Human Physiology From Cells to Systems (with CD-ROM and InfoTrac)

by Sherwood, Lauralee

• ISBN13: 9780534395018
• ISBN10: 0534395015
• Edition: 5th
• Format: Hardcover
• Copyright: 2003-06-02
• Publisher: Brooks Cole

Summary

Lauralee Sherwood's HUMAN PHYSIOLOGY is a market favorite, and in this new edition, technology takes the spotlight! Sherwood has worked hard to make the hallmark features of this title up-to-date, accurate and easy to use. Much of the anatomical and cellular art has been re-rendered. This new, three-dimensional art was conceived to support the great pedagogy instructors have come to expect. Accuracy has been maintained in a presentation that is clear, process-oriented and easy for students to understand. The central text theme of homeostasis has been retained by overwhelming reviewer demand. In support of this theme, Sherwood begins each chapter by showing how the system covered in that chapter supports homeostasis.

Table of Contents

Preface for the Students	xv
Homeostasis: The Foundation of Physiology	2	(20)
Introduction to Physiology	3	(1)
Physiology focuses on mechanisms of action
Structure and function are inseparable
Levels of Organization in the Body	4	(4)
The chemical level: Various atoms and molecules make up the body
The cellular level: Cells are the basic units of life
The tissue level: Tissues are groups of cells of similar specialization
The organ level: An organ is a unit made up of several tissue types
The body system level: A body system is a collection of related organs
Concepts, Challenges, and Controversies
Stem Cell Science and Tissue Engineering: The Quest to Make Defective Body Parts Like New Again	8	(2)
The organism level: The body systems are packaged together into a functional whole body
Concept of Homeostasis	10	(3)
Body cells are in contact with a privately maintained internal environment
Body systems maintain homeostasis, a dynamic steady state in the internal environment
A Closer Look at Exercise Physiology
What Is Exercise Physiology?	13	(3)
Homeostatic Control Systems	16	(3)
Homeostatic control systems may operate locally or bodywide
Negative feedback opposes an initial change and is widely used to maintain homeostasis
Positive feedback amplifies an initial change
Feedforward mechanisms initiate responses in anticipation of a change
Disruptions in homeostasis can lead to illness and death
Chapter in Perspective: Focus on Homeostasis	19	(1)
Chapter Summary	19	(1)
Review Exercises	20	(1)
Points to Ponder	20	(1)
PhysioEdge Resources	21	(1)
Cellular Physiology	22	(34)
Observations of Cells	23	(1)
Concepts, Challenges, and Controversies
HeLa Cells: Problems in a ``Growing'' Industry	24	(1)
An Overview of Cell Structure	24	(1)
The plasma membrane bounds the cell
The nucleus contains the DNA
The cytoplasm consists of various organelles and the cytosol
Endoplasmic Reticulum	25	(3)
The rough endoplasmic reticulum synthesizes proteins for secretion and membrane construction
The smooth endoplasmic reticulum packages new proteins in transport vesicles
Golgi Complex	28	(2)
Transport vesicles carry their cargo to the Golgi complex for further processing
The Golgi complex packages secretory vesicles for release by exocytosis
Lysosomes	30	(4)
Lysosomes serve as the intracellular digestive system
Extracellular material is brought into the cell by endocytosis for attack by lysosomal enzymes
Lysosomes remove useless but not useful parts of the cell
Peroxisomes	34	(1)
Peroxisomes house oxidative enzymes that detoxify various wastes
Mitochondria	34	(8)
Mitochondria, the energy organelles, are enclosed by a double membrane
Mitochondria play a major role in generating ATP
The cell generates more energy in aerobic than in anaerobic conditions
A Closer Look at Exercise Physiology
Aerobic Exercise: What For and How Much?	42	(1)
The energy stored in ATP is used for synthesis, transport, and mechanical work
Vaults	42	(1)
Vaults may serve as cellular transport vehicles
Cytosol	43	(1)
The cytosol is important in intermediary metabolism, ribosomal protein synthesis, and nutrient storage
Cytoskeleton	44	(8)
Microtubules help maintain asymmetrical cell shapes and play a role in complex cell movements
Microfilaments are important to cellular contractile systems and as mechanical stiffeners
Intermediate filaments are important in cell regions subject to mechanical stress
The cytoskeleton functions as an integrated whole and links other parts of the cell together
Chapter in Perspective: Focus on Homeostasis	51	(1)
Chapter Summary	52	(1)
Review Exercises	53	(1)
Points to Ponder	54	(1)
PhysioEdge Resources	55	(1)
The Plasma Membrane and Membrane Potential	56	(42)
Membrane Structure and Composition	58	(3)
The plasma membrane is a fluid lipid bilayer embedded with proteins
The lipid bilayer forms the basic structural barrier that encloses the cell
The membrane proteins perform a variety of specific membrane functions
Concepts, Challenges, and Controversies
Cystic Fibrosis: A Fatal Defect in Membrane Transport	61	(1)
The membrane carbohydrates serve as self-identity markers
Cell-to-Cell Adhesions	62	(3)
The extracellular matrix serves as the biological ``glue.''
