Quantitative Human Physiology

Quantitative Human Physiology: An Introduction presents a course in quantitative physiology developed for undergraduate students of Biomedical Engineering at Virginia Commonwealth University. The text covers all the elements of physiology in nine units: (1) physical and chemical foundations; (2) cell physiology; (3) excitable tissue physiology; (4) neurophysiology; (5) cardiovascular physiology; (6) respiratory physiology; (7) renal physiology; (8) gastrointestinal physiology; and (9) endocrinology. The text makes extensive use of mathematics at the level of calculus and elementary differential equations. Examples and problem sets are provided to facilitate quantitative and analytic understanding, while the clinical applications scattered throughout the text illustrate the rationale behind the topics discussed. This text is written for students with no knowledge of physiology but with a solid background in calculus with elementary differential equations. The text is also useful for instructors with less time; each chapter is intended to be a single lecture and can be read in a single sitting.

• A quantitative approach that includes physical and chemical principles
• An integrated approach from first principles, integrating anatomy, molecular biology, biochemistry and physiology. Illustration program reinforces the integrated nature of physiological systems
• Pedagogically rich, including chapter objectives, chapter summaries, large number of illustrations, and short chapters suitable for single lectures
• Clinical applications relevant to the biomedical engineering student (TENS, cochlear implants, blood substitutes, etc.)
• Problem sets provide opportunity for practice and assessment throughout the course.

Undergraduate bioengineering students

Preface

Acknowledgments

UNIT 1. Physical and Chemical Foundations of Physiology

1.1. The Core Principles of Physiology

Human Physiology Is the Integrated Study of the Normal Function of the Human Body

Cells Are the Organizational Unit of Life

The Concept of Homeostasis Is a Central Theme of Physiology

The Body Consists of Causal Mechanisms That Obey the Laws of Physics and Chemistry

Evolution Is an Efficient Cause of the Human Body Working Over Long Time Scales

Living Beings Transform Energy and Matter

Function Follows Form

Coordinated Command and Control Requires Signaling at All Levels of Organization

Physiology Is a Quantitative Science

Summary

Review Questions

1.2. Physical Foundations of Physiology I

Forces Produce Flows

Conservation of Matter or Energy Leads to the Continuity Equation

Steady-State Flows Require Linear Gradients

Heat, Charge, Solute, and Volume Can Be Stored: Analogues of Capacitance

Pressure Drives Fluid Flow

Poiseuille’s Law Governs Steady-State Laminar Flow in Narrow Tubes

The Law of LaPlace Relates Pressure to Tension in Hollow Organs

Summary

Review Questions

Appendix 1.2.A1 Derivation of Poiseuille’s Law

1.3. Physical Foundations of Physiology II

Coulomb’s Law Describes Electrical Forces

The Electric Potential Is the Work per Unit Charge

The Idea of Potential Is Limited to Conservative Forces

Potential Difference Depends Only on the Initial and Final States

The Electric Field Is the Negative Gradient of the Potential

Force and Energy Are Simple Consequences of Potential

Gauss’s Law Is a Consequence of Coulomb’s Law

The Capacitance of a Parallel Plate Capacitor Depends on its Area and Plate Separation

Biological Membranes Are Electrical Capacitors

Electric Charges Move in Response to Electric Forces

Movement of Ions in Response to Electrical Forces Make a Current and a Solute Flux

The Relation Between J and C Defines an Average Velocity

Summary

Review Questions

Problem Set 1.1. Physical Foundations

1.4. Chemical Foundations of Physiology I

Atoms Contain Distributed Electrical Charges

Electron Orbitals Have Specific, Quantized Energies

Human Life Requires Relatively Few of the Chemical Elements

Atomic Orbitals Explain the Periodicity of Chemical Reactivities

Atoms Bind Together in Definite Proportions to Form Molecules

Compounds Have Characteristic Geometries and Surfaces

Single CC Bonds Can Freely Rotate

Double CC Bonds Prohibit Free Rotation

Chemical Bonds Have Bond Energies, Bond Lengths, and Bond Angles

Bond Energy Is Expressed as Enthalpy Changes

The Multiplicity of CX Bonds Produces Isomerism

Unequal Sharing Makes Polar Covalent Bonds

Water Provides an Example of a Polar Bond

Intermolecular Forces Arise from Electrostatic Interactions

Atoms Within Molecules Wiggle and Jiggle and Bonds Stretch and Bend

Summary

Review Questions

Appendix 1.4.A1 Dipole Moment

1.5. Chemical Foundations of Physiology II

Avogadro’s number Counts the Particles in a Mole

Concentration is the Amount per unit Volume

Scientific Prefixes Indicate Order of Magnitude

Dilution of Solutions Is Calculated Using Conservation of Solute

Calculation of Fluid Volumes By the Fick Dilution Principle

Chemical Reactions Have Forward and Reverse Rate Constants

The Michaelis–Menten Formulation of Enzyme Kinetics

Summary

Review Questions

Appendix 1.5.A1 Transition State Theory Explains Reaction Rates in Terms of An Activation Energy

The Activation Energy Depends on the Path

1.6. Diffusion

Fick’s First Law of Diffusion Was Proposed in Analogy to Fourier’s Law of Heat Transfer

Fick’s Second Law of Diffusion Follows from the Continuity Equation and Fick’s First Law

