approaches to Physiology
	Genomics
		Genomics is inextricably linked with advanced methods of information processing
		One overarching goal of genomics is to elucidate the evolution of genes and genomes
		A second overarching goal of genomics is to elucidate the current functioning of genes and genomes
		Genomes must ultimately be related empirically to phenotypes
	Top-down versus Bottom-up Approaches to the Study of Physiology
	Screening or Profiling as a Research Strategy
	The Study of Gene Transcription: Transcriptomics
		Transcription profiling often identifies large numbers of genes that exhibit altered transcription in response to environmental
		Transcription profiling reveals that many genes routinely undergo daily cycles of transcription
		Manipulations of protein synthesis can be used to clarify gene function
	Proteomics
	Metabolomics
	Study Questions
	References
Chapter 4 Physiological Development and Epigenetics
	The Physiology of Immature Animals Always Differs from That of Adults
	Introduction to Phenotypic Plasticity and Epigenetics
	Phenotypic Plasticity during Development
		Environmental effects during development may arise from programmed responses to the environment or may be forced by chemical or
		Insect polyphenic development underlies some of the most dramatic cases of phenotypic plasticity
		Other animals besides insects also sometimes exhibit polyphenic development
	Epigenetics
		Two major mechanisms of epigenetic marking are DNA methylation and covalent modification of histone proteins
		Epigenetic inheritance can be within an individual or transgenerational
		Epigenetic marking plays a key role in tissue differentiation during ordinary development
		Evidence increasingly points to epigenetic control of polyphenic development
		Epigenetic marking may account for lifelong effects of early-life stress
	Study Questions
	References
Chapter 5 Transport of Solutes and Water
	Passive Solute Transport by Simple Diffusion
		Concentration gradients give rise to the most elementary form of simple solute diffusion
		Electrical gradients often influence the diffusion of charged solutes at membranes
		Biological aspects of diffusion across membranes: Some solutes dissolve in the membrane; others require channels
		Diffusion of ions across cell membranes is determined by simultaneous concentration and electrical effects
		Diffusion often creates challenges for cells and animals
		Concentration gradients can create electrical gradients that alter concentration gradients
	Passive Solute Transport by Facilitated Diffusion
	Active Transport
		Active transport and facilitated diffusion are types of carrier-mediated transport
		Basic properties of active-transport mechanisms
		Recognition of active transport completes our overview of a single animal cell
		Primary and secondary active transport differ in their cellular-molecular mechanisms
		Active transport across an epithelium does not imply a specific transport mechanism
		Two epithelial ion-pumping mechanisms help freshwater fish maintain their blood composition
	Diversity and Modulation of Channels and Transporters
	Osmotic Pressure and Other Colligative Properties of Aqueous Solutions
		Physiologists usually express osmotic pressure in osmolar units
		Osmotic pressures can be measured in several ways
	Osmosis
		Quantification and terminology
		Hydrostatic pressures develop from osmotic pressures only when two or more solutions interact
		Water may dissolve in membranes or pass through aquaporin water channels during osmosis
		Aquaporins
		Osmosis and solute physiology often interact
	Study Questions
	References
PART II Food, Energy, and Temperature
Chapter 6 Nutrition, Feeding, and Digestion
	Nutrition
		Proteins are “foremost”
		Lipids are required for all membranes and are the principal storage compounds of animals
		Carbohydrates are low in abundance in many animals but highly abundant when they play structural roles
		Vitamins are essential organic compounds required in small amounts
		Elemental nutrition: Many minerals are essential nutrients
	Feeding
		Many animals feed on organisms that are individually attacked and ingested
		Suspension feeding is common in aquatic animals
		Symbioses with microbes often play key roles in animal feeding and nutrition
	Digestion and Absorption
		Vertebrates, arthropods, and molluscs represent three important digestive–absorptive plans
		Digestion is carried out by specific enzymes operating in three spatial contexts
		Absorption occurs by different mechanisms for hydrophilic and hydrophobic molecules
	Responses to Eating
	The Control of Hunger and Satiation
	Nutritional Physiology in Longer Frames of Time
		Nutritional physiology responds to long-term environmental change
		The nutritional physiology of individuals is often endogenously programmed to change over time: Developmental and clock-driven c
	Study Questions
	References
Chapter 7 Energy Metabolism
	Why Animals Need Energy: The Second Law of Thermodynamics
	Fundamentals of Animal Energetics
		The forms of energy vary in their capacity for physiological work
		Transformations of high-grade energy are always inefficient
		Animals use energy to perform three major functions
	Metabolic Rate: Meaning and Measurement
		Direct calorimetry: The metabolic rate of an animal can be measured directly
		Indirect calorimetry: Animal metabolic rates are usually measured indirectly
	Factors That Affect Metabolic Rates
		Ingestion of food causes metabolic rate to rise
	Basal Metabolic Rate and Standard Metabolic Rate
	Metabolic Scaling: The Relation between Metabolic Rate and Body Size
		Resting metabolic rate is an allometric function of body weight in related species
		The metabolic rate of active animals is often also an allometric function of body weight
		The metabolism–size relation has important physiological and ecological implications
		The explanation for allometric metabolism–size relations remains unknown
	Energetics of Food and Growth
	Conclusion: Energy as the Common Currency of Life
	Postscript: The Energy Cost of Mental Effort
	Study Questions
	References
Chapter 8 Aerobic and Anaerobic Forms of Metabolism
	Mechanisms of ATP Production and Their Implications
		Aerobic catabolism consists of four major sets of reactions
		O2 deficiency poses two biochemical challenges: Impaired ATP synthesis and potential redox imbalance
		Certain tissues possess anaerobic catabolic pathways that synthesize ATP
		Anaerobic glycolysis is the principal anaerobic catabolic pathway of vertebrates
		What happens to catabolic end products?