Some cells are directly linked together by specialized cell junctions
Intercellular Communication and Signal Transduction	65	(5)
Communication between cells is largely orchestrated by extracellular chemical messengers
Extracellular chemical messengers bring about cell responses primarily by signal transduction
Some extracellular chemical messengers open chemically gated channels
Many extracellular chemical messengers activate second messenger pathways
Concepts, Challenges, and Controversies
Programmed Cell Suicide: A Surprising Example of a Signal Transduction Pathway	70	(1)
Overview of Membrane Transport	71	(1)
Unassisted Membrane Transport	72	(6)
Particles that can permeate the membrane passively diffuse down their concentration gradient
Ions that can permeate the membrane also passively move along their electrical gradient
Osmosis is the net diffusion of water down its own concentration gradient
Assisted Membrane Transport	78	(3)
Carrier-mediated transport is accomplished by a membrane carrier flipping its shape
Carrier-mediated transport may be passive or active
A Closer Look at Exercise Physiology
Exercising Muscles Have a ``Sweet Tooth''	81	(6)
With vesicular transport, material is moved into or out of the cell wrapped in membrane
Caveolae may play roles in membrane transport and signal transduction
Membrane Potential	87	(6)
Membrane potential refers to a separation of opposite charges across the membrane
Membrane potential is due to differences in the concentration and permeability of key ions
Chapter in Perspective: Focus on Homeostasis	92	(1)
Chapter Summary	93	(1)
Review Exercises	94	(2)
Points to Ponder	96	(1)
PhysioEdge Resources	97	(1)
Neuronal Physiology	98	(34)
Introduction	99	(1)
Nerve and muscle are excitable tissues
Membrane potential decreases during depolarization and increases during hyperpolarization
Electrical signals are produced by changes in ion movement across the plasma membrane
Graded Potentials	100	(3)
The stronger the triggering event, the larger the resultant graded potential
Graded potentials spread by passive current flow
Graded potentials die out over short distances
Action Potentials	103	(13)
During an action potential, the membrane potential rapidly, transiently reverses
Marked changes in membrane permeability and ion movement lead to an action potential
The Na+ -K+ pump gradually restores the concentration gradients disrupted by action potentials
Action potentials are propagated from the axon hillock to the axon terminals
Once initiated, action potentials are conducted throughout a nerve fiber
The refractory period ensures one-way propagation of the action potential
The refractory period also limits the frequency of action potentials
Action potentials occur in all-or-none fashion
The strength of a stimulus is coded by the frequency of action potentials
Myelination increases the speed of conduction of action potentials
Concepts, Challenges, and Controversies
Multiple Sclerosis: Myelin---Going, Going, Gone	116	(1)
Fiber diameter also influences the velocity of action potential propagation
Regeneration of Nerve Fibers	116	(1)
Schwann cells guide the regeneration of cut peripheral axons
Peripheral but not central nerve fibers can regenerate
Synapses and Neuronal Integration	117	(9)
Synapses are junctions between two neurons
A neurotransmitter carries the signal across a synapse
Some synapses excite whereas others inhibit the postsynaptic neuron
Each synapse is either always excitatory or always inhibitory
Neurotransmitters are quickly removed from the synaptic cleft
Some neurotransmitters function through intracellular second messenger systems
The grand postsynaptic potential depends on the sum of the activities of all presynaptic inputs
Action potentials are initiated at the axon hillock because it has the lowest threshold
Neuropeptides act primarily as neuromodulators
Presynaptic inhibition or facilitation can selectively alter the effectiveness of a presynaptic input
Drugs and diseases can modify synaptic transmission
Concepts, Challenges, and Controversies
Parkinson's Disease, Pollution, Ethical Problems, and Politics	126	(3)
Neurons are linked through complex converging and diverging pathways
Chapter in Perspective: Focus on Homeostasis	128	(1)
Chapter Summary	129	(1)
Review Exercises	130	(1)
Points to Ponder	131	(1)
PhysioEdge Resources	131	(1)
The Central Nervous System	132	(52)
Comparison of the Nervous and Endocrine Systems	133	(2)
The nervous system is a ``wired'' system, and the endocrine system is a ``wireless'' system
Neural specificity is due to anatomical proximity and endocrine specificity to receptor specialization
The nervous and endocrine systems have their own realms of authority but interact functionally
Organization of the Nervous System	135	(2)
The nervous system is organized into the central nervous system and the peripheral nervous system
The three classes of neurons are afferent neurons, efferent neurons, and interneurons
Protection and Nourishment of the Brain	137	(6)
Glial cells support the interneurons physically, metabolically, and functionally
The delicate central nervous system is well protected
Three meningeal membranes wrap, protect, and nourish the central nervous system
The brain floats in its own special cerebrospinal fluid
A highly selective blood-brain barrier carefully regulates exchanges between the blood and brain
Concepts, Challenges, and Controversies
Strokes: A Deadly Domino Effect	143	(1)
The brain depends on constant delivery of oxygen and glucose by the blood
Overview of the Central Nervous System	143	(2)
Cerebral Cortex	145	(9)
The cerebral cortex is an outer shell of gray matter covering an inner core of white matter
The cerebral cortex is organized into layers and functional columns
The four pairs of lobes in the cerebral cortex are specialized for different activities
The parietal lobes are rponsible for somatosensory processing
The primary motor cortex is located in the frontal lobes
Other brain regions besides the primary motor cortex are important in motor control
Somatotopic maps vary slightly between individuals and are dynamic, not static
Because of its plasticity, the brain can be remodeled in response to varying demands
Different aspects of language are controlled by different regions of the cortex
The association areas of the cortex are involved in many higher functions
The cerebral hemispheres have some degree of specialization
An electroencephalogram is a record of postsynaptic activity in cortical neurons
Neurons in different regions of the cerebral cortex may fire in rhythmic synchrony
Basal Nuclei, Thalamus, and Hypothalamus	154	(3)
The basal nuclei play an important inhibitory role in motor control
The thalamus is a sensory relay station and is important in motor control
The hypothalamus regulates many homeostatic functions
The Limbic System and Its Functional Relations with the Higher Cortex	157	(5)
The limbic system plays a key role in emotion
The limbic system and higher cortex participate in the control of basic behavior patterns
Motivated behaviors are goal directed
Norepinephrine, dopamine, and serotonin are neurotransmitters in pathways for emotions and behavior
Learning is the acquisition of knowledge as a result of experiences
Memory is laid down in stages
Memory traces are present in multiple regions of the brain
Concepts, Challenges, and Controversies
Alzheimer's Disease: A Tale of Beta Amyloid Plaques, Tau Tangles, and Dementia	162	(4)
Short-term memory involves transient changes in synaptic activity
Long-term memory involves formation of new, permanent synaptic connections
Cerebellum	166	(3)
The cerebellum is important in balance and in planning and execution of voluntary movement
Brain Stem	169	(3)
The brain stem is a vital link between the spinal cord and higher brain regions
Sleep is an active process consisting of alternating periods of slow-wave and paradoxical sleep
The sleep-wake cycle is controlled by interactions among three neural systems
The function of sleep is unclear
Spinal Cord	172	(5)
The spinal cord extends through the vertebral canal and is connected to the spinal nerves
The white matter of the spinal cord is organized into tracts
Each horn of the spinal cord gray matter houses a different type of neuronal cell body
Spinal nerves carry both afferent and efferent fibers
A Closer Look at Exercise Physiology
Swan Dive or Belly Flop: It's a Matter of CNS Control	177	(3)