Fick’s Second Law Can Be Derived from the One-Dimensional Random Walk

The Time for One-Dimensional Diffusion Increases with the Square of Distance

Diffusion Coefficients in Cells Are Less than the Free Diffusion Coefficient in Water

External Forces Can Move Particles and Alter the Diffusive Flux

The Stokes–Einstein Equation Relates the Diffusion Coefficient to Molecular Size

Summary

Review Questions

1.7. Electrochemical Potential and Free Energy

Diffusive and Electrical Forces Can Be Unified in the Electrochemical Potential

The Overall Force That Drives Flux Is the Negative Gradient of the Electrochemical Potential

The Electrochemical Potential Is the Gibbs Free Energy Per Mole

The Sign of ΔG Determines the Direction of a Reaction

Processes with ΔG>0 Can Proceed Only by Linking Them with Another Process with ΔG<0

The Large Negative Free Energy of ATP Hydrolysis Powers Many Biological Processes

Measurement of the Equilibrium Concentrations of ADP, ATP, and Pi Allows Us to Calculate ΔG0

Summary

Review Questions

Problem Set 1.2. Kinetics and Diffusion

UNIT 2. Membranes, Transport, and Metabolism

2.1. Cell Structure

For Cells, Form Follows Function

Organelles Make Up the Cell Like the Organs Make Up the Body

The Cell Membrane Marks the Limits of the Cell

The Cytosol Provides a Medium for Dissolution and Transport of Materials

The Cytoskeleton Supports the Cell and Forms a Network for Vesicular Transport

The Nucleus Is the Command Center of the Cell

Ribosomes Are the Site of Protein Synthesis

The ER Is the Site of Protein and Lipid Synthesis and Processing

The Golgi Apparatus Packages Secretory Materials

The Mitochondrion Is the Powerhouse of the Cell

Lysosomes and Peroxisomes Are Bags of Enzymes

Proteasomes Degrade Marked Proteins

Cells Attach to Each Other Through a Variety of Junctions

Summary

Review Questions

Appendix 2.1.A1 Some Methods for Studying Cell Structure and Function

2.2. DNA and Protein Synthesis

DNA Makes Up the Genome

DNA Consists of Two Intertwined Sequences of Nucleotides

RNA Is Closely Related to DNA

Messenger RNA Carries the Instructions for Making Proteins

Ribosomal RNA Is Assembled in the Nucleolus from a DNA Template

Transfer RNA Covalently Binds Amino Acids and Recognizes Specific Regions of mRNA

The Genetic Code Is a System Property

Regulation of DNA Transcription Defines the Cell Type

The Histone Code Provides Another Level of Regulation of Gene Transcription

Summary

Review Questions

2.3. Protein Structure

Amino Acids Make Up Proteins

Hydrophobic Interactions Can Be Assessed from the Partition Coefficient

Peptide Bonds Link Amino Acids Together in Proteins

Protein Function Centers on Their Ability to Form Reactive Surfaces

There Are Four Levels of Description for Protein Structure

Posttranslational Modification Regulates and Refines Protein Structure and Function

Protein Activity Is Regulated by the Number of Molecules or by Reversible Activation/Inactivation

Summary

Review Questions

2.4. Biological Membranes

Biological Membranes Surround Most Intracellular Organelles

Biological Membranes Consist of a Lipid Bilayer Core with Embedded Proteins and Carbohydrate Coats

Organic Solvents Can Extract Lipids from Membranes

Biological Membranes Contain Mostly Phospholipids

Phospholipids Contain Fatty Acyl Chains, Glycerol, Phosphate, and a Hydrophilic Group

Other Lipid Components of Membranes Include Cardiolipin, Sphingolipids, and Cholesterol

Phospholipids in Water Self-Organize into Layered Structures

Surface Tension of Water Results from Asymmetric Forces at the Interface

Amphipathic Molecules Spread Over a Water Surface, Reduce Surface Tension, and Produce an Apparent Surface Pressure

Phospholipids Form Bilayer Membranes Between Two Aqueous Compartments

Lipid Bilayers Can Also Form Liposomes

Lipids Maintain Dynamic Motion within the Bilayer

Lipid Rafts Are Special Areas of Lipid and Protein Composition

Membrane Proteins Bind to Membranes with Varying Affinity

Secreted Proteins Have Special Mechanisms for Getting Inside the Endoplasmic Reticulum

Summary

Review Questions

Problem Set 2.1. Surface Tension, Membrane Structure, Microscopic Resolution, and Cell Fractionation

2.5. Passive Transport and Facilitated Diffusion

Membranes Possess a Variety of Transport Mechanisms

A Microporous Membrane Is One Model of a Passive Transport Mechanism

Dissolution in the Lipid Bilayer Is Another Model for Passive Transport

Facilitated Diffusion Uses a Membrane-Bound Carrier

Facilitated Diffusion Saturates with Increasing Solute Concentrations

Facilitated Diffusion Shows Specificity

Facilitated Diffusion Shows Competitive Inhibition

Passive Transport Occurs Spontaneously Without Input of Energy

Ions Can be Passively Transported Across Membranes by Ionophores or by Channels

Water Moves Passively Through Aquaporins

Summary

Review Questions

2.6. Active Transport

The Electrochemical Potential Difference Measures the Energetics of Ion Permeation

