Human Physiology: From Cells to Systems

Höfundur: Lauralee Sherwood (Útgáfa: 9)
Human Physiology: From Cells to Systems

Kaup valmöguleikar

Organized around the central theme of homeostasis—how the body meets changing demands while maintaining the internal constancy necessary for all cells and organs to function—HUMAN PHYSIOLOGY helps you appreciate the integrated functioning of the human body. Author Lauralee Sherwood uses clear, straightforward language, analogies, and frequent references to everyday experiences to help you learn and relate to physiology concepts.

Nánar um bókina

Útgefandi
Cengage Learning US
ISBN
9798214118000
Print ISBN
9781285866932
Format
ePub
Útgáfa
9
Höfundar
Lauralee Sherwood
Tungumál
English
Útgefið
2015-01-01
Prent takmörkun á líftíma
100
Prent takmörkun
2
Afritunar takmörkun
2

Kaflar

  • Cover Page
  • Title Page
  • Copyright Page
  • Dedication
  • Preface
  • 1. Introduction to Physiology and Homeostasis
  • 1.1. Introduction to Physiology
  • Physiology focuses on mechanisms of action.
  • Structure and function are inseparable.
  • 1.2. Levels of Organization in the Body
  • 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.
  • The organism level: The body systems are packaged into a functional whole body.
  • 1.3. Concept of Homeostasis
  • Body cells are in contact with a privately maintained internal environment.
  • Body systems maintain homeostasis, a dynamic steady state in the internal environment.
  • Concepts, Challenges, and Controversies Stem Cell Science and Regenerative Medicine: Making Defective Body Parts Like New Again
  • A Closer Look at Exercise Physiology What Is Exercise Physiology?
  • 1.4. Homeostatic Control Systems
  • 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.
  • Homeostasis: Chapter in Perspective
  • Chapter 1 Study Card
  • Review Exercises
  • 2. Cell Physiology
  • 2.1. Cell Theory and Discovery
  • 2.2. An Overview of Cell Structure
  • The plasma membrane bounds the cell.
  • The nucleus contains the DNA.
  • The cytoplasm consists of various organelles, the cytoskeleton, and the cytosol.
  • 2.3. Endoplasmic Reticulum and Segregated Synthesis
  • The rough ER synthesizes proteins for secretion and membrane construction.
  • The smooth ER packages new proteins in transport vesicles.
  • Misfolded proteins are destroyed by the ubiquitin-proteasome pathway.
  • 2.4. Golgi Complex and Exocytosis
  • Transport vesicles carry their cargo to the Golgi complex for further processing.
  • The Golgi complex packages secretory vesicles for release by exocytosis.
  • 2.5. Lysosomes and Endocytosis
  • Lysosomes digest extracellular material brought into the cell by phagocytosis.
  • Lysosomes remove worn-out organelles.
  • 2.6. Peroxisomes and Detoxification
  • Peroxisomes house oxidative enzymes that detoxify various wastes.
  • 2.7. Mitochondria and ATP Production
  • Mitochondria are enclosed by two membranes.
  • Mitochondria form a mitochondrial reticulum in some cell types.
  • Mitochondria play a major role in generating ATP.
  • The cell generates more energy in aerobic than in anaerobic conditions.
  • The energy stored within ATP is used for synthesis, transport, and mechanical work.
  • Mitochondria play a key role in programmed cell death.
  • A Closer Look at Exercise Physiology Aerobic Exercise: What For and How Much?
  • 2.8. Vaults as Cellular Trucks
  • Vaults may serve as cellular transport vehicles.
  • Concepts, Challenges, and Controversies Apoptosis: Programmed Cell Suicide
  • 2.9. Cytosol: Cell Gel
  • The cytosol is important in intermediary metabolism, ribosomal protein synthesis, and nutrient storage.
  • 2.10. Cytoskeleton: Cell “Bone and Muscle”
  • Microtubules help maintain asymmetric 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.
  • Homeostasis: Chapter in Perspective
  • Chapter 2 Study Card
  • Review Exercises
  • 3. The Plasma Membrane and Membrane Potential
  • 3.1. Membrane Structure and Functions
  • 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 various specific membrane functions.
  • Concepts, Challenges, and Controversies Cystic Fibrosis: A Fatal Defect in Membrane Transport
  • The membrane carbohydrates serve as self-identity markers.
  • 3.2. Cell-to-Cell Adhesions
  • The extracellular matrix serves as biological “glue.”
  • Some cells are directly linked by specialized cell junctions.
  • 3.3. Overview of Membrane Transport
  • Lipid-soluble substances and small water-soluble substances can permeate the plasma membrane unassisted.
  • Active forces use energy to move particles across the membrane, but passive forces do not.
  • 3.4. Unassisted Membrane Transport
  • Particles that can permeate the membrane diffuse passively down their concentration gradient.
  • Ions that can permeate the membrane also move passively along their electrical gradient.
  • Osmosis is the net diffusion of water down its own concentration gradient.
  • Tonicity refers to the effect the concentration of nonpenetrating solutes in a solution has on cell volume.
  • 3.5. Assisted Membrane Transport
  • Carrier-mediated transport is accomplished by a membrane carrier changing its shape.
  • A Closer Look at Exercise Physiology Exercising Muscles Have a “Sweet Tooth”
  • Facilitated diffusion is passive carrier-mediated transport.