The spinal cord is responsible for the integration of many basic reflexes
Chapter in Perspective: Focus on Homeostasis	180	(1)
Chapter Summary	180	(2)
Review Exercises	182	(1)
Points to Ponder	183	(1)
PhysioEdge Resources	183	(1)
The Peripheral Nervous System: Afferent Division; Special Senses	184	(52)
Introduction	185	(1)
Visceral afferents carry subconscious input while sensory afferents carry conscious input
Perception is the conscious awareness of surroundings derived from interpretation of sensory input
A Closer Look at Exercise Physiology
Back Swings and Prejump Crouches: What Do They Share in Common?	186	(1)
Receptor Physiology	186	(6)
Receptors have differential sensitivities to various stimuli
A stimulus alters the receptor's permeability, leading to a graded receptor potential
Receptor potentials may initiate action potentials in the afferent neuron
Receptors may adapt slowly or rapidly to sustained stimulation
Each somatosensory pathway is ``labeled'' according to modality and location
Acuity is influenced by receptive field size and lateral inhibition
Pain	192
Stimulation of nociceptors elicits the perception of pain plus motivational and emotional responses
The brain has a built-in analgesic system
Eye: Vision	184	(11)
Protective mechanisms help prevent eye injuries
Concepts, Challenges, and Controversies
Acupuncture: Is It for Real?	195	(18)
The eye is a fluid-filled sphere enclosed by three specialized tissue layers
The amount of light entering the eye is controlled by the iris
The eye refracts the entering light to focus the image on the retina
Accommodation increases the strength of the lens for near vision
Light must pass through several retinal layers before reaching the photoreceptors
Phototransduction by retinal cells converts light stimuli into neural signals
Rods provide indistinct gray vision at night whereas cones provide sharp color vision during the day
The sensitivity of the eyes can vary markedly through dark and light adaptation
Color vision depends on the ratios of stimulation of the three cone types
Visual information is modified and separated before reaching the visual cortex
The thalamus and visual cortexes elaborate the visual message
Visual input goes to other areas of the brain not involved in vision perception
Some sensory input may be detected by multiple sensory processing areas in the brain
Concepts, Challenges, and Controversies
``Seeing'' with the Tongue	213	(1)
Ear: Hearing and Equilibrium	213	(11)
Sound waves consist of alternate regions of compression and rarefaction of air molecules
The external ear plays a role in sound localization
The tympanic membrane vibrates in unison with sound waves in the external ear
The middle ear bones convert tympanic-membrane vibrations into fluid movements in the inner ear
The cochlea contains the organ of Corti, the sense organ for hearing
Hair cells in the organ of Corti transduce fluid movements into neural signals
Pitch discrimination depends on the region of the basilar membrane that vibrates
Loudness discrimination depends on the amplitude of the vibration
The auditory cortex is mapped according to tone
Deafness is caused by defects either in conduction or neural processing of sound waves
The vestibular apparatus is important for equilibrium by detecting position and motion of the head
Chemical Senses: Taste and Smell	224	(8)
Taste receptor cells are located primarily within tongue taste buds
Taste discrimination is coded by patterns of activity in various taste bud receptors
The olfactory receptors in the nose are specialized endings of renewable afferent neurons
Various parts of an odor are detected by different olfactory receptors and sorted into ``smell files.''
Odor discrimination is coded by patterns of activity in the olfactory bulb glomeruli
The olfactory system adapts quickly, and odorants are rapidly cleared
The vomeronasal organ detects pheromones
Chapter in Perspective: Focus on Homeostasis	232	(1)
Chapter Summary	232	(2)
Review Exercises	234	(1)
Points to Ponder	235	(1)
PhysioEdge Resources	235	(1)
The Peripheral Nervous System: Efferent Division	236	(20)
Introduction	237	(1)
Autonomic Nervous System	237
An autonomic nerve pathway consists of a two-neuron chain
Parasympathetic postganglionic fibers release acetylcholine; sympathetic ones release norepinephrine
The autonomic nervous system controls involuntary visceral organ activities
The sympathetic and parasympathetic systems dually innervate most visceral organs
The adrenal medulla is a modified part of the sympathetic nervous system
Several different receptor types are available for each autonomic neurotransmitter
Concepts, Challenges, and Controversies
The Autonomic Nervous System and Aging: A Fortuitous Find	224	(21)
Many regions of the central nervous system are involved in the control of autonomic activities
Somatic Nervous System	245	(1)
Motor neurons supply skeletal muscle
Motor neurons are the final common pathway
Neuromuscular Junction	246	(4)
Acetylcholine is the neuromuscular junction neurotransmitter
A Closer Look at Exercise Physiology
Loss of Muscle Mass: A Plight of Spaceflight	250	(2)
Acetylcholinesterase terminates acetylcholine activity at the neuromuscular junction
The neuromuscular junction is vulnerable to several chemical agents and diseases
Concepts, Challenges, and Controversies
Botulinum Toxin's Reputation Gets a Facelift	252	(1)
Chapter in Perspective: Focus on Homeostasis	253	(1)
Chapter Summary	253	(1)
Review Exercises	254	(1)
Points to Ponder	255	(1)
PhysioEdge Resources	255	(1)
Muscle Physiology	256	(46)
Introduction	257	(1)
Structure of Skeletal Muscle	258	(3)
Skeletal muscle fibers are striated due to a highly organized internal arrangement
Myosin forms the thick filaments
Actin is the main structural component of the thin filaments
Molecular Basis of Skeletal Muscle Contraction	261	(8)
During contraction, cycles of cross-bridge binding and bending pull the thin filaments inward
Calcium is the link between excitation and contraction
Contractile activity far outlasts the electrical activity that initiated it
Skeletal Muscle Mechanics	269	(8)
Whole muscles are groups of muscle fibers bundled together and attached to bones
Contractions of a whole muscle can be of varying strength
The number of fibers contracting within a muscle depends on the extent of motor unit recruitment
The frequency of stimulation can influence the tension developed by each muscle fiber
Twitch summation results from a sustained elevation in cytosolic calcium
There is an optimal muscle length at which maximal tension can be developed
Muscle tension is transmitted to bone as the contractile component tightens the series-elastic component
The two primary types of contraction are isotonic and isometric
The velocity of shortening is related to the load
Although muscles can accomplish work, much of the energy is converted to heat
Interactive units of skeletal muscles, bones, and joints form lever systems
Skeletal Muscle Metabolism and Fiber Types	277	(5)
Muscle fibers have alternate pathways for forming ATP
Fatigue may be of muscle or central origin
Increased oxygen consumption is necessary to recover from exercise
There are three types of skeletal muscle fibers based on differences in ATP hydrolysis and synthesis
Muscle fibers adapt considerably in response to the demands placed on them
A Closer Look at Exercise Physiology
Are Athletes Who Use Steroids to Gain
Competitive Advantage Really Winners or Losers?	282	(1)
Control of Motor Movement	283	(1)
Multiple neural inputs influence motor neuron output
Concepts, Challenges, and Controversies
Muscular Dystrophy: When One Small Step is a Big Deal	284	(4)
Muscle receptors provide afferent information needed to control skeletal muscle activity
Smooth and Cardiac Muscle	288	(9)
Smooth muscle cells are small and unstriated
Smooth muscle cells are turned on by Ca2+-dependent phosphorylation of myosin
Multiunit smooth muscle is neurogenic
Single-unit smooth muscle cells form functional syncytia
Single-unit smooth muscle is myogenic
Gradation of single-unit smooth muscle contraction differs from that of skeletal muscle
Smooth muscle can still develop tension yet inherently relaxes when stretched
Smooth muscle is slow and economical
Cardiac muscle blends features of both skeletal and smooth muscle
Chapter in Perspective: Focus on Homeostasis	297	(1)
Chapter Summary	297	(2)