Active Transport Mechanisms Link Metabolic Energy to Transport of Materials

Na,K-ATPase is an Example of Primary Active Transport

Na,K-ATPase forms a Phosphorylated Intermediate

There Are Many Different Primary Active Transport Pumps

The Na–Ca Exchanger as an Example of Secondary Active Transport

Secondary Active Transport Mechanisms Are Symports or Antiports

Summary

Review Questions

2.7. Osmosis and Osmotic Pressure

The Model for Water Transport Is a Microporous Membrane

Case A: The Solute Is Very Small Compared to the Pore

Case B: The Solute Is Larger than the Pore: Osmosis

The van’t Hoff Equation Relates Osmotic Pressure to Concentration

The Osmotic Coefficient Corrects for NonIdeal Behavior of Solutions

Osmosis in a Microporous Membrane Is Caused by a Momentum Deficit within the Pores

The Flow across a Membrane Responds to the Net Hydrostatic and Osmotic Pressure

Case C: The Solute is Smaller than the Pore but is not Tiny Compared to the Pore

Solutions May Be Hypertonic or Hypotonic

Osmosis, Osmotic Pressure, and Tonicity Are Related but Distinct Concepts

Osmotic Pressure Is a Property of Solutions Related to Other Colligative Properties

Cells Behave Like Osmometers

Cells Actively Regulate their Volume through RVDs and RVIs

Summary

Review Questions

Appendix 2.7.A.1 Thermodynamic Derivation of van’t Hoff’s Law

Appendix 2.7.A2 Mechanism of Osmosis across a Microporous Membrane

Problem Set 2.2. Membrane Transport

2.8. Cell Signaling

Signaling transduces One Event into Another

Cell-to-Cell Communication Can Also Use Direct Mechanical, Electrical, or Chemical Signals

Signals Elicit a Variety of Classes of Cellular Responses

Electrical Signals and Neurotransmitters Are Fastest; Endocrine Signals Are Slowest

Voltage-Gated Ion Channels Convey Electrical Signals

Voltage-Gated Ca2+ Channels Transduce an Electrical Signal to an Intracellular Ca2+ Signal

Ligand-Gated Ion Channels Open with Chemical Signals

Heterotrimeric G-Protein-Coupled Receptors (GPCRs) Are Versatile

There Are Four Classes of G-Proteins: Gαs, Gαi/Gαo, Gαq, and Gα12/Gα13

The Response of a Cell to a Chemical Signal Depends on the Receptor and Its Effectors

Chemical Signals Can Bind to and Directly Activate Membrane-Bound Enzymes

Many Signals Alter Gene Expression

Nuclear Receptors Alter Gene Transcription

Nuclear Receptors Recruit Histone Acetylase to Unwrap the DNA from the Histones

Nuclear Receptors Recruit Transcription Factors

Other Signaling Pathways Also Regulate Gene Expression

Summary of Signaling Mechanisms

Summary

Review Questions

2.9. ATP Production I

Take a Global View of Metabolism

Energy Production and use in the Cell is Analogous to Societal Production and use of Electrical Power

Energy Production Occurs in Three Stages: Breakdown into Units, Formation of Acetyl CoA and Complete Oxidation of Acetyl CoA

Fuel Reserves are Stored in the Body Primarily in Fat Depots and Glycogen

Glucose is a Readily Available Source of Energy

Glucose Release by the Liver is Controlled by Hormones through a Second Messenger System

The Liver Exports Glucose into the Blood Because it can Dephosphorylate Glucose-1-P

A Specific Glucose Carrier Takes Glucose up into Cells

Glycolysis is a Series of Biochemical Transformations Leading from Glucose to Pyruvate

Glycolysis Generates ATP Quickly in the Absence of Oxygen

Glycolysis Requires NAD+

Gluconeogenesis Requires Reversal of Glycolysis

Summary

Review Questions

2.10. ATP Production II

Oxidation of Pyruvate Occurs in the Mitochondria via the TCA Cycle

Pyruvate Enters the Mitochondria and Is Converted to Acetyl CoA

Pyruvate Dehydrogenase Releases CO2 and Makes NADH

The TCA Cycle Is a Catalytic Cycle

The ETC Links Chemical Energy to H+ Pumping Out of the Mitochondria

Oxygen Accepts Electrons at the End of the ETC

Proton Pumping and Electron Transport Are Tightly Coupled

Oxidative Phosphorylation Couples Inward H+ Flux to ATP Synthesis

The Proton Electrochemical Gradient Provides the Energy for ATP Synthesis

NADH Forms 3 ATP Molecules; FADH2 Forms 2 ATP Molecules

ATP Can Be Produced From Cytosolic NADH

Most of the ATP Produced During Complete Glucose Oxidation Comes from Oxidative Phosphorylation

Mitochondria Have Specific Transport Mechanisms

Summary

Review Questions

2.11. ATP Production III

Fats and Proteins Contribute 60% of the Energy Content of Many Diets

Depot Fat Is Stored as Triglycerides and Broken Down to Glycerol and Fatty Acids for Energy

Glycerol Is Converted to an Intermediate of Glycolysis

Fatty Acids Are Metabolized in the Mitochondria and Peroxisomes

Beta Oxidation Cleaves Two-Carbon Pieces off Fatty Acids

The Liver Packages Substrates for Energy Production by Other Tissues

Amino Acids Can Be Used to Generate ATP

Amino Acids Are Deaminated to Enable Oxidation

Urea Is Produced During Deamination and Is Eliminated as a Waste Product

Summary

Review Questions

UNIT 3. Physiology of Excitable Cells

3.1. The Origin of the Resting Membrane Potential

Introduction

The Equilibrium Potential Arises from the Balance Between Electrical Force and Diffusion