		The functional roles of ATP-producing mechanisms depend on whether they operate in steady state or nonsteady state
		Phosphagens provide an additional mechanism of ATP production without O2
		Internal O2 stores may be used to make ATP
	Comparative Properties of Mechanisms of ATP Production
		Question 1: What is each mechanism’s total possible ATP yield per episode of use?
		Question 2: How rapidly can ATP production be accelerated?
		Question 3: What is each mechanism’s peak rate of ATP production (peak power)?
		Question 4: How rapidly can each mechanism be reinitialized?
		Conclusion: All mechanisms have pros and cons
	Two Themes in Exercise Physiology: Fatigue and Muscle Fiber Types
		Fatigue has many, context-dependent causes
		The muscle fibers in the muscles used for locomotion are heterogeneous in functional properties
	The Interplay of Aerobic and Anaerobic Catabolism during Exercise
		Metabolic transitions occur at the start and end of vertebrate exercise
		The ATP source for all-out exercise varies in a regular manner with exercise duration
		Related species and individuals within one species are often poised very differently for use of aerobic and anaerobic catabolism
	Responses to Impaired O2 Influx from the Environment
		Air-breathing vertebrates during diving: Preserving the brain presents special challenges
		Animals faced with reduced O2 availability in their usual environments may show conformity or regulation of aerobic ATP synthesi
		Water-breathing anaerobes: Some aquatic animals are capable of protracted life in water devoid of O2
	Study Questions
	References
Chapter 9 The Energetics of Aerobic Activity
	How Active Animals Are Studied
	The Energy Costs of Defined Exercise
		The most advantageous speed depends on the function of exercise
		The minimum cost of transport depends in regular ways on mode of locomotion and body size
	The Maximum Rate of Oxygen Consumption
		VO2max differs among phyletic groups and often from species to species within a phyletic group
		VO2max varies among individuals within a species
		VO2max responds to training and selection
	The Energetics of Routine and Extreme Daily Life
	Long-Distance Migration
	Ecological Energetics
	Study Questions
	References
Chapter 10 Thermal Relations
	Temperature and Heat
	Heat Transfer between Animals and Their Environments
		Conduction and convection: Convection is intrinsically faster
		Evaporation: The change of water from liquid to gas carries much heat away
		Thermal radiation permits widely spaced objects to exchange heat at the speed of light
	Poikilothermy (Ectothermy)
		Poikilotherms often exert behavioral control over their body temperatures
		Poikilotherms must be able to function over a range of body temperatures
		Poikilotherms respond physiologically to their environments in all three major time frames
		Acute responses: Metabolic rate is an approximately exponential function of body temperature
		Chronic responses: Acclimation often blunts metabolic responses to temperature
		The rate–temperature relations and thermal limits of individuals: Ecological decline occurs at milder temperatures than the temp
		Evolutionary changes: Species are often specialized to live at their respective body temperatures
		Temperature and heat matter because they affect the functional states of molecules, as well as the rates of processes
		Poikilotherms threatened with freezing: They may survive by preventing freezing or by tolerating it
	Homeothermy in Mammals and Birds
		Metabolic rate rises in cold and hot environments because of the costs of homeothermy
		The shape of the metabolism–temperature curve depends on fundamental heat-exchange principles
		Homeothermy is metabolically expensive
		Insulation is modulated by adjustments of the pelage or plumage, blood flow, and posture
		Heat production is increased below thermoneutrality by shivering and nonshivering thermogenesis
		Regional heterothermy: In cold environments, allowing some tissues to cool can have advantages
		Countercurrent heat exchange permits selective restriction of heat flow to appendages
		Mammals and birds in hot environments: Their first lines of defense are often not evaporative
		Active evaporative cooling is the ultimate line of defense against overheating
		Mammals and birds acclimatize to winter and summer
		Evolutionary changes: Species are often specialized to live in their respective climates
		Mammals and birds sometimes escape the demands of homeothermy by hibernation, torpor, or related processes
		Human thermoregulation
	Warm-Bodied Fish
	Endothermy and Homeothermy in Insects
		The insects that thermoregulate during flight require certain flight-muscle temperatures to fly
		Solitary insects employ diverse mechanisms of thermoregulation
		Colonies of social bees and wasps often display sophisticated thermoregulation
	Coda
	Study Questions
	References
Chapter 11 Food, Energy, and Temperature AT WORK: The Lives of Mammals in Frigid Places
	Food, Nutrition, Energy Metabolism, and Thermoregulation in the Lives of Adult Reindeer
	Newborn Reindeer
	The Future of Reindeer: Timing and Ice
	Thermoregulatory Development: Small Mammals Compared with Large