Review Exercises	299	(2)
Points to Ponder	301	(1)
PhysioEdge Resources	301	(1)
Cardiac Physiology	302	(40)
Introduction	303	(1)
Anatomy of the Heart	304	(6)
The heart is a dual pump
Heart valves ensure that the blood flows in the proper direction through the heart
The heart walls are composed primarily of spirally arranged cardiac muscle fibers
Cardiac muscle fibers are interconnected by intercalated discs and form functional syncytia
The heart is enclosed by the pericardial sac
Electrical Activity of the Heart	310	(10)
Cardiac autorhythmic cells display pacemaker activity
The sinoatrial node is the normal pacemaker of the heart
The spread of cardiac excitation is coordinated to ensure efficient pumping
The action potential of cardiac contractile cells shows a characteristic plateau
Ca2+ entry from the ECF induces a much larger Ca2+ release from the sarcoplasmic reticulum
Tetanus of cardiac muscle is prevented by a long refractory period
The ECG is a record of the overall spread of electrical activity through the heart
Various components of the ECG record can be correlated to specific cardiac events
The ECG can be used to diagnose abnormal heart rates, arrhythmias, and damage of heart muscle
Mechanical Events of the Cardiac Cycle	320	(1)
The heart alternately contracts to empty and relaxes to fill
A Closer Look at Exercise Physiology
The What, Who, and When of Stress Testing	321	(4)
The two heart sounds are associated with valve closures
Turbulent blood flow produces heart murmurs
Cardiac Output and Its Control	325	(7)
Cardiac output depends on the heart rate and the stroke volume
Heart rate is determined primarily by autonomic influences on the SA node
Stroke volume is determined by the extent of venous return and by sympathetic activity
Increased end-diastolic volume results in increased stroke volume
The contractility of the heart is increased by sympathetic stimulation
High blood pressure increases the workload of the heart
The contractility of the heart is decreased in heart failure
Nourishing the Heart Muscle	332	(4)
The heart receives most of its own blood supply through the coronary circulation during diastole
Atherosclerotic coronary artery disease can deprive the heart of essential oxygen
Concepts, Challenges, and Controversies
Atherosclerosis: Cholesterol and Beyond	336	(2)
Chapter in Perspective: Focus on Homeostasis	338	(1)
Chapter Summary	338	(1)
Review Exercises	339	(2)
Points to Ponder	341	(1)
PhysioEdge Resources	341	(1)
The Blood Vessels and Blood Pressure	342	(48)
Introduction	343	(4)
To maintain homeostasis, reconditioning organs receive blood flow in excess of their own needs
Blood flow through vessels depends on the pressure gradient and vascular resistance
The vascular tree consists of arteries, arterioles, capillaries, venules, and veins
Concepts, Challenges, and Controversies
From Humors to Harvey: Historical Highlights in Circulation	347	(1)
Arteries	347	(4)
Arteries serve as rapid-transit passageways to the tissues and as a pressure reservoir
Arterial pressure fluctuates in relation to ventricular systole and diastole
Blood pressure can be measured indirectly by using a sphygmomanometer
Mean arterial pressure is the main driving force for blood flow
Arterioles	351	(9)
Arterioles are the major resistance vessels
Local control of arteriolar radius is important in determining the distribution of cardiac output
Local metabolic influences on arteriolar radius help match blood flow with the tissues' needs
Local histamine release pathologically dilates arterioles
Local physical influences on arteriolar radius include temperature changes and stretch
Extrinsic sympathetic control of arteriolar radius is important in the regulation of blood pressure
The medullary cardiovascular control center and several hormones regulate blood pressure
Capillaries	360	(10)
Capillaries are ideally suited to serve as sites of exchange
Water-filled capillary pores permit passage of small, water-soluble substances
Many capillaries are not open under resting conditions
Interstitial fluid is a passive intermediary between the blood and cells
Diffusion across the capillary walls is important in solute exchange
Bulk flow across the capillary walls is important in extracellular fluid distribution
The lymphatic system is an accessory route by which interstitial fluid can be returned to the blood
Edema occurs when too much interstitial fluid accumulates
Veins	370	(5)
Veins serve as a blood reservoir as well as passageways back to the heart
Venous return is enhanced by a number of extrinsic factors
Blood Pressure	375	(7)
Blood pressure is regulated by controlling cardiac output, total peripheral resistance, and blood volume
The baroreceptor reflex is an important short-term mechanism for regulating blood pressure
Other reflexes and responses influence blood pressure
Hypertension is a serious national public health problem, but its causes are largely unknown
A Closer Look at Exercise Physiology
The Ups and Downs of Hypertension and Exercise	382	(4)
Orthostatic hypotension results from transient inadequate sympathetic activity
Circulatory shock can become irreversible
Chapter in Perspective: Focus on Homeostasis	385	(1)
Chapter Summary	386	(1)
Review Exercises	387	(1)
Points to Ponder	388	(1)
PhysioEdge Resources	389	(1)
The Blood	390	(22)
Introduction	391	(1)
Plasma	391	(5)
Plasma water is a transport medium for many inorganic and organic substances
Many of the functions of plasma are carried out by plasma proteins
Erythrocytes
The structure of erythrocytes is well suited to their main function of O2 transport in the blood
The bone marrow continuously replaces worn-out erythrocytes
Erythropoiesis is controlled by erythropoietin from the kidneys
A Closer Look at Exercise Physiology
Blood Doping: Is more of a Good Thing Better?	396	(2)
Anemia can be caused by a variety of disorders
Polycythemia is an excess of circulating erythrocytes
Concepts, Challenges, and Controversies
In Search of a Blood Substitute	398	(1)
Leukocytes	398	(4)
Leukocytes primarily function as defense agents outside the blood
There are five types of leukocytes
Leukocytes are produced at varying rates depending on the changing defense needs of the body
Platelets and Hemostasis	402	(7)
Platelets are cell fragments derived from megakaryocytes
Hemostasis prevents blood loss from damaged small vessels
Vascular spasm reduces blood flow through an injured vessel
Platelets aggregate to from a plug at a vessel defect
Clot formation results from a triggered chain reaction involving plasma clotting factors
Fibrinolytic plasmin dissolves clots
Inappropriate clotting is responsible for thromboembolism
Hemophilia is the primary condition responsible for excessive bleeding
Chapter in Perspective: Focus on Homeostasis	408	(1)
Chapter Summary	409	(1)
Review Exercises	409	(1)
Points to Ponder	410	(1)
PhysioEdge Resources	411	(1)
The Body Defenses	412	(46)
Introduction	413	(3)
Pathogenic bacteria and viruses are the major targets of the immune system
Leukocytes are the effector cells of the immune system
Immune responses may be either innate and nonspecific or adaptive and specific
Innate Immunity	416	(8)
Inflammation is a nonspecific response to foreign invasion or tissue damage
Salicylates and glucocorticoid drugs suppress the inflammatory response
Interferon transiently inhibits multiplication of viruses in most cells
Natural killer cells destroy virus-infected cells and cancer cells upon first exposure to them
The complement system punches holes in micro-organisms
Adaptive Immunity: General Concepts	424	(1)
Adaptive immune responses include antibody-mediated immunity and cell-mediated immunity
An antigen induces an immune response against itself
B Lymphocytes: Antibody-Mediated Immunity	425	(5)
Antigens stimulate B cells to convert into plasma cells that produce antibodies
Antibodies are Y-shaped and classified according to properties of their tail portion
Antibodies largely amplify innate immune responses to promote antigen destruction
Clonal selection accounts for the specificity of antibody production
Selected clones differentiate into active plasma cells and dormant memory cells
Concepts, Challenges, and Controversies
Vaccination: A Victory Over Many Dreaded Diseases	430	(5)
The huge repertoire of B cells is built by reshuffling a small set of gene fragments
Active immunity is self-generated; passive immunity is ``borrowed.''