The Equilibrium Potential for K+ Is Negative

Integration of the Nernst–Planck Electrodiffusion Equation Gives the Goldman–Hodgkin–Katz Equation

Slope Conductance and Chord Conductance Relate Ion Flows to the Net Driving Force

The Chord Conductance Equation Relates Membrane Potential to All Ion Flows

The Current Convention Is that an Outward Current Is Positive

Summary

Review Questions

Appendix 3.1.A1 Derivation of the GHK Equation

3.2. The Action Potential

Cells Use Action Potentials as Fast Signals

The Motor Neuron Has Dendrites, a Cell Body, and an Axon

Passing a Current Across the Membrane Changes the Membrane Potential

An Outward Current Hyperpolarizes the Membrane Potential

The Result of Depolarizing Stimulus of Adequate Size Is a New Phenomenon—the Action Potential

The Action Potential Is All or None

The Latency Decreases with Increasing Stimulus Strength

Threshold Is the Membrane Potential at Which an Action Potential Is Elicited 50% of the Time

The Nerve Cannot Produce a Second Excitation During the Absolute Refractory Period

The Action Potential Reverses to Positive Values, Called the Overshoot

Voltage-Dependent Changes in Ion Conductance Cause the Action Potential

Conductance Depends on the Number and State of the Channels

Patch Clamp Experiments Measure Unitary Conductances

Summary

Review Questions

Appendix 3.2.A1 The Hodgkin–Huxley Model of the Action Potential

3.3. Propagation of the Action Potential

The Action Potential Moves Along the Axon

The Velocity of Nerve Conduction Varies Directly with the Axon Diameter

The Action Potential Is Propagated by Current Moving Axially Down the Axon

The Time Course and Distance of Electrotonic Spread Depend on the Cable Properties of the Nerve

Cable Properties Define a Space Constant and a Time Constant

The Cable Properties Explain the Velocity of Action Potential Conduction

Saltatory Conduction Refers to the “Jumping” of the Current from Node to Node

The Action Potential Is Spread out Over More than One Node

Summary

Review Questions

Appendix 3.3.A1 Capacitance of a Coaxial Capacitor

Problem Set 3.1. Membrane Potential, Action Potential, and Nerve Conduction

3.4. Skeletal Muscle Mechanics

Muscles Either Shorten or Produce Force

Muscles Perform Diverse Functions

Muscles Are Classified According to Fine Structure, Neural Control, and Anatomical Arrangement

Isometric Force Is Measured While Keeping Muscle Length Constant

Muscle Force Depends on the Number of Motor Units That Are Activated

The Size Principle States that Motor Units Are Recruited in the Order of Their Size

Muscle Force Can Be Graded by the Frequency of Motor Neuron Firing

Muscle Force Depends on the Length of the Muscle

Muscle Force Varies Inversely with Muscle Velocity

Muscle Power Varies with the Load and Muscle Type

Eccentric Contractions Lengthen the Muscle and Produce More Force

Concentric, Isometric, and Eccentric Contractions Serve Different Functions

Muscle Architecture Influences Force and Velocity of the Whole Muscle

Muscles Decrease Force Upon Repeated Stimulation; This Is Fatigue

Summary

Review Questions

3.5. Contractile Mechanisms in Skeletal Muscle

Introduction

Muscle Cells Have a Highly Organized Structure

The Sliding Filament Hypothesis Explains the Length–Tension Curve

Force is Produced by an Interaction Between Thick Filament Proteins and Thin Filament Proteins

Cross-Bridges from the Thick Filament Split ATP and Generate Force

Cross-Bridge Cycling Rate Explains the Fiber Type Dependence of the Force–Velocity Curve

Force Is Transmitted Outside the Cell Through the Cytoskeleton and Special Transmembrane Proteins

Summary

Review Questions

3.6. The Neuromuscular Junction and Excitation-Contraction Coupling

Motor Neurons Are the Sole Physiological Activators of Skeletal Muscles

The Motor Neuron Receives Thousands of Inputs from Other Cells

Postsynaptic Potentials Can Be Excitatory or Inhibitory

Postsynaptic Potentials Are Graded, Spread Electrotonically, and Decay with Time

Action Potentials Originate at the Initial Segment or Axon Hillock

Motor Neurons Integrate Multiple Synaptic Inputs to Initiate Action Potentials

The Action Potential Travels Down the Axon Toward the Neuromuscular Junction

Neurotransmission at the Neuromuscular Junction Is Unidirectional

Motor Neurons Release Acetylcholine to Excite Muscles

Ca2+ Efflux Mechanisms in the Presynaptic Cell Shut Off the Ca2+ Signal

Acetylcholine Is Degraded and Then Recycled

The Action Potential on the Muscle Membrane Propagates Both Ways on the Muscle

The Muscle Fiber Converts the Action Potential into an Intracellular Ca2+ Signal

The Ca2+ during E-C Coupling Originates from the Sarcoplasmic Reticulum

Ca2+ Release from the SR and Reuptake by the SR Requires Several Proteins

Reuptake of Ca2+ by the SR Ends Contraction and Initiates Relaxation

Cross-Bridge Cycling Is Controlled by Myoplasmic [Ca2+]

Sequential SR Release and Summation of Myoplasmic [Ca2+] Explains Summation and Tetany

The Elastic Properties of the Muscle Are Responsible for the Waveform of the Twitch