	The Effect of Body Size on Mammals’ Lives in Cold Environments: An Overview
	Hibernation as a Winter Strategy: New Directions and Discoveries
		Arctic ground squirrels supercool during hibernation and arouse periodically throughout their hibernation season
		The composition of the lipids consumed before hibernation affects the dynamics of hibernation
		Although periodic arousals detract from the energy savings of hibernation, their function is unknown
		The intersection of sociobiology and hibernation physiology
	Study Questions
	References
Chapter 12 Neurons
	The Physiology of Control: Neurons and Endocrine Cells Compared
		Neurons transmit electrical signals to target cells
		Endocrine cells broadcast hormones
		Nervous systems and endocrine systems tend to control different processes
	Neurons Are Organized into Functional Circuits in Nervous Systems
	The Cellular Organization of Neural Tissue
		Neurons are structurally adapted to transmit action potentials
		Glial cells support neurons physically and metabolically
	The Ionic Basis of Membrane Potentials
		Cell membranes have passive electrical properties: Resistance and capacitance
		Resting membrane potentials depend on selective permeability to ions: The Nernst equation
		Ion concentration differences result from active ion transport and from passive diffusion
		Membrane potentials depend on the permeabilities to and concentration gradients of several ion species: The Goldman equation
		Electrogenic pumps also have a small direct effect on
	The Action Potential
		Action potentials are voltage-dependent, all-or-none electrical signals
		Action potentials result from changes in membrane permeabilities to ions
		The molecular structure of the voltagedependent ion channels reveals their functional properties
		There are variations in the ionic mechanisms of excitable cells
	The Propagation of Action Potentials
		Local circuits of current propagate an action potential
		Membrane refractory periods prevent bidirectional propagation
		The conduction velocity of an action potential depends on axon diameter, myelination, and temperature
	Study Questions
	References
PART III Integrating Systems
Chapter 13 Synapses
	Synaptic Transmission Is Usually Chemical but Can Be Electrical
		Electrical synapses transmit signals instantaneously
		Chemical synapses can modify and amplify signals
	Synaptic Potentials Control Neuronal Excitability
		Synapses onto a spinal motor neuron exemplify functions of fast synaptic potentials
		Synapses excite or inhibit a neuron by depolarization or hyperpolarization at the site of impulse initiation
	Fast Chemical Synaptic Actions Are Exemplified by the Vertebrate Neuromuscular Junction
		Chemical synapses work by releasing and responding to neurotransmitters
		Postsynaptic potentials result from permeability changes that are neurotransmitter-dependent and voltage-independent
		EPSPs between neurons resemble neuromuscular EPSPs but are smaller
		Fast IPSPs can result from an increase in permeability to chloride
	Presynaptic Neurons Release Neurotransmitter Molecules in Quantal Packets
		Acetylcholine is synthesized and stored in the presynaptic terminal
		Neurotransmitter release requires voltagedependent Ca2+ influx
		Neurotransmitter release is quantal and vesicular
		Synaptic vesicles are cycled at nerve terminals in distinct steps
		Several proteins play roles in vesicular release and recycling
	Neurotransmitters Are of Two General Kinds
		Neurons have one or more characteristic neurotransmitters
		An agent is identified as a neurotransmitter if it meets several criteria
		Vertebrate neurotransmitters have several general modes of action
		Neurotransmitter systems have been conserved in evolution
	Postsynaptic Receptors for Fast Ionotropic Actions: Ligand-Gated Channels
		ACh receptors are ligand-gated channels that function as ionotropic receptors
		Many, but not all, ligand-gated channel receptors have evolved from a common ancestor
	Postsynaptic Receptors for Slow, Metabotropic Actions: G Protein– Coupled Receptors
		G protein–coupled receptors initiate signal transduction cascades
		Metabotropic receptors act via second messengers
		Other mechanisms of G protein–mediated activity
		G protein–coupled receptors mediate permeability-decrease synaptic potentials and presynaptic inhibition
	Synaptic Plasticity: Synapses Change Properties with Time and Activity
		Neurotransmitter metabolism is regulated homeostatically
		Learning and memory may be based on synaptic plasticity
		Habituation and sensitization in
		Long-term potentiation in the hippocampus
		Long-term potentiation is a necessary component of learning
	Study Questions
	References
Chapter 14 Sensory Processes
	Organization of Sensory Systems
		Sensory receptor cells can be classified in four different ways
		Sensory receptor cells transduce and encode sensory information
	Mechanoreception and Touch
		Insect bristle sensilla exemplify mechanoreceptor responses
		Touch receptors in the skin of mammals have specialized endings
		Proprioceptors monitor internal mechanical stimuli
	Vestibular Organs and Hearing
		Insects hear with tympanal organs