  • Active transport is carrier mediated and uses energy.
  • With vesicular transport, material is moved into or out of the cell wrapped in membrane.
  • 3.6. Membrane Potential
  • Membrane potential is a separation of opposite charges across the plasma membrane.
  • Membrane potential results from differences in the concentration and permeability of key ions.
  • Homeostasis: Chapter in Perspective
  • Chapter 3 Study Card
  • Review Exercises
  • 4. Principles of Neural and Hormonal Communication
  • 4.1. Introduction to Neural Communication
  • Nerve and muscle are excitable tissues.
  • Membrane potential becomes less negative during depolarization and more negative during hyperpolarization.
  • Electrical signals are produced by changes in ion movement across the plasma membrane.
  • 4.2. Graded Potentials
  • The stronger a triggering event, the larger the resultant graded potential.
  • Graded potentials spread by passive current flow.
  • Graded potentials die out over short distances.
  • 4.3. Action Potentials
  • 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 action potentials and limits their frequency.
  • 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.
  • Fiber diameter also influences the velocity of action potential propagation.
  • 4.4. Synapses and Neuronal Integration
  • Synapses are typically junctions between presynaptic and postsynaptic neurons.
  • Concepts, Challenges, and Controversies Multiple Sclerosis: Myelin—Going, Going, Gone
  • Concepts, Challenges, and Controversies Regeneration: PNS Axons Can Do It, But CNS Axons Cannot
  • A neurotransmitter carries the signal across a synapse.
  • Some synapses excite, whereas others inhibit, the postsynaptic neuron.
  • Each neurotransmitter-receptor combination always produces the same response.
  • Neurotransmitters are quickly removed from the synaptic cleft.
  • The grand postsynaptic potential depends on the sum of the activities of all presynaptic inputs.
  • Some neurons secrete neuromodulators in addition to neurotransmitters.
  • Presynaptic inhibition or facilitation can selectively alter the effectiveness of a presynaptic input.
  • Drugs and diseases can modify synaptic transmission.
  • Neurons are linked through complex converging and diverging pathways.
  • 4.5. Intercellular Communication and Signal Transduction
  • Communication among cells is largely orchestrated by extracellular chemical messengers.
  • Extracellular chemical messengers bring about cell responses by signal transduction.
  • Some water-soluble extracellular messengers open chemically gated receptor-channels.
  • Some water-soluble extracellular messengers activate receptor-enzymes.
  • Most water-soluble extracellular chemical messengers activate second-messenger pathways via G-protein-coupled receptors.
  • 4.6. Introduction to Paracrine Communication
  • Cytokines act locally to regulate immune responses.
  • Eicosanoids are locally acting chemical messengers derived from plasma membrane.
  • 4.7. Introduction to Hormonal Communication
  • Hormones are classified chemically as hydrophilic or lipophilic.
  • The mechanisms of synthesis, storage, and secretion of hormones vary according to their chemical differences.
  • Hydrophilic hormones dissolve in the plasma; lipophilic hormones are transported by plasma proteins.
  • Hormones generally produce their effect by altering intracellular proteins.
  • Hydrophilic hormones alter preexisting proteins via second-messenger systems.
  • By stimulating genes, lipophilic hormones promote synthesis of new proteins.
  • 4.8. Comparison of the Nervous and Endocrine Systems
  • The nervous system is “wired,” and the endocrine system is “wireless.”
  • Neural specificity is a result of anatomic proximity, and endocrine specificity is a result of receptor specialization.
  • The nervous and endocrine systems have their own realms of authority but interact functionally.
  • Homeostasis: Chapter in Perspective
  • Chapter 4 Study Card
  • Review Exercises
  • 5. The Central Nervous System
  • 5.1. Organization and Cells of the Nervous System
  • The nervous system is organized into the central nervous system and the peripheral nervous system.
  • The three functional classes of neurons are afferent neurons, efferent neurons, and interneurons.
  • Glial cells support the interneurons physically, metabolically, and functionally.
  • 5.2. Protection and Nourishment of the Brain
  • 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 regulates exchanges between the blood and brain.
  • The brain depends on constant delivery of oxygen and glucose by the blood.
  • Concepts, Challenges, and Controversies Strokes: A Deadly Domino Effect
  • 5.3. Overview of the Central Nervous System
  • 5.4. Cerebral Cortex
  • The cerebral cortex is an outer shell of gray matter covering an inner core of white matter.
  • Neurons in different regions of the cerebral cortex may fire in rhythmic synchrony.
  • 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 accomplish somatosensory processing.
  • The primary motor cortex located in the frontal lobes controls the skeletal muscles.
  • Higher motor areas are also 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 regions of the cortex control different aspects of language.
  • The association areas of the cortex are involved in many higher functions.
  • The cerebral hemispheres have some degree of specialization.
  • The cortex has a default mode network that is most active when the mind wanders.
  • 5.5. Basal Nuclei, Thalamus, and Hypothalamus
  • 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.
  • 5.6. Emotion, Behavior, and Motivation
  • The limbic system plays a key role in emotion.
  • The limbic system and higher cortex participate in controlling basic behavioral patterns.
  • Motivated behaviors are goal directed.
  • Norepinephrine, dopamine, and serotonin are neurotransmitters in pathways for emotions and behavior.