Repetitive Stimulation Causes Repetitive Ca2+ Release from the SR and Wave Summation

Summary

Review Questions

3.7. Muscle Energetics, Fatigue, and Training

Muscular Activity Consumes ATP at High Rates

The Aggregate Rate and Amount of ATP Consumption Varies with the Intensity and Duration of Exercise

In Repetitive Exercise, Intensity Increases Frequency and Reduces Rest Time

In Maximum Effort, There Is No Rest Phase

Metabolic Pathways Regenerate ATP on Different Timescales and with Different Capacities

The Metabolic Pathways Used by Muscle Varies with Intensity and Duration of Exercise

At High Intensity of Exercise, Glucose and Glycogen Is the Preferred Fuel for Muscle

Muscle Fibers Differ in Their Metabolic Properties

Blood Lactate Levels Rise Progressively with Increases in Exercise Intensity

Mitochondria Import Lactic Acid, Then Metabolize it; This Forms a Carrier System for NADH Oxidation

Lactate Shuttles to the Mitochondria, Oxidative Fibers, or Liver

The “Anaerobic Threshold” Results from a Mismatch of Lactic Acid Production and Oxidation

Exercise Increases Glucose Transporters in the Muscle Sarcolemma

Fatigue Is a Transient Loss of Work Capacity Resulting from Preceding Work

Early and Rapid Strength Gains Comes from Training the Brain

Strength Training Induces Muscle Hypertrophy

Hormones Influence Muscle Size (=Strength)

Myostatin Is a Negative Regulator of the Muscle Mass

Endurance Training Uses Repetitive Movements to Tune Muscle Metabolism

Our Ability to Switch Muscle Fiber Types Is Limited

Summary

Review Questions

Problem Set 3.2. Neuromuscular Transmission, Muscle Force, and Energetics

3.8. Smooth Muscle

Smooth Muscles Show No Cross-Striations

Smooth Muscle Develops Tension More Slowly But Can Maintain Tension for a Long Time

Smooth Muscle Can Contract Tonically or Phasically

Smooth Muscles Exhibit a Variety of Electrical Activities that May or May Not Be Coupled to Force Development

Contractile Filaments in Smooth Muscle Cells Form a Lattice that Attaches to the Cell Membrane

Adjacent Smooth Muscle Cells Are Mechanically Coupled and May Be Electrically Coupled

Smooth Muscle Is Controlled by Intrinsic Activity, Nerves, and Hormones

Nerves Release Neurotransmitters Diffusely onto Smooth Muscle

Contraction in Smooth Muscle Cells Is Initiated by Increasing Intracellular [Ca2+]

Smooth Muscle Cytosolic [Ca2+] Is Heterogeneous and Controlled by Multiple Mechanisms

Smooth Muscle [Ca2+] Can Be Regulated by Chemical Signals

Force in Smooth Muscle Arises from Actin–Myosin Interaction

Myosin Light Chain Phosphorylation Regulates Smooth Muscle Force

Myosin Light Chain Phosphatase Dephosphorylates the RLC

Ca2+ Sensitization Produces Force at Lower [Ca2+] Levels

Nitric Oxide Induces Smooth Muscle Relaxation by Stimulating Guanylate Cyclase

Activation of Beta2 Receptors on Smooth Muscle Causes Relaxation by Removing Cytosolic [Ca2+]

Synopsis of Mechanisms Promoting Contraction or Relaxation of Smooth Muscle

Summary

Review Questions

UNIT 4. The Nervous System

4.1. Organization of the Nervous System

The Neuroendocrine System Controls Physiological Systems

A Central Tenet of Physiological Psychology Is That Neural Processes Completely Explain All Behavior

The New Mind–Body Problem Is How Consciousness Arises from a Material Brain

External Behavioral Responses Require Sensors, Internal Processes, and Motor Response

The Nervous System Is Divided into the Central and Peripheral Nervous System

The Brain Has Readily Identifiable Surface Features

CSF Fills the Ventricles and Cushions the Brain

The Blood-Brain Barrier Protects the Brain

Cross Sections of the Brain and Staining Reveal Internal Structures

Gray Matter Is Organized into Layers

Overall Function of the Nervous System Derives from its Component Cells

Overview of the Functions of Some Major Areas of the CNS

Summary

Review Questions

4.2. Cells, Synapses, and Neurotransmitters

Nervous System Behavior Derives from Cell Behavior

Nervous Tissue Is Composed of Neurons and Supporting Cells

Glial Cells Protect and Serve

Neurons Differ in Shapes and Size

Input Information Typically Converges on the Cell and Output Information Diverges

Chemical Synapses Are Overwhelmingly More Common

Ca2+ Signals Initiate Chemical Neurotransmission

Vesicle Fusion Uses the Same Molecular Machinery That Regulates Other Vesicle Traffic

Ca2+ Efflux Mechanisms in the Pre-Synaptic Cell Shut Off the Ca2+ Signal

Removal or Destruction of the Neurotransmitter Shuts Off the Neurotransmitter Signal