		Vertebrate hair cells are used in hearing and vestibular sense
		Vertebrate vestibular organs sense acceleration and gravity
		Sound stimuli create movements in the vertebrate cochlea that excite auditory hair cells
		The localization of sound is determined by analysis of auditory signals in the CNS
	Chemoreception and Taste
		Insect taste is localized at chemoreceptive sensilla
		Taste in mammals is mediated by receptor cells in taste buds
	Olfaction
		The mammalian olfactory epithelium contains odor-generalist receptor cells
		The vomeronasal organ of mammals detects pheromones
	Photoreception
		Photoreceptor cells and eyes of different groups have evolved similarities and differences
		Rhodopsin consists of retinal conjugated to opsin, a G protein–coupled receptor
		Phototransduction in Drosophila leads to a depolarizing receptor potential
		The vertebrate eye focuses light onto retinal rods and cones
		Rods and cones of the retina transduce light into a hyperpolarizing receptor potential
		Enzymatic regeneration of rhodopsin is slow
	Visual Sensory Processing
		Retinal neurons respond to contrast
		The vertebrate brain integrates visual information through parallel pathways
		Color vision is accomplished by populations of photoreceptors that contain different photopigments
	Study Questions
	References
Chapter 15 Nervous System Organization and Biological Clocks
	The Organization and Evolution of Nervous Systems
		Nervous systems consist of neurons organized into functional circuits
		Many types of animals have evolved complex nervous systems
	The Vertebrate Nervous System: A Guide to the General Organizational Features of Nervous Systems
		Nervous systems have central and peripheral divisions
		The central nervous system controls physiology and behavior
		Five principles of functional organization apply to all mammalian and most vertebrate brains
		The peripheral nervous system has somatic and autonomic divisions that control different parts of the body
		The autonomic nervous system has three divisions
	Biological Clocks
		Organisms have endogenous rhythms
		Biological clocks generate endogenous rhythms
		Control by biological clocks has adaptive advantages
		Endogenous clocks correlate with natural history and compensate for temperature
		Clock mechanisms are based on rhythms of gene expression
		The loci of biological clock functions vary among animals
		Circannual and circatidal clocks: Some endogenous clocks time annual or tidal rhythms
		Interval, or “hourglass,” timers can time shorter intervals
	Study Questions
	References
Chapter 16 Endocrine and Neuroendocrine Physiology
	Introduction to Endocrine Principles
		Hormones bind to receptor molecules expressed by target cells
		Concentrations of hormones in the blood vary in response to varying conditions
		Most hormones fall into three chemical classes
		Hormone molecules exert their effects by producing biochemical changes in target cells
		Water-soluble carrier proteins in the blood transport lipid-soluble hormones and many water-soluble hormones
	Synthesis, Storage, and Release of Hormones
		Peptide hormones are synthesized at ribosomes, stored in vesicles, and secreted on demand
		Steroid hormones are synthesized on demand prior to secretion, and are released into the blood by diffusion
	Types of Endocrine Cells and Glands
	Control of Endocrine Secretion: The Vertebrate Pituitary Gland
		The posterior pituitary illustrates neural control of neurosecretory cells
		The anterior pituitary illustrates neurosecretory control of endocrine cells
		Hormones and neural input modulate endocrine control pathways
	The Mammalian Stress Response
		The autonomic nervous system and HPA axis coordinate the stress response to an acute threat
		The HPA axis modulates the immune system
		Chronic stress causes deleterious effects
		Plasma glucocorticoid concentrations show seasonal variations
	Endocrine Control of Nutrient Metabolism in Mammals
		Insulin regulates short-term changes in nutrient availability
		Glucagon works together with insulin to ensure stable levels of glucose in the blood
		Other hormones contribute to the regulation of nutrient metabolism
	Endocrine Control of Salt and Water Balance in Vertebrates
		Antidiuretic hormones conserve water
		The renin–angiotensin–aldosterone system conserves sodium and excretes potassium
		Atrial natriuretic peptide promotes excretion of sodium and water
	Endocrine Control of Calcium Metabolism in Mammals
		Parathyroid hormone increases Ca2+ in the blood
		Active vitamin D increases Ca2+ and phosphate in the blood
		Calcitonin opposes bone resorption and decreases Ca2+ and phosphate in the blood
	Endocrine Principles in Review
	Chemical Signals along a Distance Continuum
		Paracrines are local chemical signals distributed by diffusion
		Pheromones and kairomones are used as chemical signals between animals
	Insect Metamorphosis
		Insect metamorphosis may be gradual or dramatic
		Hormones and neurohormones control insect metamorphosis
	Study Questions
	References
Chapter 17 Reproduction
	The Two Worlds of Reproductive Physiology
	What Aspects of Reproduction Do Physiologists Study?