  • 5.7. Learning and Memory
  • Learning is the acquisition of knowledge as a result of experiences.
  • Memory is laid down in stages.
  • Short-term memory and long-term memory involve different molecular mechanisms.
  • Short-term memory involves transient changes in synaptic activity.
  • Long-term memory involves formation of new, permanent synaptic connections.
  • Memory traces are present in multiple regions of the brain.
  • 5.8. Cerebellum
  • The cerebellum is important in balance and in planning and executing voluntary movement.
  • Concepts, Challenges, and Controversies Alzheimer’s Disease: A Tale of Beta Amyloid Plaques, Tau Tangles, and Dementia
  • 5.9. Brain Stem
  • The brain stem is a vital link between the spinal cord and higher brain regions.
  • Consciousness refers to awareness of one’s existence, thoughts, and surroundings.
  • An electroencephalogram is a record of postsynaptic activity in cortical neurons.
  • 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.
  • Impaired states of consciousness are associated with minimal or no awareness.
  • 5.10. Spinal Cord
  • 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.
  • The spinal cord is responsible for the integration of many innate reflexes.
  • A Closer Look at Exercise Physiology Swan Dive or Belly Flop: It’s a Matter of CNS Control
  • Homeostasis: Chapter in Perspective
  • Chapter 5 Study Card
  • Review Exercises
  • 6. The Peripheral Nervous System: Afferent Division; Special Senses
  • 6.1. Receptor Physiology
  • 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.
  • Visceral afferents carry subconscious input; sensory afferents carry conscious input.
  • Each somatosensory pathway is “labeled” according to modality and location.
  • A Closer Look at Exercise Physiology Back Swings and Prejump Crouches: What Do They Share in Common?
  • Acuity is influenced by receptive field size and lateral inhibition.
  • Perception is the conscious awareness of surroundings derived from interpretation of sensory input.
  • 6.2. Pain
  • Stimulation of nociceptors elicits the perception of pain plus motivational and emotional responses.
  • The brain has a built-in analgesic system.
  • 6.3. Eye: Vision
  • Protective mechanisms help prevent eye injuries.
  • 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 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; cones provide sharp color vision during the day.
  • Color vision depends on the ratios of stimulation of the three cone types.
  • The sensitivity of the eyes can vary markedly through dark and light adaptation.
  • Visual information is modified and separated before reaching the visual cortex.
  • The thalamus and visual cortex elaborate the visual message.
  • Visual input goes to other areas of the brain not involved in vision perception.
  • Concepts, Challenges, and Controversies “Seeing” with the Tongue or the Ear
  • Some sensory input may be detected by multiple sensory-processing areas in the brain.
  • 6.4. Ear: Hearing and Equilibrium
  • 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 vibration.
  • The auditory cortex is mapped according to tone.
  • Deafness is caused by defects in either conduction or neural processing of sound waves.
  • The vestibular apparatus is important for equilibrium by detecting head position and motion.
  • 6.5. Chemical Senses: Taste and Smell
  • Taste receptor cells are located primarily within tongue taste buds.
  • Taste discrimination is coded by patterns of activity in various taste bud receptors.
  • The gut and airways “taste” too.
  • 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.
  • Homeostasis: Chapter in Perspective
  • Chapter 6 Study Card
  • Review Exercises
  • 7. The Peripheral Nervous System: Efferent Division
  • 7.1. Autonomic Nervous System
  • An autonomic nerve pathway consists of a two-neuron chain.
  • Parasympathetic postganglionic fibers release acetylcholine; sympathetic ones release norepinephrine.
  • The sympathetic and parasympathetic nervous systems dually innervate most visceral organs.
  • The adrenal medulla is a modified part of the sympathetic nervous system.
  • Several receptor types are available for each autonomic neurotransmitter.
  • Many regions of the CNS are involved in the control of autonomic activities.
  • 7.2. Somatic Nervous System
  • Motor neurons supply skeletal muscle.
  • Motor neurons are the final common pathway.
  • 7.3. Neuromuscular Junction
  • Motor neurons and skeletal muscle fibers are chemically linked at neuromuscular junctions.
  • ACh is the neuromuscular junction neurotransmitter.
  • Acetylcholinesterase ends ACh 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
  • Homeostasis: Chapter in Perspective
  • Chapter 7 Study Card
  • Review Exercises
  • 8. Muscle Physiology
  • 8.1. Structure of Skeletal Muscle
  • Skeletal muscle fibers are striated by a highly organized internal arrangement.
  • Myosin forms the thick filaments.
  • Actin is the main structural component of the thin filaments.
  • 8.2. Molecular Basis of Skeletal Muscle Contraction
  • During contraction, cycles of cross-bridge binding and bending pull the thin filaments inward.
  • Calcium is the link between excitation and contraction.
  • 8.3. Skeletal Muscle Mechanics
  • Whole muscles are groups of muscle fibers bundled together and attached to bones.
  • Muscle tension is transmitted to bone as the contractile component tightens the series-elastic component.
  • The three primary types of contraction are isotonic, isokinetic, 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.
  • 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 primarily from a sustained elevation in cytosolic C a 2 + .
  • At the optimal muscle length, maximal tension can be developed.
  • 8.4. Skeletal Muscle Metabolism and Fiber Types
  • Muscle fibers have alternate pathways for forming ATP.