Blood types are a form of natural immunity
Lymphocytes respond only to antigen presented to them by antigen-presenting cells
T Lymphocytes: Cell-Mediated Immunity	435	(11)
T cells bind directly with their targets
The two types of T cells are cytotoxic T cells and helper T cells
Cytotoxic T cells secrete chemicals that destroy target cells
Helper T cells secrete chemicals that amplify the activity of other immune cells
The immune system is normally tolerant of self-antigens
Autoimmune diseases arise from loss of tolerance to self-antigens
The major histocompatibility complex is the code for self-antigens
Immune surveillance against cancer cells involves an interplay among immune cells and interferon
A regulatory loop links the immune system with the nervous and endocrine systems
A Closer Look at Exercise Physiology
Exercise: A Help or Hindrance to Immune Defense	446	(1)
Immune Diseases	446	(3)
Immune deficiency diseases result from insufficient immune responses
Allergies are inappropriate immune attacks against harmless environmental substances
External Defenses	449	(4)
The skin consists of an outer protective epidermis and an inner, connective tissue dermis
Specialized cells in the epidermis produce keratin and melanin and participate in immune defense
Protective measures within body cavities discourage pathogen invasion into the body
Chapter in Perspective: Focus on Homeostasis	452	(1)
Chapter Summary	453	(2)
Review Exercises	455	(1)
Points to Ponder	456	(1)
PhysioEdge Resources	457	(1)
The Respiratory System	458	(52)
Introduction	459	(4)
The respiratory airways conduct air between the atmosphere and alveoli
The gas-exchanging alveoli are thin-walled, inflatable sacs encircled by pulmonary capillaries
The lungs occupy much of the thoracic cavity
A pleural sac separates each lung from the thoracic wall
Respiratory Mechanics	463	(20)
Interrelationships among pressures inside and outside the lungs are important in ventilation
The lungs are normally stretched to fill the larger thorax
Flow of air into and out of the lungs occurs because of cyclical changes in intra-alveolar pressure
Airway resistance influences airflow rates
Airway resistance is abnormally increased with chronic obstructive pulmonary disease
Elastic behavior of the lungs is due to elastic connective tissue and alveolar surface tension
Pulmonary surfactant decreases surface tension and contributes to lung stability
The work of breathing normally requires only about 3% of total energy expenditure
The lungs normally operate at about ``half full.''
Alveolar ventilation is less than pulmonary ventilation because of the presence of dead space
Local controls act on the smooth muscle of the airways and arterioles to match airflow to blood flow
Gas Exchange	483	(5)
Gases move down partial pressure gradients
Oxygen enters and CO2 leaves the blood in the lungs passively down partial pressure gradients
Factors other than the partial pressure gradient influence the rate of gas transfer
Gas exchange across the systemic capillaries also occurs down partial pressure gradients
Gas Transport	488	(7)
Most O2 in the blood is transported bound to hemoglobin
The PO2 is the primary factor determining the percent hemoglobin saturation
Hemoglobin promotes the net transfer of O2 at both the alveolar and tissue levels
Factors at the tissue level promote the unloading of O2 from hemoglobin
Hemoglobin has a much higher affinity for carbon monoxide than for O2
Most CO2 is transported in the blood as bicarbonate
Various respiratory states are characterized by abnormal blood gas levels
Control of Respiration	495	(1)
Respiratory centers in the brain stem establish a rhythmic breathing pattern
Concepts, Challenges, and Controversies
Effects of Heights and Depths on the Body	496	(8)
The magnitude of ventilation is adjusted in response to three chemical factors: PO2, PCO2, and H+
Decreased arterial PO2 increases ventilation only as an emergency mechanism
Carbon dioxide-generated H+ in the brain is normally the primary regulator of ventilation
Adjustments in ventilation in response to changes in arterial H+ are important in acid--base balance
Exercise profoundly increases ventilation, but the mechanisms involved are unclear
Ventilation can be influenced by factors unrelated to the need for gas exchange
A Closer Look at Exercise Physiology
How to Find Out How Much Work You're Capable of Doing	504	(1)
During apnea, a person ``forgets to breathe''; during dyspnea, a person feels ``short of breath.''