	The Environment as a Player in Reproduction
		Temperature and photoperiod are often used as cues
		Latitudinal trends graphically illustrate the importance of the environment
		Animals living in distinctive habitats often use distinctive cues for reproduction
	Reproduce Once or More Than Once?
	Eggs, Provisioning, and Parental Care
	External or Internal Fertilization?
	The Timing of Reproductive Cycles
		Sperm storage permits flexible timing between copulation and fertilization
		Embryonic diapause permits flexible timing between fertilization and the completion of embryonic development
		Embryonic diapause and other forms of diapause are common in insects
		Delayed implantation and postpartum estrus play important timing roles in mammals
		Some iteroparous animals reproduce only once a year
	Sex Change
	Reproductive Endocrinology of Placental Mammals
		Females ovulate periodically and exhibit menstrual or estrous cycles
		Males produce sperm continually during the reproductive season
		Pregnancy and birth are orchestrated by specialized endocrine controls
		Lactation, a costly part of reproduction, is governed by neuroendocrine reflexes
	Study Questions
	References
Chapter 18 Integrating Systems AT WORK: Animal Navigation
	The Adaptive Significance of Animal Navigation
		Navigational abilities promote reproductive success
		Navigational abilities facilitate food acquisition
		Migrating animals need navigation
	Navigational Strategies
		Trail following is the most rudimentary form of animal navigation
		Piloting animals follow a discontinuous series of learned cues
		Path integration is a form of dead reckoning
		Animals can derive compass information from environmental cues
		Some animals appear to possess a map sense
		Sea turtles exemplify the degree of our understanding of navigation
	Innate and Learned Components of Navigation
		Some forms of navigation have strong innate aspects
		The hippocampus is a critical brain area for vertebrate spatial learning and memory
	Study Questions
	References
PART IV Movement and Muscle
Chapter 19 Control of Movement: The Motor Bases of Animal Behavior
	Neural Control of Skeletal Muscle Is the Basis of Animal Behavior
		Invertebrate neural circuits involve fewer neurons than vertebrate circuits
		Vertebrate spinal reflexes compensate for circumstances, as well as initiate movements
		Motor neurons are activated primarily by CNS input rather than by spinal reflexes
	Neural Generation of Rhythmic Behavior
		Locust flight results from an interplay of CNS and peripheral control
		There are different mechanisms of central pattern generation
		Central pattern generators can underlie relatively complex behavior
	Control and Coordination of Vertebrate Movement
		Locomotion in cats involves spinal central pattern generators
		Central pattern generators are distributed and interacting
		The generation of movement involves several areas in the vertebrate brain
	Study Questions
	References
Chapter 20 Muscle
	Vertebrate Skeletal Muscle Cells
		Thick and thin filaments are polarized polymers of individual protein molecules
		Muscles require ATP to contract
		Calcium and the regulatory proteins tropomyosin and troponin control contractions
	Excitation–Contraction Coupling
	Whole Skeletal Muscles
		Muscle contraction is the force generated by a muscle during cross-bridge activity
		A twitch is the mechanical response of a muscle to a single stimulus
		The velocity of shortening decreases as the load increases
		A sustained high calcium concentration in the cytoplasm permits summation and tetanus
		The frequency of action potentials determines the tension developed by a muscle
		The amount of tension developed by a muscle depends on the length of the muscle at the time it is stimulated
		In general, the amount of work a muscle can do depends on its volume
	Muscle Energetics
		ATP is the immediate source of energy for powering muscle contraction
		Vertebrate muscle fibers vary in their use of ATP
		Different animals employ different types of muscles that contribute to their achieving success
	Neural Control of Skeletal Muscle
		The vertebrate plan is based on muscles organized into motor units
		The innervation of vertebrate tonic muscle is intermediate between the vertebrate and arthropod plans
		The arthropod plan employs multiterminal and polyneuronal innervation
	Vertebrate Smooth (Unstriated) Muscle
		Smooth muscle cells are broadly classified
		Ca2+ availability controls smooth muscle contraction by myosin-linked regulation
		The autonomic nervous system (ANS) innervates smooth muscles
	Vertebrate Cardiac Muscle
	Study Questions
	References
Chapter 21 Movement and Muscle AT WORK: Plasticity in Response to Use and Disuse
	Muscle Phenotypes
		Power output determines a muscle’s contractile performance, and changes in response to use and disuse
		Endurance training elicits changes in fiber type, increased capillary density, and increased mitochondrial density
		Resistance training causes hypertrophy and changes in fiber type
		Both resistance-trained and endurance-trained muscles continue to remodel during taper
		Combined resistance and endurance training can improve performance
		Hypertrophy also occurs in cardiac muscles
	Atrophy
		Humans experience atrophy in microgravity