  • Fatigue may be of muscle or central origin.
  • Increased O 2 consumption is necessary to recover from exercise.
  • The three types of skeletal muscle fibers differ 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?
  • 8.5. Control of Motor Movement
  • Motor activity can be classified as reflex, voluntary, or rhythmic.
  • Concepts, Challenges, and Controversies Muscular Dystrophy: When One Small Step Is a Big Deal
  • Multiple neural inputs influence motor unit output.
  • Muscle receptors provide afferent information needed to control skeletal muscle activity.
  • Skeletal muscle reflexes can be triggered by painful stimulation of the skin.
  • 8.6. Smooth and Cardiac Muscle
  • Smooth muscle cells are small and unstriated.
  • Smooth muscle cells are turned on by C a 2 + -dependent phosphorylation of myosin.
  • Phasic smooth muscle contracts in bursts; tonic smooth muscle maintains tone.
  • 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.
  • Homeostasis: Chapter in Perspective
  • Chapter 8 Study Card
  • Review Exercises
  • 9. Cardiac Physiology
  • 9.1. Anatomy of the Heart
  • The heart is positioned in the middle of the thoracic cavity.
  • The heart is a dual pump.
  • Pressure-operated heart valves ensure that blood flows in the right 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.
  • 9.2. Electrical Activity of the Heart
  • 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.
  • A long refractory period prevents tetanus of cardiac muscle.
  • The ECG is a record of the overall spread of electrical activity through the heart.
  • Different parts of the ECG record can be correlated to specific cardiac events.
  • The ECG can detect abnormal heart rates and rhythms and heart muscle damage.
  • A Closer Look at Exercise Physiology The What, Who, and When of Stress Testing
  • 9.3. Mechanical Events of the Cardiac Cycle
  • The heart alternately contracts to empty and relaxes to fill.
  • Two normal heart sounds are associated with valve closures.
  • Turbulent blood flow produces heart murmurs.
  • 9.4. Cardiac Output and Its Control
  • Cardiac output depends on heart rate and 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.
  • Sympathetic stimulation increases the contractility of the heart.
  • High blood pressure increases the workload of the heart.
  • A failing heart cannot pump out enough blood.
  • 9.5. Nourishing the Heart Muscle
  • The heart receives most of its blood supply through the coronary circulation during diastole.
  • Atherosclerotic coronary artery disease can deprive the heart of essential O 2 .
  • Concepts, Challenges, and Controversies Atherosclerosis: Cholesterol and Beyond
  • Homeostasis: Chapter in Perspective
  • Chapter 9 Study Card
  • Review Exercises
  • 10. The Blood Vessels and Blood Pressure
  • 10.1. Patterns and Physics of Blood Flow
  • To maintain homeostasis, reconditioning organs receive blood flow in excess of their needs.
  • Blood flow through a vessel depends on the pressure gradient and vascular resistance.
  • The vascular tree consists of arteries, arterioles, capillaries, venules, and veins.
  • 10.2. Arteries
  • Arteries serve as rapid-transit passageways to the organs 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.
  • 10.3. Arterioles
  • 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 organs’ needs.
  • Local histamine release pathologically dilates arterioles.
  • The myogenic response of arterioles to stretch helps tissues autoregulate their blood flow.
  • Arterioles release vasodilating NO in response to an increase in shear stress.
  • Local heat application dilates arterioles and cold application constricts them.
  • Extrinsic control of arteriolar radius is important in regulating blood pressure.
  • The cardiovascular control center and several hormones regulate blood pressure.
  • 10.4. Capillaries
  • 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 blood and cells.
  • Diffusion across 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 for return of interstitial fluid to the blood.
  • Edema occurs when too much interstitial fluid accumulates.
  • 10.5. Veins
  • Venules communicate chemically with nearby arterioles.
  • Veins serve as a blood reservoir and as passageways back to the heart.
  • Venous return is enhanced by several extrinsic factors.
  • 10.6. Blood Pressure
  • Blood pressure is regulated by controlling cardiac output, total peripheral resistance, and blood volume.
  • The baroreceptor reflex is a short-term mechanism for regulating blood pressure.
  • Other reflexes and responses influence blood pressure.
  • Hypertension is a national public-health problem, but its causes are largely unknown.
  • A Closer Look at Exercise Physiology The Body Gets a Jump on Jogging: Cardiovascular Changes during Exercise
  • Concepts, Challenges, and Controversies The Ups (Causes) and Downs (Treatments) of Hypertension
  • Orthostatic hypotension results from transient inadequate sympathetic activity.
  • Circulatory shock can become irreversible.
  • Homeostasis: Chapter in Perspective
  • Chapter 10 Study Card
  • Review Exercises
  • 11. The Blood
  • 11.1. Plasma
  • The hematocrit is the packed cell volume of blood; the rest of the volume is plasma.
  • Plasma water is a transport medium for many inorganic and organic substances.
  • Many of the functions of plasma are carried out by plasma proteins.
  • 11.2. Erythrocytes
  • Erythrocytes are well designed for their main function of O 2 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?
  • Anemia can be caused by a variety of disorders.
  • Polycythemia is an excess of circulating erythrocytes.
  • Blood types depend on surface antigens on erythrocytes.
  • Concepts, Challenges, and Controversies In Search of a Blood Substitute
  • 11.3. Leukocytes
  • Leukocytes primarily function as defense agents outside the blood.