The Pre-Synaptic Terminal Recycles Neurotransmitter Vesicles

Ionotropic Receptors Are Ligand-Gated Channels; Metabotropic Receptors Are GPCR

Acetylcholine Binds to Nicotinic Receptors or Muscarinic Receptors

Catecholamines: Dopamine, Norepinephrine, and Epinephrine Derive from Tyrosine

Dopamine Couples to Gs and Gi-Coupled Receptors through D1 and D2 Receptors

Adrenergic Receptors Are Classified According to Their Pharmacology

Glutamate and Aspartate Are Excitatory Neurotransmitters

GABA Inhibits Neurons

Serotonin Exerts Multiple Effects in the PNS and CNS

Neuropeptides Are Synthesized in the Soma and Transported via Axonal Transport

Summary

Review Questions

4.3. Cutaneous Sensory Systems

Sensors Provide a Window onto Our World

Exteroreceptors Include the Five Classical Senses and the Cutaneous Senses

Interoreceptors Report on the Chemical and Physical State of the Interior of the Body

Sensory Systems Consist of the Sense Organ, the Sensory Receptors, and the Pathways to the CNS

Perception Refers to Our Awareness of a Stimulus

Long and Short Receptors Differ in Their Production of Action Potentials

Anatomical Connection Determines the Quality of a Sensory Stimulus

The Intensity of Sensory Stimuli Is Encoded by the Frequency of Sensory Receptor Firing and the Population of Active Receptors

Frequency Coding is the Basis of the Weber–Fechner Law of Psychology

Adaptation to a Stimulus Allows Sensory Neurons to Signal Position, Velocity, and Acceleration

Receptive Fields Refer to the Physical Areas at Which a Stimulus Will Excite a Receptor

Cutaneous Receptors Include Mechanoreceptors, Thermoreceptors, and Nociceptors

Somatosensory Information Is Transmitted to the Brain through the Dorsal Column Pathway

The Cutaneous Senses Map onto the Sensory Cortex

Pain and Temperature Information Travel in the Anterolateral Tract

Disorders of Sensation Can Pinpoint Damage

Pain Sensation Can Be Reduced by Somatosensory Input

The Receptive Field of Somatosensory Cortical Neurons is Often On-Center, Off-Surround

Summary

Review Questions

4.4. Spinal Reflexes

A Reflex is a Stereotyped Muscular Response to a Specific Sensory Stimulus

The Withdrawal Reflex Protects Us from Painful Stimuli

The Crossed-Extensor Reflex Usually Occurs in Association with the Withdrawal Reflex

The Myotatic Reflex Involves a Muscle Length Sensor, the Muscle Spindle

The Muscle Spindle Is a Specialized Muscle Fiber

The Myotatic Reflex Is a MonoSynaptic Reflex Between Ia Afferents and the α Motor Neuron

The Gamma Motor System Maintains Tension on the Intrafusal Fibers During Muscle Contraction

The Inverse Myotatic Reflex Involves Sensors of Muscle Force in the Tendon

The Spinal Cord Possesses Other Reflexes and Includes Locomotor Pattern Generators

The Spinal Cord Contains Descending Tracts That Control Lower Motor Neurons

All of the Inputs to the Lower Motor Neurons Form Integrated Responses

Summary

Review Questions

4.5. Balance and Control of Movement

The Nervous System Uses a Population Code and Frequency Code to Control Contractile Force

Control of Movement Entails Control of α Motoneuron Activity

The Circuitry of the Spinal Cord Provides the First Layer in a Hierarchy of Muscle Control

The Motor Nerves Are Organized by Myotomes

Spinal Reflexes Form the Basis of Motor Control

Purposeful Movements Originate in the Cerebral Cortex

The Primary Motor Cortex Has a Somatotopic Organization

Motor Activity Originates from Sensory Areas Together with Premotor Areas

Motor Control Is Hierarchical and Serial

The Basal Ganglia and Cerebellum Play Important Roles in Movement

The Substantia Nigra Sets the Balance Between the Direct and Indirect Pathways

The Cerebellum Maintains Movement Accuracy

The Sense of Balance Originates in Hair Cells in the Vestibular Apparatus

Rotation of the Head Gives Opposite Signals from the Two Vestibular Apparatuses

The Utricles and Saccules Contain Hair Cells That Respond to Static Forces of Gravity

The Afferent Sensory Neurons from the Vestibular Apparatus Project to the Vestibular Nuclei in the Medulla

Summary

Review Questions

Problem Set 4.1. Nerve Conduction

4.6. The Chemical Senses

The Chemical Senses Include Taste and Smell

Taste and Olfactory Receptors Turn Over Regularly

The Olfactory Epithelium Resides in the Roof of the Nasal Cavities

Olfactory Receptor Cells Send Axons Through the Cribriform Plate

Humans Recognize a Wide Variety of Odors but Are Often Untrained in Their Identification

The Response to Specific Odorants Is Mediated by Specific Odorant Binding Proteins

The Olfactory Receptor Cells Send Axons to Second-Order Neurons in the Olfactory Bulb

Each Glomerulus Corresponds to One Receptor That Responds to its Molecular Receptive Range

Olfactory Output Connects Directly to the Cortex in the Temporal Lobe

A Second Olfactory Output Is Through the Thalamus to the Orbitofrontal Cortex

A Third Pathway of Olfactory Sensors Is Between the Vomeronasal Organ and the Hypothalamus

The Detection Limits for Odors Can Be Low

Adaptation to Odors Involves the Central Nervous System

Some “Smells” Stimulate the Trigeminal Nerve and Not the Olfactory Nerve

Some Odorants Do Not Use Golf Linked to Odorant Binding Proteins

Humans Distinguish Among Five Primary Types of Taste Sensations

The Taste Buds Are Groups of Taste Receptors Arranged on Taste Papillae

TRCs Respond to Single Modalities

Salty Taste Has Two Mechanisms Distinguished by Their Amiloride Sensitivity

Sour Taste Depends on TRC Cytosolic pH

Sweet, Bitter, and Umami Taste Is Transduced by Three Sets of G-Protein-Coupled Receptors