		Disuse influences the fiber-type composition of muscles
		Muscles atrophy with age
		Some animals experience little or no disuse atrophy
	Regulating Muscle Mass
		Myostatin
		The PI3K–Akt1 pathway
	Summary
	Study Questions
	References
PART V Oxygen, Carbon Dioxide, and Internal Transport
Chapter 22 Introduction to Oxygen and Carbon Dioxide Physiology
	The Properties of Gases in Gas Mixtures and Aqueous Solutions
		Gases in the gas phase
		Gases in aqueous solution
	Diffusion of Gases
		Gases diffuse far more readily through gas phases than through aqueous solutions
		Gas molecules that combine chemically with other molecules cease to contribute to the gas partial pressure
	Convective Transport of Gases: Bulk Flow
		Gas transport in animals often occurs by alternating convection and diffusion
	The Oxygen Cascade
	Expressing the Amounts and Partial Pressures of Gases in Other Units
	The Contrasting Physical Properties of Air and Water
	Respiratory Environments
	Study Questions
	References
Chapter 23 External Respiration: The Physiology of Breathing
	Fundamental Concepts of External Respiration
	Principles of Gas Exchange by Active Ventilation
		The O2 partial pressure in blood leaving a breathing organ depends on the spatial relation between the flow of the blood and the
		Arterial CO2 partial pressures are much lower in water breathers than air breathers
	Low O2: Detection and Response
	Introduction to Vertebrate Breathing
	Breathing by Fish
		Gill ventilation is usually driven by buccal– opercular pumping
		Many fish use ram ventilation on occasion, and some use it all the time
		Decreased O2 and exercise are the major stimuli for increased ventilation in fish
		Several hundred species of bony fish are able to breathe air
	Breathing by Amphibians
		Gills, lungs, and skin are used in various combinations to achieve gas exchange
	Breathing by Reptiles Other than Birds
	Breathing by Mammals
		The total lung volume is employed in different ways in different sorts of breathing
		The gas in the final airways differs from atmospheric air in composition and is motionless
		The forces for ventilation are developed by the diaphragm and the intercostal and abdominal muscles
		The control of ventilation
		In species of different sizes, lung volume tends to be a constant proportion of body size, but breathing frequency varies allome
		Pulmonary surfactant keeps the alveoli from collapsing
	Breathing by Birds
		Ventilation is by bellows action
		Air flows unidirectionally through the parabronchi
		The gas-exchange system is cross-current
	Breathing by Aquatic Invertebrates and Allied Groups
		Molluscs exemplify an exceptional diversity of breathing organs built on a common plan
		Decapod crustaceans include many important water breathers and some air breathers
	Breathing by Insects and Other Tracheate Arthropods
		Diffusion is a key mechanism of gas transport through the tracheal system
		Some insects employ conspicuous ventilation
		Microscopic ventilation is far more common than believed even 15 years ago
		Control of breathing
		Aquatic insects breathe sometimes from the water, sometimes from the atmosphere, and sometimes from both
	Study Questions
	References
Chapter 24 Transport of Oxygen and Carbon Dioxide in Body Fluids (with an Introduction to Acid–Base Physiology)
	The Chemical Properties and Distributions of the Respiratory Pigments
		Hemoglobins contain heme and are the most widespread respiratory pigments
		Copper-based hemocyanins occur in many arthropods and molluscs
		Chlorocruorins resemble hemoglobins and occur in certain annelids
		Iron-based hemerythrins do not contain heme and occur in three or four phyla
	The O2-Binding Characteristics of Respiratory Pigments
		Human O2 transport provides an instructive case study
		A set of general principles helps elucidate O2 transport by respiratory pigments
		The shape of the oxygen equilibrium curve depends on O2-binding site cooperativity
		Respiratory pigments exhibit a wide range of affinities for O2
		The Bohr effect: Oxygen affinity depends on the partial pressure of CO2 and the pH
		The Root effect: In unusual cases, CO2 and pH dramatically affect the oxygen-carrying capacity of the respiratory pigment
		Thermal effects: Oxygen affinity depends on tissue temperature
		Organic modulators often exert chronic effects on oxygen affinity
		Inorganic ions may also act as modulators of respiratory pigments
	The Functions of Respiratory Pigments in Animals
		Patterns of circulatory O2 transport: The mammalian model is common but not universal
		Respiratory pigments within a single individual often display differences in O2 affinity that aid successful O2 transport
		Evolutionary adaptation: Respiratory pigments are molecules positioned directly at the interface between animal and environment
		The respiratory-pigment physiology of individuals undergoes acclimation and acclimatization
		Icefish live without hemoglobin
	Carbon Dioxide Transport
		The extent of bicarbonate formation depends on blood buffers
		Carbon dioxide transport is interpreted by use of carbon dioxide equilibrium curves
		The Haldane effect: The carbon dioxide equilibrium curve depends on blood oxygenation
		Critical details of vertebrate CO2 transport depend on carbonic anhydrase and anion transporters
	Acid–Base Physiology