  • There are five types of leukocytes.
  • Leukocytes are produced at varying rates depending on the body’s changing needs.
  • 11.4. Platelets and Hemostasis
  • Platelets are cell fragments shed from megakaryocytes.
  • Hemostasis prevents blood loss from damaged small vessels.
  • Vascular spasm reduces blood flow through an injured vessel.
  • Platelets aggregate to form a plug at a vessel injury.
  • Clot formation results from a triggered chain reaction involving plasma clotting factors.
  • Fibrinolytic plasmin dissolves clots.
  • Inappropriate clotting produces thromboembolism.
  • Hemophilia is the primary condition that produces excessive bleeding.
  • Homeostasis: Chapter in Perspective
  • Chapter 11 Study Card
  • Review Exercises
  • 12. Body Defenses
  • 12.1. Immune System: Targets, Effectors, Components
  • 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.
  • 12.2. Innate Immunity
  • Inflammation is a nonspecific response to foreign invasion or tissue damage.
  • Inflammation is an underlying culprit in many common, chronic illnesses.
  • Nonsteroidal anti-inflammatory drugs and glucocorticoids suppress inflammation.
  • Interferon transiently inhibits multiplication of viruses in most cells.
  • Natural killer cells destroy virus-infected cells and cancer cells on first exposure to them.
  • The complement system punches holes in microorganisms.
  • Newly discovered immune cells straddle innate and adaptive defenses.
  • 12.3. Adaptive Immunity: General Concepts
  • Adaptive immune responses include antibody-mediated immunity and cell-mediated immunity.
  • An antigen induces an immune response against itself.
  • 12.4. B Lymphocytes: Antibody-Mediated Immunity
  • The antigens to which B cells respond can be T-independent or T-dependent.
  • 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.
  • Active immunity is self-generated; passive immunity is “borrowed.”
  • The huge repertoire of B cells is built by reshuffling a small set of gene fragments.
  • Concepts, Challenges, and Controversies Vaccination: A Victory Over Many Dreaded Diseases
  • 12.5. T Lymphocytes: Cell-Mediated Immunity
  • T cells bind directly with their targets.
  • The three types of T cells are cytotoxic, helper, and regulatory T cells.
  • Cytotoxic T cells secrete chemicals that destroy target cells.
  • Helper T cells secrete chemicals that amplify the activity of other immune cells.
  • Regulatory T cells suppress immune responses.
  • T cells respond only to antigens presented to them by antigen-presenting cells.
  • The major histocompatibility complex is the code for self-antigens.
  • The immune system is normally tolerant of self-antigens.
  • Autoimmune diseases arise from loss of tolerance to specific self-antigens.
  • An interplay among immune cells and interferon defends against cancer.
  • 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?
  • 12.6. Immune Diseases
  • Immunodeficiency diseases result from insufficient immune responses.
  • Allergies are inappropriate immune attacks against harmless environmental substances.
  • 12.7. External Defenses
  • The skin consists of an outer protective epidermis and an inner, connective tissue dermis.
  • Specialized cells in the epidermis produce melanin, keratin, and vitamin D and participate in immune defense.
  • Protective measures within body cavities discourage pathogen invasion into the body.
  • Homeostasis: Chapter in Perspective
  • Chapter 12 Study Card
  • Review Exercises
  • 13. The Respiratory System
  • 13.1. Respiratory Anatomy
  • The respiratory system does not participate in all steps of respiration.
  • The respiratory airways conduct air between the atmosphere and alveoli.
  • The gas-exchanging alveoli are thin-walled air sacs encircled by pulmonary capillaries.
  • The lungs occupy much of the thoracic cavity.
  • A pleural sac separates each lung from the thoracic wall.
  • 13.2. Respiratory Mechanics
  • Interrelationships among pressures inside and outside the lungs are important in ventilation.
  • The transmural pressure gradient stretches the lungs to fill the larger thoracic cavity.
  • Airway resistance influences airflow rates.
  • Airway resistance is abnormally increased with chronic obstructive pulmonary disease.
  • The lungs’ elastic behavior results from elastin fibers 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 about “half full.”
  • Alveolar ventilation is less than pulmonary ventilation because of dead space.
  • Local controls act on bronchiolar and arteriolar smooth muscle to match airflow to blood flow.
  • 13.3. Gas Exchange
  • Gases move down partial pressure gradients.
  • O 2 enters and C O 2 leaves the blood in the lungs 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.
  • 13.4. Gas Transport
  • Most O 2 in the blood is transported bound to hemoglobin.
  • The P O 2 is the primary factor determining the percent hemoglobin saturation.
  • Hemoglobin promotes the net transfer of O 2 at both the alveolar and the tissue levels.
  • Factors at the tissue level promote unloading of O 2 from hemoglobin.
  • Hemoglobin has a much higher affinity for carbon monoxide than for O 2 .
  • Most C O 2 is transported in the blood as bicarbonate.
  • Various respiratory states are characterized by abnormal blood-gas levels.
  • 13.5. Control of Respiration
  • Respiratory centers in the brain stem establish a rhythmic breathing pattern.
  • Concepts, Challenges, and Controversies Effects of Heights and Depths on the Body
  • Ventilation magnitude is adjusted in response to three chemical factors: P O 2 , P C O 2 , and H + .