Chapter in Perspective: Focus on Homeostasis	505	(1)
Chapter Summary	505	(2)
Review Exercises	507	(1)
Points to Ponder	508	(1)
PhysioEdge Resources	509	(1)
The Urinary System	510	(48)
Introduction	511	(6)
The kidneys perform a variety of functions aimed at maintaining homeostasis
The kidneys form the urine; the remainder of the urinary system carries the urine to the outside
The nephron is the functional unit of the kidney
The three basic renal processes are glomerular filtration, tubular reabsorption, and tubular secretion
Glomerular Filtration	517	(8)
The glomerular membrane is considerably more permeable than capillaries elsewhere
The glomerular capillary blood pressure is the major force that induces glomerular filtration
Changes in the GFR occur primarily as a result of changes in glomerular capillary blood pressure
The GFR can be influenced by changes in the filtration coefficient
The kidneys normally receive 20% to 25% of the cardiac output
Tubular Reabsorption	525	(9)
Tubular reabsorption is tremendous, highly selective, and variable
Tubular reabsorption involves transepithelial transport
An active Na+ -K+ ATPase pump in the basolateral membrane is essential for Na+ reabsorption
Aldosterone stimulates Na+ reabsorption in the distal and collecting tubules
Atrial natriuretic peptide inhibits Na+ reabsorption
Glucose and amino acids are reabsorbed by Na+ -dependent secondary active transport
In general, actively reabsorbed substances exhibit a tubular maximum
Glucose is an example of an actively reabsorbed substance that is not regulated by the kidneys
Phosphate is an example of an actively reabsorbed substance that is regulated by the kidneys
Active Na+ reabsorption is responsible for the passive reabsorption of Cl-, H2O, and urea
In general, unwanted waste products are not reabsorbed
Tubular Secretion	534	(3)
Hydrogen ion secretion is important in acid-base balance
Potassium secretion is controlled by aldosterone
Organic anion and cation secretion helps efficiently eliminate foreign compounds from the body
Urine Excretion and Plasma Clearance	537	(13)
Plasma clearance refers to the volume of plasma cleared of a particular substance per minute
The kidneys can excrete urine of varying concentrations depending on the body's state of hydration
The medullary vertical osmotic gradient is established by means of countercurrent multiplication
Vasopressin-controlled, variable H2O reabsorption occurs in the final tubular segments
Countercurrent exchange within the vasa recta conserves the medullary vertical osmotic gradient
Water and solute reabsorption versus excretion are only partially coupled
Renal failure has wide-ranging consequences
A Closer Look at Exercise Physiology
When Protein in the Urine Does Not Mean Kidney Disease	550	(1)
Urine is temporarily stored in the bladder, from which it is emptied by micturition
Concepts, Challenges, and Controversies
Dialysis: Cellophane Tubing or Abdominal Lining as an Artificial Kidney	551	(2)
Chapter in Perspective: Focus on Homeostasis	552	(1)
Chapter Summary	553	(2)
Review Exercises	555	(1)
Points to Ponder	556	(1)
PhysioEdge Resources	557	(1)
Fluid and Acid---Base Balance	558	(32)
Balance Concept	559	(1)
The internal pool of a substance is the amount of that substance in the ECF
To maintain stable balance of an ECF constituent, its input must equal its output
Fluid Balance	560	(6)
Body water is distributed between the ICF and ECF compartments
The plasma and interstitial fluid are similar in composition but the ECF and ICF differ markedly
Fluid balance is maintained by regulating ECF volume and osmolarity
Control of ECF volume is important in the long-term regulation of blood pressure
Control of salt balance is primarily important in regulating ECF volume
The amount of Na+ filtered is controlled through regulation of the GFR
The amount of Na+ reabsorbed is controlled through the renin-angiotensin-aldosterone system
Control of ECF osmolarity prevents changes in ICF volume
A Closer Look at Exercise Physiology
A Potentially Fatal Clash: When Exercising Muscles and Cooling
Mechanisms Compete for an Inadequate Plasma Volume	566	(5)
During ECF hypertonicity, the cells shrink as H2O leaves them
During ECF hypotonicity, the cells swell as H2O enters them
No water moves into or out of the cells during an ECF isotonic fluid gain or loss
Control of water balance by means of vasopressin is important in regulating ECF osmolarity
Vasopressin secretion and thirst are largely triggered simultaneously
Acid-Base Balance	571	(16)
Acids liberate free hydrogen ions, whereas bases accept them
The pH designation is used to express [H+]
Fluctuations in [H+] alter nerve, enzyme, and K+ activity
Hydrogen ions are continually added to the body fluids as a result of metabolic activities
Chemical buffer systems minimize changes in pH by binding with or yielding free H+
The H2CO3:HCO3- buffer pair is the primary ECF buffer for non-carbonic acids
The protein buffer system is primarily important intracellularly
The hemoglobin buffer system buffers H+ generated from carbonic acid
The phosphate buffer system is an important urinary buffer
Chemical buffer systems act as the first line of defense against changes in [H+]
The respiratory system regulates [H+] by controlling the rate of CO2 removal
The respiratory system serves as the second line of defense against changes in [H+]
The kidneys are a powerful third line of defense against changes in [H+]
The kidneys adjust their rate of H+ excretion depending on the plasma [H+] or [CO2]
The kidneys conserve or excrete HCO3- depending on the plasma [H+]
The kidneys secrete ammonia during acidosis to buffer secreted H+
Acid-base imbalances can arise from either respiratory dysfunction or metabolic disturbances
Respiratory acidosis arises from an increase in [CO2]
Respiratory alkalosis arises from a decrease in [CO2]
Metabolic acidosis is associated with a fall in [HCO3- ]
Metabolic alkalosis is associated with an elevation in [HCO3- ]
Chapter in Perspective: Focus on Homeostasis	586	(1)
Chapter Summary	587	(1)
Review Exercises	588	(1)
Points to Ponder	589	(1)
PhysioEdge Resources	589	(1)
The Digestive System	590	(56)
Introduction	561	(38)
The digestive system performs four basic digestive processes
The digestive tract and accessory digestive organs make up the digestive system
The digestive tract wall has four layers
Regulation of digestive function is complex and synergistic
Receptor activation alters digestive activity through neural reflexes and hormonal pathways
Mouth	599	(2)
The oral cavity is the entrance to the digestive tract
The teeth are responsible for chewing
Saliva begins carbohydrate digestion, is important in oral hygiene, and facilitates speech
Salivary secretion is continuous and can be reflexly increased
Digestion in the mouth is minimal; no absorption of nutrients occurs
Pharynx and Esophagus	601	(3)
Swallowing is a sequentially programmed all-or-none reflex
During the oropharyngeal stage of swallowing, food is prevented from entering the wrong passageways
The pharyngoesophageal sphincter prevents air from entering the digestive tract during breathing
Peristaltic waves push food through the esophagus
The gastroesophageal sphincter prevents reflux of gastric contents
Esophageal secretion is entirely protective
Stomach	604	(3)
The stomach stores food and begins protein digestion
Gastric filling involves receptive relaxation
Gastric storage takes place in the body of the stomach
Gastric mixing takes place in the antrum of the stomach
Gastric emptying is largely controlled by factors in the duodenum
A Closer Look at Exercise Physiology
Pregame Meal: What's In and What's Out?	607	(8)
Emotions can influence gastric motility
The stomach does not actively participate in vomiting
Gastric digestive juice is secreted by glands located at the base of gastric pits
Hydrochloric acid activates pepsinogen
Pepsinogen, once activated, begins protein digestion
Mucus is protective