		Acid–base regulation involves excretion or retention of chemical forms affecting H+ concentration
		Disturbances of acid–base regulation fall into respiratory and metabolic categories
	Study Questions
	References
Chapter 25 Circulation
	Hearts
		The heart as a pump: The action of a heart can be analyzed in terms of the physics of pumping
		The circulation must deliver O2 to the myocardium
		The electrical impulses for heart contraction may originate in muscle cells or neurons
		A heart produces an electrical signature, the electrocardiogram
		Heart action is modulated by hormonal, nervous, and intrinsic controls
	Principles of Pressure, Resistance, and Flow in Vascular Systems
		The rate of blood flow depends on differences in blood pressure and on vascular resistance
		The dissipation of energy: Pressure and flow turn to heat during circulation of the blood
	Circulation in Mammals and Birds
		The circulatory system is closed
		Each part of the systemic vascular system has distinctive anatomical and functional features
		Mammals and birds have a high-pressure systemic circuit
		Fluid undergoes complex patterns of exchange across the walls of systemic capillaries
		The pulmonary circuit is a comparatively lowpressure system that helps keep the lungs “dry”
		During exercise, blood flow is increased by orchestrated changes in cardiac output and vascular resistance
		Species have evolved differences in their circulatory physiology
		Vascular countercurrent exchangers play important physiological roles
	Circulation in Fish
		The circulatory plans of fish with air-breathing organs (As) pose unresolved questions
		Lungfish have specializations to promote separation of oxygenated and deoxygenated blood
	Circulation in Amphibians and in Reptiles Other than Birds
	Concluding Comments on Vertebrates
	Invertebrates with Closed Circulatory Systems
	Invertebrates with Open Circulatory Systems
		The crustacean circulatory system provides an example of an open system
		Open systems are functionally different from closed systems but may be equal in critical ways
	Study Questions
	References
Chapter 26 Oxygen, Carbon Dioxide, and Internal Transport AT WORK: Diving by Marine Mammals
	Diving Feats and Behavior
	Types of Dives and the Importance of Method
	Physiology: The Big Picture
	The Oxygen Stores of Divers
		The blood O2 store tends to be large in diving mammals
		Diving mammals have high myoglobin concentrations and large myoglobin-bound O2 stores
		Diving mammals vary in their use of the lungs as an O2 store
		Total O2 stores never permit dives of maximum duration to be fully aerobic
	Circulatory Adjustments during Dives
		Regional vasoconstriction: Much of a diving mammal’s body is cut off from blood flow during forced or protracted dives
		Diving bradycardia matches cardiac output to the circulatory task
		Cardiovascular responses are graded in freely diving animals
		Red blood cells are removed from the blood between dive sequences in some seals
	Metabolism during Dives
		The body becomes metabolically subdivided during forced or protracted dives
		Metabolic limits on dive duration are determined by O2 supplies, by rates of metabolic O2 use and lactic acid production, and by
	The Aerobic Dive Limit: One of Physiology’s Key Benchmarks for Understanding Diving Behavior
		Marine mammals exploit multiple means of reducing their metabolic costs while underwater
	Decompression Sickness
		Human decompression sickness is usually caused by N2 absorption from a compressed-air source
		Breath-hold dives must be repeated many times to cause decompression sickness in humans
		Marine mammals have been thought—perhaps erroneously—to avoid decompression sickness during deep dives by alveolar collapse
		Decompression sickness is an unresolved phenomenon
	A Possible Advantage for Pulmonary O2 Sequestration in Deep Dives
	Study Questions
	References
PART VI Water, Salts, and Excretion
Chapter 27 Water and Salt Physiology: Introduction and Mechanisms
	The Importance of Animal Body Fluids
	The Relationships among Body Fluids
	Types of Regulation and Conformity
	Natural Aquatic Environments
	Natural Terrestrial Environments
	Organs of Blood Regulation
		The osmotic U/P ratio is an index of the action of the kidneys in osmotic regulation
		The effects of kidney function on volume regulation depend on the amount of urine produced
		The effects of kidney function on ionic regulation depend on ionic U/P ratios
	Food and Drinking Water
		Salty drinking water may not provide H2O
		Plants and algae with salty tissue fluids pose challenges for herbivores
		Air-dried foods contain water
		Protein-rich foods can be dehydrating for terrestrial animals
	Metabolic Water
		Metabolic water matters most in animals that conserve water effectively
	Cell-Volume Regulation
	From Osmolytes to Compatible Solutes: Terms and Concepts
	Study Questions
	References
Chapter 28 Water and Salt Physiology of Animals in Their Environments
	Animals in Freshwater
		Passive water and ion exchanges: Freshwater animals tend to gain water by osmosis and lose major ions by diffusion
		Most types of freshwater animals share similar regulatory mechanisms
		A few types of freshwater animals exhibit exceptional patterns of regulation
		Why do most freshwater animals make dilute urine?