  • Decreased arterial P O 2 increases ventilation only as an emergency mechanism.
  • C O 2 -generated H + in the brain is normally the main regulator of ventilation
  • Adjustments in ventilation in response to changes in arterial H + are important in acid-base balance.
  • Exercise profoundly increases ventilation by unclear mechanisms.
  • Ventilation can be influenced by factors unrelated to the need for gas exchange.
  • During apnea, a person “forgets to breathe”; during dyspnea, a person feels “short of breath.”
  • A Closer Look at Exercise Physiology How to Find Out How Much Work You’re Capable of Doing
  • Homeostasis: Chapter in Perspective
  • Chapter 13 Study Card
  • Review Exercises
  • 14. The Urinary System
  • 14.1. Kidneys: Functions, Anatomy, and Basic Processes
  • The kidneys perform a variety of functions aimed at maintaining homeostasis.
  • The kidneys form urine; the rest of the urinary system carries it 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.
  • 14.2. Glomerular Filtration
  • The glomerular membrane is considerably more permeable than capillaries elsewhere.
  • A Closer Look at Exercise Physiology When Protein in the Urine Does Not Mean Kidney Disease
  • Glomerular capillary blood pressure is the major force that causes glomerular filtration.
  • Changes in GFR result mainly from 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.
  • 14.3. Tubular Reabsorption
  • Tubular reabsorption is tremendous, highly selective, and variable.
  • Tubular reabsorption involves transepithelial transport.
  • N a + reabsorption depends on the Na + - K + ATPase pump in the basolateral membrane.
  • Aldosterone stimulates Na + reabsorption in the distal and collecting tubules.
  • The natriuretic peptides inhibit 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 actively reabsorbed substance not regulated by the kidneys.
  • Phosphate is an actively reabsorbed substance regulated by the kidneys.
  • Active Na + reabsorption is responsible for passive reabsorption of Cl - , H 2 O , and urea.
  • In general, unwanted waste products are not reabsorbed.
  • 14.4. Tubular Secretion
  • Hydrogen ion secretion is important in acid-base balance.
  • Potassium ion secretion is controlled by aldosterone.
  • Organic anion and cation secretion hastens elimination of foreign compounds.
  • 14.5. Urine Excretion and Plasma Clearance
  • Plasma clearance is the volume of plasma cleared of a particular substance per minute.
  • Clearance rates for inulin and PAH can be used to determine the filtration fraction.
  • The kidneys can excrete urine of varying concentrations depending on body needs.
  • Long Henle’s loops establish the vertical osmotic gradient by countercurrent multiplication.
  • Vasopressin controls variable H 2 O reabsorption in the final tubular segments.
  • The vasa recta preserve the vertical osmotic gradient by countercurrent exchange.
  • Water reabsorption is only partially linked to solute reabsorption.
  • Renal failure has wide-ranging consequences.
  • 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
  • Homeostasis: Chapter in Perspective
  • Regulatory Functions
  • Excretory Functions
  • Hormonal Functions
  • Metabolic Functions
  • Chapter 14 Study Card
  • Review Exercises
  • 15. Fluid and Acid-Base Balance
  • 15.1. Balance Concept
  • 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.
  • 15.2. Fluid Balance
  • Body water is distributed between the ICF and the ECF compartments.
  • Plasma and interstitial fluid are similar in composition, but 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.
  • Controlling ECF osmolarity prevents changes in ICF volume.
  • During ECF hypertonicity, cells shrink as H 2 O leaves them.
  • A Closer Look at Exercise Physiology A Potentially Fatal Clash: When Exercising Muscles and Cooling Mechanisms Compete for an Inadequate Plasma Volume
  • During ECF hypotonicity, the cells swell as H 2 O enters them.
  • No water moves into or out of cells during an ECF isotonic fluid gain or loss.
  • Vasopressin control of free H 2 O balance is important in regulating ECF osmolarity.
  • Vasopressin secretion and thirst are largely triggered simultaneously.
  • 15.3. Acid-Base Balance
  • 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 H 2 CO 3 : HCO 3 - buffer pair is the primary ECF buffer for noncarbonic acids.
  • The protein buffer system is primarily important intracellularly.
  • The hemoglobin buffer system buffers H + generated from CO 2 .
  • 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 CO 2 removal.
  • The respiratory system serves as the second line of defense against changes in [ H + ] .
  • The kidneys adjust their rate of H + excretion by varying the extent of H + secretion.
  • The kidneys conserve or excrete HCO 3 - depending on the plasma [ H + ] .
  • The kidneys secrete ammonia during acidosis to buffer secreted H + .
  • The kidneys are a powerful third line of defense against changes in [ H + ] .
  • Acid-base imbalances can arise from either respiratory or metabolic disturbances.
  • Respiratory acidosis arises from an increase in [ CO 2 ] .
  • Respiratory alkalosis arises from a decrease in [ CO 2 ] .
  • Metabolic acidosis is associated with a fall in [ HCO 3 - ] .
  • Metabolic alkalosis is associated with an elevation in [ HCO 3 - ] .
  • Homeostasis: Chapter in Perspective
  • Chapter 15 Study Card
  • Review Exercises
  • 16. The Digestive System
  • 16.1. General Aspects of Digestion
  • 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 and hormonal pathways.
  • 16.2. Mouth
  • The oral cavity is the entrance to the digestive tract.