The “Hot” Taste of Jalapeno Peppers Is Sensed Through Pain Receptors

Taste Receptors Project to the Cortex Through the Solitary Nucleus and the Thalamus

Summary

Review Questions

4.7. Hearing

The Human Auditory System Discriminates Among Tone, Timbre, and Intensity

The Auditory System Can Locate Sources of Noise Using Time Delays and Intensity Differences

The Ear Consists of Three Parts: the Outer Ear, Middle Ear, and Inner Ear: Each Has a Definite Function

Hair Cells of the Cochlea Respond to Deformation of Stereocilia Touching the Tectorial Membrane

Outer Hair Cells Move in Response to Efferent Stimulation and Thereby Tune the Inner Hair Cells

The Cochlea Produces a Tonotopic Mapping of Sound Frequency

Auditory Information Passes Through the Brain Stem to the Auditory Cortex

Language is Processed in Areas Near the Primary Auditory Cortex in the Left Hemisphere, but Music Is Processed in the Right Hemisphere

Perception of Pitch Is Accomplished by a Combination of Tuning and Phase Locking

The Cochlear Microphonic Shows that the Inner Hair Cells Have an AC Response That Can Keep up with Moderate Frequency Vibrations

Summary

Review Questions

Appendix 4.7.A1 The Physics of Sound

4.8. Vision

Overview of the Visual System

The Structure of the Eye Enables Focusing of Light on the Retina

The Vitreous Body Maintains Eye Shape

The Eye Focuses Light on the Retina by Refraction

The Lens Changes Shape to Focus Near Objects

Near-Sightedness and Far-Sightedness Are Problems in Focusing the Image on the Retina

Photoreceptor Cells in the Retina Transduce Light Signals

The Retina Consists of Several Layers and Begins Processing of Visual Signals

Bipolar Cells Are Off-Center or On-Center

The Output of Bipolar Cells Converge Onto On-Center and Off-Center Ganglion Cells

Signals from the Two Eyes Cross Over During the Central Visual Pathways

Some Ganglion Cells Project to Other Areas of the Brain

Additional Processing of Visual Images Occurs in the Visual Cortex

The Visual Cortex Sends Output to the Temporal and Parietal Lobes

We Still Do Not Know How We Perceive Visual Images

Summary

Review Questions

Appendix 4.8.A1 Refraction of Light and the Thin Lens Formula

Problem Set 4.2. Sensory Transduction

4.9. Autonomic Nervous System

The Autonomic Nervous System Serves a Homeostatic Function and an Adaptive Function

Autonomic Reflexes Are Fast

The Emotional State Greatly Affects Autonomic Efferent Function

Autonomic Efferent Nerves Have Two Neurons

The Sympathetic Nervous System Originates in the Thoracolumbar Spinal Cord

The Parasympathetic Nervous System Originates in Cranial and Sacral Nerves

Autonomic Reflexes Link Sensory Input to Motor Efferents

The Major Autonomic Neurotransmitters Are Acetylcholine and Norepinephrine

Parasympathetic Release of Acetylcholine Works on Muscarinic Receptors

Norepinephrine Released by Postganglionic Sympathetic Neurons Acts Through α- and β-Receptors

Autonomic Nerve Terminals Also Release Other Neurotransmitters

Effects of Autonomic Stimulation Depend on the Receptor on the Target Cell

The Pupillary Light Reflex Regulates Light Intensity Falling on the Retina: A Parasympathetic Reflex

Micturition Involves Autonomic Reflexes and Volitional Nervous Activity

Summary

Review Questions

UNIT 5. The Cardiovascular System

5.1. Overview of the Cardiovascular System and the Blood

The Circulatory System Is a Transport System

The Circulatory System Consists of the Heart, Blood Vessels, and Blood

The Circulatory System Carries Nutrients, Wastes, Chemical Signals, and Heat

The Circulation Is Necessary Because Diffusion from and to the Environment Is Too Slow

The Circulatory System Consists of the Pulmonary Circulation and Systemic Circulation

Most Circulatory Beds Are Arranged in Parallel

Pressure Drives Blood Flow Through the Vascular System

Vessels Are Characterized by a Compliance

Blood Consists of Cells Suspended in Plasma

Hemostasis Defends the Integrity of the Vascular Volume

Blood Coagulation Sits on a Knife Edge of Activation and Inhibition

Summary

Review Questions

5.2. Plasma and Red Blood Cells

Plasma Consists Mainly of Water, Electrolytes, and Proteins

Plasma Proteins and Ions Buffer Changes in Plasma pH

The Oncotic Pressure of Plasma Proteins Retains Circulatory Volume

The Erythrocyte Is the Most Abundant Cell in the Blood

Erythrocytes Contain a Lot of Hemoglobin

Hemoglobin Consists of Four Polypeptide Chains, Each with a Heme Group

Erythropoietin Controls Formation of Erythrocytes from Pluripotent Stem Cells in Bone Marrow

Phagocytes in the Reticuloendothelial System Destroy Worn Erythrocytes

Iron Recycles into New Heme

Human Blood Can Be Classified into a Small Number of Blood Types

Summary

Review Questions

5.3. White Blood Cells and Inflammation

The White Blood Cells Include Neutrophils, Eosinophils, Basophils, Monocytes, Lymphocytes, and Platelets