Intrinsic factor is essential for absorption of vitamin B12
Multiple regulatory pathways influence the parietal and chief cells
Control of gastric secretion involves three phases
Gastric secretion gradually decreases as food empties from the stomach into the intestine
The stomach lining is protected from gastric secretions by the gastric mucosal barrier
Carbohydrate digestion continues in the body of the stomach; protein digestion begins in the antrum
The stomach absorbs alcohol and aspirin but no food
Concepts, Challenges, and Controversies
Ulcers: When Bugs Break the Barrier	615	(1)
Pancreatic and Biliary Secretions	615	(8)
The pancreas is a mixture of exocrine and endocrine tissue
The exocrine pancreas secretes digestive enzymes and an aqueous alkaline fluid
Pancreatic exocrine secretion is regulated by secretin and CCK
The liver performs various important functions including bile production
The liver lobules are delineated by vascular and bile channels
Bile is continuously secreted by the liver and is diverted to the gallbladder between meals
Bile salts are recycled through the enterohepatic circulation
Bile salts aid fat digestion and absorption
Bilirubin is a waste product excreted in the bile
Bile salts are the most potent stimulus for increased bile secretion
The gallbladder stores and concentrates bile between meals and empties during meals
Hepatitis and cirrhosis are the most common liver disorders
Small Intestine	623	(13)
Segmentation contractions mix and slowly propel the chyme
The migrating motility complex sweeps the intestine clean between meals
The ileocecal juncture prevents contamination of the small intestine by colonic bacteria
Small intestine secretions do not contain any digestive enzymes
The small intestine enzymes complete digestion intracellularly
The small intestine is remarkably well adapted for its primary role in absorption
The mucosal lining experiences rapid turnover
Energy-dependent Na+ absorption drives passive H2O absorption
Carbohydrate and protein are both absorbed by secondary active transport and enter the blood
Digested fat is absorbed passively and enters the lymph
Vitamin absorption is largely passive
Iron and calcium absorption is regulated
Most absorbed nutrients immediately pass through the liver for processing
Extensive absorption by the small intestine keeps pace with secretion
Biochemical balance among the stomach, pancreas, and small intestine is normally maintained
Diarrhea results in loss of fluid and electrolytes
Concepts, Challenges, and Controversies
Oral Rehydration Therapy: Sipping a Simple Solution Saves Lives	636	(1)
Large Intestine	637	(2)
The large intestine is primarily a drying and storage organ
Haustral contractions slowly shuffle the colonic contents back and forth
Mass movements propel colonic contents long distances
Feces are eliminated by the defecation reflex
Constipation occurs when the feces become too dry
Large intestine secretion is entirely protective
The colon contains myriad beneficial bacteria
The large intestine absorbs salt and water, converting the luminal contents into feces
Intestinal gases are absorbed or expelled
Overview of the Gastrointestinal Hormones	639	(2)
Chapter in Perspective: Focus on Homeostasis	641	(1)
Chapter Summary	641	(2)
Review Exercises	643	(1)
Points to Ponder	644	(1)
PhysioEdge Resources	645	(1)
Energy Balance and Temperature Regulation	646	(20)
Energy Balance	647	(7)
Most food energy is ultimately converted into heat in the body
The metabolic rate is the rate of energy use
Energy input must equal energy output to maintain a neutral energy balance
Food intake is controlled primarily by the hypothalamus
Obesity occurs when more kilocalories are consumed than are burned up
Persons suffering from anorexia nervosa have a pathologic fear of gaining weight
A Closer Look at Exercise Physiology
What the Scales Don't Tell You	654	(1)
Temperature Regulation	654	(8)
Internal core temperature is homeostatically maintained at 100°F
Heat input must balance heat output to maintain a stable core temperature
Heat exchange takes place by radiation, conduction, convection, and evaporation
The hypothalamus integrates a multitude of thermosensory inputs
Shivering is the primary involuntary means of increasing heat production
The magnitude of heat loss can be adjusted by varying the flow of blood through the skin
The hypothalamus simultaneously coordinates heat-production and heat-loss mechanisms
During a fever, the hypothalamic thermostat is ``reset'' at an elevated temperature
Hyperthermia can occur unrelated to infection
Concepts, Challenges, and Controversies
The Extremes of Heat and Cold Can Be Fatal	662	(1)
Chapter in Perspective: Focus on Homeostasis	663	(1)
Chapter Summary	663	(1)
Review Exercises	664	(1)
Points to Ponder	665	(1)
PhysioEdge Resources	665	(1)
Principles of Endocrinology; The Central Endocrine Glands	666	(34)
General Principles of Endocrinology	667	(14)
Hormones exert a variety of regulatory effects throughout the body
Hormones are chemically classified into three categories: peptides, amines, and steroids
The mechanisms of hormone synthesis, storage, and secretion vary according to the class of hormone
Water-soluble hormones dissolve in the plasma; lipid-soluble hormones are transported by plasma proteins
Hormones generally produce their effect by altering intracellular proteins
Hydrophilic hormones alter pre-existing proteins via second-messenger systems
By stimulating genes, lipophilic hormones promote synthesis of new proteins
Hormone actions are greatly amplified at the target cell
The effective plasma concentration of a hormone is normally regulated by changes in its rate of secretion
The effective plasma concentration of a hormone is influenced by its transport, metabolism, and excretion
Endocrine disorders result from hormone excess or deficiency or decreased target-cell responsiveness
The responsiveness of a target-cell can be varied by regulating the number of hormone-specific receptors
Pineal Gland and Circadian Rhythms	681	(1)
The suprachiasmatic nucleus is the master biological clock
Melatonin helps keep the body's circadian rhythms in time with the light-dark cycle
Concepts, Challenges, and Controversies
Tinkering with Our Biological Clocks	682	(1)
Hypothalamus and Pituitary	683	(2)
The pituitary gland consists of anterior and posterior lobes
The hypothalamus and posterior pituitary act as a unit to seete vasopressin and oxytocin
A Closer Look at Exercise Physiology
The Endocrine Response to the Challenge of Combined Heat and Marching Feet	685	(4)
The anterior pituitary secretes six established hormones, many of which are tropic
Hypothalamic releasing and inhibiting hormones help regulate anterior-pituitary hormone secretion
Target-gland hormones inhibit hypothalamic and anterior pituitary hormone secretion via negative feedback
Endocrine Control of Growth	689	(7)
Growth depends on growth hormone but is influenced by other factors as well
Growth hormone is essential for growth, but it also exerts metabolic effects not related to growth
Bone grows in thickness and in length by different mechanisms, both stimulated by growth hormone
Growth hormone exerts its growth-promoting effects indirectly by stimulating somatomedins
Growth hormone secretion is regulated by two hypophysiotropic hormones
Abnormal growth hormone secretion results in aberrant growth patterns
Other hormones besides growth hormone are essential for normal growth
Concepts, Challenges, and Controversies
Growth and Youth in a Bottle?	696	(1)
Chapter in Perspective: Focus on Homeostasis	697	(1)
Chapter Summary	697	(1)
Review Exercises	698	(1)
Points to Ponder	699	(1)
PhysioEdge Resources	699	(1)
The Peripheral Endocrine Glands	700	(48)
Thyroid Gland	701	(6)
The major cells that secrete thyroid hormone are organized into colloid-filled follicles
Thyroid hormone synthesis and storage occur on the thyroglobulin molecule
