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

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ISBN: 9780534395018 | 0534395015
Cover: Hardcover
Copyright: 6/2/2003

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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.

Preface for the Students

Homeostasis: The Foundation of Physiology

(20)

Introduction to Physiology

(1)

Physiology focuses on mechanisms of action

Structure and function are inseparable

Levels of Organization in the Body

(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

(2)

The organism level: The body systems are packaged together into a functional whole body

Concept of Homeostasis

(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?

(3)

Homeostatic Control Systems

(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

(1)

Chapter Summary

(1)

Review Exercises

(1)

Points to Ponder

(1)

PhysioEdge Resources

(1)

Cellular Physiology

(34)

Observations of Cells

(1)

Concepts, Challenges, and Controversies

HeLa Cells: Problems in a ``Growing'' Industry

(1)

An Overview of Cell Structure

(1)

The plasma membrane bounds the cell

The nucleus contains the DNA

The cytoplasm consists of various organelles and the cytosol

Endoplasmic Reticulum

(3)

The rough endoplasmic reticulum synthesizes proteins for secretion and membrane construction

The smooth endoplasmic reticulum packages new proteins in transport vesicles

Golgi Complex

(2)

Transport vesicles carry their cargo to the Golgi complex for further processing

The Golgi complex packages secretory vesicles for release by exocytosis

Lysosomes

(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

(1)

Peroxisomes house oxidative enzymes that detoxify various wastes

Mitochondria

(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?

(1)

The energy stored in ATP is used for synthesis, transport, and mechanical work

Vaults

(1)

Vaults may serve as cellular transport vehicles

Cytosol

(1)

The cytosol is important in intermediary metabolism, ribosomal protein synthesis, and nutrient storage

Cytoskeleton

(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

(1)

Chapter Summary

(1)

Review Exercises

(1)

Points to Ponder

(1)

PhysioEdge Resources

(1)

The Plasma Membrane and Membrane Potential

(42)

Membrane Structure and Composition

(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

(1)

The membrane carbohydrates serve as self-identity markers

Cell-to-Cell Adhesions

(3)

The extracellular matrix serves as the biological ``glue.''

Some cells are directly linked together by specialized cell junctions

Intercellular Communication and Signal Transduction

(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

(1)

Overview of Membrane Transport

(1)

Unassisted Membrane Transport

(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

(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''

(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

(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

(1)

Chapter Summary

(1)

Review Exercises

(2)

Points to Ponder

(1)

PhysioEdge Resources

(1)

Neuronal Physiology

(34)

Introduction

(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

(2)

Appendix B A Review of Chemical Principles

(16)

Appendix C Storage, Replication, and Expression of Genetic Information

(12)

Appendix D Principles of Quantitative Reasoning

(4)

Appendix E Answers to End-of-Chapter Objective Questions, Quantitative Exercises, and Points to Ponder

(18)

Appendix F Text References to Exercise Physiology

Glossary

(1)

Index

(1)

Credits

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

Summary

Table of Contents

Supplemental Materials