  • The teeth mechanically break down food.
  • Saliva begins carbohydrate digestion and helps swallowing, speech, taste, and oral health.
  • Salivary secretion is continuous and can be reflexly increased.
  • Digestion in the mouth is minimal; no absorption of nutrients occurs.
  • 16.3. Pharynx and Esophagus
  • Swallowing is a sequentially programmed all-or-none reflex.
  • During swallowing, food is prevented from entering the wrong passageways.
  • The pharyngoesophageal sphincter prevents air from entering the digestive tract.
  • Peristaltic waves push food through the esophagus.
  • The gastroesophageal sphincter prevents reflux of gastric contents.
  • Esophageal secretion is entirely protective.
  • 16.4. Stomach
  • 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?
  • 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 is secreted by parietal cells and activates pepsinogen.
  • Pepsinogen is activated to pepsin, which begins protein digestion.
  • Mucus is protective.
  • Intrinsic factor is essential for absorption of vitamin B 12 .
  • 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 gastric mucosal barrier protects the stomach lining from gastric secretions.
  • Carbohydrate digestion continues in the body of the stomach; protein digestion begins in the antrum.
  • The stomach absorbs alcohol and aspirin but no food.
  • 16.5. Pancreatic and Biliary Secretions
  • Concepts, Challenges, and Controversies Ulcers: When Bugs Break the Barrier
  • The pancreas is a mixture of exocrine and endocrine tissue.
  • The exocrine pancreas secretes digestive enzymes and an alkaline fluid.
  • Pancreatic exocrine secretion is regulated by secretin and CCK.
  • The liver performs various important functions, including bile production.
  • 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.
  • Bile salts stimulate bile secretion; CCK promotes gallbladder emptying.
  • Bilirubin is a waste product excreted in the bile.
  • Hepatitis and cirrhosis are the most common liver disorders.
  • 16.6. Small Intestine
  • 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 within the brush-border membrane.
  • 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 H 2 O absorption.
  • Digested carbohydrates and proteins 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.
  • 16.7. Large Intestine
  • The large intestine is primarily a drying and storage organ.
  • Concepts, Challenges, and Controversies Oral Rehydration Therapy: Sipping a Simple Solution Saves Lives
  • Haustral contractions slowly shuffle the colonic contents back and forth.
  • Mass movements propel feces long distances.
  • Feces are eliminated by the defecation reflex.
  • Constipation occurs when the feces become too dry.
  • Intestinal gases are absorbed or expelled.
  • 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.
  • 16.8. Overview of the GI Hormones
  • Gastrin
  • Homeostasis: Chapter in Perspective
  • Chapter 16 Study Card
  • Review Exercises
  • 17. Energy Balance and Temperature Regulation
  • 17.1. Energy Balance
  • 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.
  • A Closer Look at Exercise Physiology What the Scales Don’t Tell You
  • People suffering from anorexia nervosa have a pathological fear of gaining weight.
  • 17.2. Temperature Regulation
  • Internal core temperature is homeostatically maintained at 100 ° F ‍ ( 37.8 ° C ) .
  • Heat input must balance heat output to maintain a stable core temperature.
  • Heat exchange takes place by radiation, conduction, convection, and evaporation.
  • Sweating is a regulated evaporative heat-loss process.
  • 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.
  • Concepts, Challenges, and Controversies The Extremes of Heat and Cold Can Be Fatal
  • Hyperthermia can occur unrelated to infection.
  • Homeostasis: Chapter in Perspective
  • Chapter 17 Study Card
  • Review Exercises
  • 18. Principles of Endocrinology; The Central Endocrine Glands
  • 18.1. General Principles of Endocrinology
  • Hormones exert a variety of regulatory effects throughout the body.
  • The effective plasma concentration of a hormone is influenced by the hormone’s secretion, peripheral conversion, transport, inactivation, and excretion.
  • The effective plasma concentration of a hormone is normally regulated by changes in the rate of its secretion.
  • 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.
  • 18.2. Hypothalamus and Pituitary
  • The pituitary gland consists of anterior and posterior lobes.
  • The hypothalamus and posterior pituitary act as a unit to secrete vasopressin and oxytocin.
  • Most anterior pituitary hormones are tropic.
  • A Closer Look at Exercise Physiology The Endocrine Response to the Challenge of Combined Heat and Marching Feet
  • Hypothalamic releasing and inhibiting hormones help regulate anterior pituitary hormone secretion.
  • Target-gland hormones inhibit hypothalamic and anterior pituitary hormone secretion via negative feedback.
  • 18.3. Endocrine Control of Growth
  • Growth depends on GH but is influenced by other factors.
  • GH is essential for growth, but it also directly exerts metabolic effects not related to growth.
  • GH mostly exerts its growth-promoting effects indirectly by stimulating insulin-like growth factors.
  • GH, through IGF-I, promotes growth of soft tissues by stimulating hypertrophy and hyperplasia.
  • Bone grows in thickness and in length by different mechanisms, both stimulated by GH.
  • GH secretion is regulated by two hypophysiotropic hormones.
  • Abnormal GH secretion results in aberrant growth patterns.
  • Concepts, Challenges, and Controversies Growth and Youth in a Bottle?
  • Other hormones besides growth hormone are essential for normal growth.