	Animals in the Ocean
		Most marine invertebrates are isosmotic to seawater
		Hagfish are the only vertebrates with blood inorganic ion concentrations that make them isosmotic to seawater
		The marine teleost fish are markedly hyposmotic to seawater
		Some arthropods of saline waters are hyposmotic regulators
		Marine reptiles (including birds) and mammals are also hyposmotic regulators
		Marine elasmobranch fish are hyperosmotic but hypoionic to seawater
	Animals That Face Changes in Salinity
		Migratory fish and other euryhaline fish are dramatic and scientifically important examples of hyper-hyposmotic regulators
		Genomic studies point to greater geneexpression changes in crustaceans than fish
		Animals undergo change in all time frames in their relations to ambient salinity
	Responses to Drying of the Habitat in Aquatic Animals
	Animals on Land: Fundamental Physiological Principles
		A low integumentary permeability to water is a key to reducing evaporative water loss on land
		Respiratory evaporative water loss depends on the function of the breathing organs and the rate of metabolism
		An animal’s total rate of evaporative water loss depends on its body size and phylogenetic group
		Excretory water loss depends on the concentrating ability of the excretory organs and the amount of solute that needs to be excr
		Terrestrial animals sometimes enter dormancy or tolerate wide departures from homeostasis to cope with water stress
		The total rates of water turnover of free-living terrestrial animals follow allometric patterns
	Animals on Land: Case Studies
		Amphibians occupy diverse habitats despite their meager physiological abilities to limit water losses
		Xeric invertebrates: Because of exquisite water conservation, some insects and arachnids have only small water needs
		Xeric vertebrates: Studies of lizards and small mammals help clarify the complexities of desert existence
		Xeric vertebrates: Some desert birds have specialized physiological properties
	Control of Water and Salt Balance in Terrestrial Animals
	Study Questions
	References
Chapter 29 Kidneys and Excretion (with Notes on Nitrogen Excretion)
	Basic Mechanisms of Kidney Function
		Primary urine is introduced into kidney tubules by ultrafiltration or secretion
		The predominant regulatory processes in kidney function: After primary urine forms, solutes and water are recovered from it for
	Urine Formation in Amphibians
		The proximal convoluted tubule reabsorbs much of the filtrate—returning it to the blood plasma—without changing the osmotic pres
		The distal convoluted tubule can differentially reabsorb water and solutes, thereby regulating the ratio of water to solutes in
		ADH exerts an elaborate pattern of control over nephron function
		The bladder functions in urine formation in amphibians
		The amphibian excretory system has mechanisms to promote excretion of urea
	Urine Formation in Mammals
		The nephrons, singly and collectively, give the mammalian kidney a distinctive structure
		Comparative anatomy points to a role for the loops of Henle in concentrating the urine
		Countercurrent multiplication is the key to producing concentrated urine
		The regulatory roles of the kidney tubules in overview: The concentrating and diluting kidney and the control of transitions
		Modern molecular and genomic methods create new frontiers in the study of kidney function
	Urine Formation in Other Vertebrates
		Freshwater and marine teleost fish differ in nephron structure and function
		The reptiles other than birds have nephrons like those of amphibians, but birds have some mammalian-type nephrons
	Urine Formation in Decapod Crustaceans
	Urine Formation in Molluscs
	Urine Formation in Insects
		The Malpighian tubules form and sometimes modify the primary urine
		The hindgut modulates urine volume and composition in regulatory ways
	Nitrogen Disposition and Excretion
		Ammonotelism is the primitive state
		Urea is more costly to synthesize but less toxic than ammonia
		Uric acid and related compounds remove nitrogen from solution
	Study Questions
	References
Chapter 30 Water, Salts, and Excretion AT WORK: Mammals of Deserts and Dry Savannas
	Desert and Dry-Savanna Environments
	The Relations of Animals to Water
		Large body size is a physiological advantage in terms of water costs
		Coexisting species are diverse in their relations to drinking water
		Water conflicts threaten animals and people
		All species of large herbivores require considerable amounts of preformed water
		Water and food resources in the deserts and dry savannas are often complex
	The Dramatic Adaptations of Particular Species
		Oryxes represent the pinnacle of desert survival
		Grant’s and Thomson’s gazelles differ in their relations to water
		The sand gazelle is drinking-water-independent in hyperarid deserts
		The dromedary camel does not store water, but conserves it and tolerates profound dehydration
	Study Questions
	References
APPENDICES
Appendix A The Système International and Other Units of Measure
Appendix B  Prefixes Indicating Orders of Magnitude
Appendix C Gases at Standard Temperature and Pressure
Appendix D Fitting Lines to Data
Appendix E Logarithms
Appendix F Exponential and Allometric Equations
Appendix G Phylogenetically Independent Contrasts
	References
Appendix H Mitosis and Meiosis
Appendix I The Standard Amino Acids
Appendix J Basic Physics Terms
	Mechanics
	Energy and related concepts
	Electricity and related concepts
Appendix K Summary of Major Bloodborne Hormones in Mammals
	References
Glossary
Photograph Credits
Figure and Table Citations
Additional References
Index
About the Book
Back Endpapers: A Simplified Phylogenetic Tree of the Animals and Descriptions of Major Phyla