To secrete thyroid hormone, the follicular cells phagocytize thyroglobulin-laden colloid
Most of the secreted T4 is converted into T3 outside the thyroid
Thyroid hormone is the main determinant of the basal metabolic rate and exerts other effects as well
Thyroid hormone is regulated by the hypothalamus-pituitary-thyroid axis
Abnormalities of thyroid function include both hypothyroidism and hyperthyroidism
A goiter develops when the thyroid gland is overstimulated
Adrenal Glands	707	(12)
Each adrenal gland consists of a steroid-secreting cortex and a catecholamine-secreting medulla
The adrenal cortex secretes mineralocorticoids. glucocorticoids, and sex hormones
Mineralocorticoids' major effects are on Na+ and K+ balance and blood pressure homeostasis
Glucocorticoids exert metabolic effects and play a key role in adaptation to stress
Cortisol secretion is regulated by the hypothalamus-pituitary-adrenal cortex axis
The adrenal cortex secrete both male and female sex hormones in both sexes
The adrenal cortex may secrete too much or too little of any of its hormones
The adrenal medulla is a modified sympathetic postganglionic neuron
Epinephrine and norepinephrine vary in their affinities for the different adrenergic receptor types
Epinephrine reinforces the sympathetic nervous system and exerts additional metabolic effects
Sympathetic stimulation of the adrenal medulla is solely responsible for epinephrine release
The stress response is a generalized pattern of reactions to any situation that threatens homeostasis
The multifaceted stress response is coordinated by the hypothalamus
Activation of the stress response by chronic psychosocial stressors may be harmful
Endocrine Control of Fuel Metabolism	719	(9)
Fuel metabolism includes anabolism, catabolism, and interconversions among energy-rich organic molecules
Because food intake is intermittent, nutrients must be stored for use between meals
The brain must be continuously supplied with glucose
Metabolic fuels are stored during the absorptive state and mobilized during the postabsorptive state
Lesser energy sources are tapped as needed
The pancreatic hormones, insulin and glucagon, are most important in regulating fuel metabolism
Insulin lowers blood glucose, amino acid, and fatty acid levels and promotes their storage
The primary stimulus for increased insulin secretion is an increase in blood glucose concentration
The symptoms of diabetes mellitus are characteristic of an exaggerated postabsorptive state
Concepts, Challenges, and Controversies
Diabetics and Insulin: Some Have It and Some Don't	728	(5)
Insulin excess causes brain-starving hypoglycemia
Glucagon in general opposes the actions of insulin
Glucagon secretion is increased during the postabsorptive state
Insulin and glucagon work as a team to maintain blood glucose and fatty acid levels
Glucagon excess can aggravate the hyperglycemia of diabetes mellitus
Epinephrine, cortisol, and growth hormone also exert direct metabolic effects
Endocrine Control of Calcium Metabolism	733	(3)
Plasma Ca2+ must be closely regulated to prevent changes in neuromuscular excitability
Control of Ca2+ metabolism includes regulation of both Ca2+ homeostasis and Ca2+ balance
Parathyroid hormone raises free plasma Ca2+ levels by its effects on bone, kidneys, and intestine
Bone continuously undergoes remodeling
A Closer Look at Exercise Physiology
Osteoporosis: The Bane of Brittle Bones	736	(8)
PTH's immediate effect is to promote the transfer of Ca2+ from bone fluid into plasma
PTH's chronic effect is to promote localized dissolution of bone to release Ca2+ into plasma
PTH acts on the kidneys to conserve Ca2+ and eliminate PO43-
PTH indirectly promotes absorption of Ca2+ and PO43- by the intestine
The primary regulator of PTH secretion is the plasma concentration of free Ca2+
Calcitonin lowers the plasma Ca2+ concentration but is not important in the normal control of Ca2+ metabolism
Vitamin D is actually a hormone that increases calcium absorption in the intestine
Phosphate metabolism is controlled by the same mechanisms that regulate Ca2+ metabolism
Disorders in Ca2+ metabolism may arise from abnormal levels of PTH or vitamin D
Chapter in Perspective: Focus on Homeostasis	742	(2)
Chapter Summary	744	(1)
Review Exercises	745	(1)
Points to Ponder	746	(1)
PhysioEdge Resources	747	(1)
The Reproductive System	748
Introduction	749	(7)
The reproductive system includes the gonads, reproductive tract, and accessory sex glands
Reproductive cells each contain a half set of chromosomes
Gametogenesis is accomplished by meiosis
The sex of an individual is determined by the combination of sex chromosomes
Sexual differentiation along male or female lines depends on the presence or absence of masculinizing determinants
Male Reproductive Physiology	756	(10)
The scrotal location of the testes provides a cooler environment essential for spermatogenesis
The testicular Leydig cells secrete masculinizing testosterone
Spermatogenesis yields an abundance of highly specialized, mobile sperm
Throughout their development, sperm remain intimately associated with Sertoli cells
LH and FSH from the anterior pituitary control testosterone secretion and spermatogenesis
Gonadotropin-releasing hormone activity increases at puberty
The reproductive tract stores and concentrates sperm and increases their fertility
The accessory sex glands contribute the bulk of the semen
Prostaglandins are ubiquitous, locally acting chemical messengers
Sexual Intercourse between Males and Females	766	(3)
The male sex act is characterized by erection and ejaculation
Ejaculation includes emission and expulsion
The female sexual cycle is very similar to the male cycle
Concepts, Challenges, and Controversies
Environmental ``Estrogens'': Bad News for the Reproductive System	769	(1)
Female Reproductive Physiology	770	(10)
Complex cycling characterizes female reproductive physiology
The steps of gametogenesis are the same in both sexes but the timing and outcome sharply differ
The ovarian cycle consists of alternating follicular and luteal phases
The follicular phase is characterized by the development of maturing follicles
The luteal phase is characterized by the presence of a corpus luteum
The ovarian cycle is regulated by complex hormonal interactions
Cyclical uterine changes are caused by hormonal changes during the ovarian cycle
A Closer Look at Exercise Physiology
Menstrual Irregularities: When Cyclists and Other Female Athletes Do Not Cycle	780	(8)
Fluctuating estrogen and progesterone levels produce cyclical changes in cervical mucus
Pubertal changes in females are similar to those in males
Menopause is unique to females
The oviduct is the site of fertilization
The blastocyst implants in the endometrium through the action of its trophoblastic enzymes
The placenta is the organ of exchange between maternal and fetal blood
Concepts, Challenges, and Controversies
The Ways and Means of Contraception	788	(11)
Hormones secreted by the placenta play a critical role in the maintenance of pregnancy
Maternal body systems respond to the increased demands of gestation
Changes during late gestation prepare for parturition
Scientists are closing in on the factors that trigger the onset of parturition
Parturition is accomplished by a positive feedback cycle
Lactation requires multiple hormonal inputs
Breast-feeding is advantageous to both the infant and the mother
The end is a new beginning
Chapter in Perspective: Focus on Homeostasis	799	(1)
Chapter Summary	799	(2)
Review Exercises	801	(1)
Points to Ponder	802	(1)
PhysioEdge Resources	802
Appendix A The Metric System	1	(2)
Appendix B A Review of Chemical Principles	3	(16)
Appendix C Storage, Replication, and Expression of Genetic Information	19	(12)
Appendix D Principles of Quantitative Reasoning	31	(4)
Appendix E Answers to End-of-Chapter Objective Questions, Quantitative Exercises, and Points to Ponder	35	(18)
Appendix F Text References to Exercise Physiology	53
Glossary	1	(1)
Index	1	(1)
Credits	1