  • 18-4. Pineal Gland and Circadian Rhythms
  • The suprachiasmatic nucleus is the master biological clock.
  • Concepts, Challenges, and Controversies Tinkering with Our Biological Clocks
  • Melatonin helps keep the body’s circadian rhythms in time with the light-dark cycle.
  • Homeostasis: Chapter in Perspective
  • Chapter 18 Study Card
  • Review Exercises
  • 19. The Peripheral Endocrine Glands
  • 19.1. Thyroid Gland
  • The major cells that secrete thyroid hormone are organized into colloid-filled follicles.
  • Thyroid hormone is synthesized and stored on the thyroglobulin molecule.
  • To secrete thyroid hormone, the follicular cells phagocytize thyroglobulin-laden colloid.
  • Thyroid hormone increases the basal metabolic rate and exerts other effects.
  • 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.
  • 19.2. Adrenal Glands
  • Each adrenal gland consists of a steroid-secreting cortex and a catecholamine-secreting medulla.
  • The adrenal cortex secretes mineralocorticoids, glucocorticoids, and sex hormones.
  • The major effects of mineralocorticoids 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 secretes both male and female sex hormones in both sexes.
  • The adrenal cortex may secrete too much or too little of any of its hormones.
  • Concepts, Challenges, and Controversies Still a Big Question: Why Do We Age?
  • The adrenal medulla consists of modified sympathetic postganglionic neurons.
  • Epinephrine and norepinephrine vary in their affinities for different receptor types.
  • Epinephrine reinforces the sympathetic nervous system and exerts metabolic effects.
  • Epinephrine is released only on sympathetic stimulation of the adrenal medulla.
  • 19.3. Integrated Stress Response
  • 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.
  • 19.4. Endocrine Pancreas and Control of Fuel Metabolism
  • 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, fatty acid, and amino acid levels and promotes their storage.
  • The primary stimulus for increased insulin secretion is an increase in blood glucose.
  • 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
  • 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.
  • The hypothalamus plays a role in controlling glucose homeostasis.
  • 19.5. Parathyroid Glands and Control of Calcium Metabolism
  • Plasma Ca 2 + must be closely regulated to prevent changes in neuromuscular excitability.
  • Control of Ca 2 + metabolism includes regulation of both Ca 2 + homeostasis and Ca 2 + balance.
  • Parathyroid hormone raises free plasma Ca 2 + , a life-saving effect.
  • Bone continuously undergoes remodeling.
  • Mechanical stress favors bone deposition.
  • PTH raises plasma Ca 2 + by withdrawing Ca 2 + from the bone bank.
  • PTH’s immediate effect is to promote transfer of Ca 2 + from bone fluid into plasma.
  • PTH’s chronic effect is to promote localized dissolution of bone to release Ca 2 + into plasma.
  • A Closer Look at Exercise Physiology Osteoporosis: The Bane of Brittle Bones
  • PTH acts on the kidneys to conserve Ca 2 + and eliminate PO 4 3 - .
  • PTH indirectly promotes absorption of Ca 2 + and PO 4 3 - by the intestine.
  • The primary regulator of PTH secretion is plasma concentration of free Ca 2 + .
  • Calcitonin lowers plasma Ca 2 + concentration but is not important in the normal control of Ca 2 + metabolism.
  • Vitamin D is actually a hormone that increases Ca 2 + absorption in the intestine.
  • Phosphate metabolism is controlled by the same mechanisms that regulate Ca 2 + metabolism.
  • Disorders in Ca 2 + metabolism may arise from abnormal levels of PTH or vitamin D.
  • Homeostasis: Chapter in Perspective
  • Chapter 19 Study Card
  • Review Exercises
  • 20. The Reproductive System
  • 20.1. Uniqueness of the Reproductive System
  • Unique among body systems, the reproductive system does not contribute to homeostasis but plays other roles.
  • The reproductive system includes the gonads, reproductive tract, and accessory sex glands, all of which differ in males and females.
  • Reproductive cells each contain a half set of chromosomes.
  • Gametogenesis is accomplished by meiosis, resulting in genetically unique sperm and ova.
  • 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.
  • 20.2. Male Reproductive Physiology
  • The scrotal location of the testes provides a cooler environment 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.
  • GnRH 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.
  • 20.3. Sexual Intercourse between Males and Females
  • The male sex act is characterized by erection and ejaculation.
  • Erection is accomplished by penis vasocongestion.
  • Ejaculation includes emission and expulsion.
  • Orgasm and resolution complete the sexual response cycle.
  • Volume and sperm content of the ejaculate vary.
  • The female sexual cycle is similar to the male cycle.
  • Concepts, Challenges, and Controversies Environmental “Estrogens”: Bad News for the Reproductive System
  • 20.4. Female Reproductive Physiology
  • Complex cycling characterizes female reproductive physiology.
  • The steps of gametogenesis are the same in both sexes, but the timing and outcome differ sharply.
  • The ovarian cycle consists of alternating follicular and luteal phases.
  • The follicular phase is characterized by 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.
  • Cyclic 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
  • 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 by means 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
  • Hormones secreted by the placenta play a critical role in maintaining 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.
  • Homeostasis: Chapter in Perspective
  • Chapter 20 Study Card
  • Review Exercises
  • Appendix A. A Review of Chemical Principles
  • Appendix B. Text References to Exercise Physiology