White Blood Cells Originate from Pluripotent Stem Cells

Neutrophils Are Phagocytes

Monocytes Leave the Circulatory System to Become Tissue Macrophages

Basophils Resemble Mast Cells

Eosinophils Are Involved in Defense of Parasitic Infections and Allergies

Lymphocytes Form a Specific Defense System

Tissue Macrophages, Monocytes, and Specialized Endothelial Cells Form the Reticuloendothelial System

Inflammation Is the Net Response of the Body to Tissue Injury

Inflammation Begins with the Release of Signaling Molecules from the Damaged Tissue

The Innate Immune Response Requires No Prior Exposure–Specificity of the Response Is Inherited in the Genome

Neutrophils and Monocytes Leave the Circulatory System by Diapedesis in Response to Chemotaxic Compounds

The Complement System Destroys Microbes that Have Attached Antibodies

Summary

Review Questions

5.4. The Heart as a Pump

The Heart Is Located in the Center of the Thoracic Cavity

The Heart Is a Muscle

Contraction of Cardiac Muscle Produces a Pressure within the Chamber

Blood is Pumped through Four Chambers

The Four Valves Are Nearly CoPlanar

Closure of the Valves Produces the Heart Sounds

Additional Turbulence Causes Heart Murmurs

Summary of the Contractile Events in the Cardiac Cycle

An Automatic Electrical System Controls the Contraction of the Heart

Summary

Review Questions

Problem Set 5.1. Blood

5.5. The Cardiac Action Potential

Different Cardiac Cells Differ in Their Resting Membrane Potential and Action Potential

SA Nodal Cells Spontaneously Generate Action Potentials Whereas Contractile Cells Have Stable Resting Membrane Potentials

Autonomic Nerves Alter the Heart Rate by Affecting the Pacemaker Potential

The Ionic Basis of the Ventricular Cardiomyocyte Action Potential

Epinephrine Enhances the L-Type Ca2+ Channels, Which Elevates the Action Potential Plateau

The Action Potential Is Conducted to Neighboring Cells through Gap Junctions in the Intercalated Disks

Summary

Review Questions

5.6. The Electrocardiogram

The ECG is the Projection of Cardiac Electrical Activity onto the Body Surface

The Heart Muscle Fibers Act as Electric Dipoles

Einthoven Idealized the Thorax as a Triangle

The Heart’s Electric Dipole Moment Varies with Time—and so Does its Recording on Leads I, II, and III

The Values of Leads I and III Can Be Used to Calculate the Electric Dipole Moment of the Heart

Atrial Depolarization Causes the P wave

Sequential Depolarization of the Ventricles Produces the QRS Complex

The Subepicardium Repolarizes before the Subendocardium, Causing an Upright T wave

The Cardiac Dipole Traces a Closed Curve during Each Heart Beat

The Largest Depolarization Defines the Mean Electrical Axis

Unipolar Leads Record the Difference between an Electrode and a Zero Electrode

Augmented Unipolar Limb Leads Use Combination of Only Two Electrodes for the Indifferent Electrode

The Einthoven Triangle is Only Approximately Valid

The Cardiac Cycle, Revisited

Summary

Review Questions

5.7. The Cellular Basis of Cardiac Contractility

Cardiac Muscle Shares Many Structural Features with Skeletal Muscle

Intercalated Disks Electrically Couple Cardiomyocytes

The Strength of Cardiac Muscle Contraction Is not Regulated by Recruitment or by Summation

Cardiac Myofibrils Have Thick and Thin Filaments and Form the Cross-Striations

Actin-Activated Myosin ATPase Activity Produces Force and Shortening

Cytoplasmic [Ca2+] Controls Actomyosin Cross-Bridge Cycling

Calcium-Induced Calcium Release Couples Excitation to Contraction in Cardiac Muscle

Reuptake of Ca2+ by the SR and SL Extrusion of Ca2+ Cause Relaxation

Mitochondria Can Take Up Ca2+

Calsequestrin Augments SR Ca2+ Uptake and Release

What Regulates Cardiac Contractility?

The Force Generally Increases with the Frequency of the Heart Beat: The Force–Frequency Relation

Sympathetic Stimulation Increases Force by Increasing the Ca2+ Transient

Parasympathetic Stimulation Opposes Sympathetic Effects (see Figure 5.7.7)

Cardiac Glycosides Increase Cardiac Contractility by Increasing the Ca2+ Transient

Cardiac Contractile Force Is Powerfully Modulated by Stretch

Summary

Review Questions

5.8. The Cardiac Function Curve

Cardiac Output Is the Flow Produced by the Heart

Stroke Volume Is Determined by Preload, Afterload, and Contractility

The Integral of the Pressure–Volume Loop Is the PV Work

Total Work of the Heart Includes Pressure, Kinetic, and Gravitational Terms

Stretch of the Heart Determines the Stroke Volume: The Frank–Starling Law of the Heart

The Ventricular Function Curve Plots Cardiac Function against Right Atrial Pressure

Increasing Preload Increases the Stroke Volume, Increasing Afterload Decreases It

Positive Inotropic Agents Shift the Cardiac Function Curve Up and to the Left

Fick’s Principle Estimates Cardiac Output from O2 Consumption

Cardiac Output can be Determined by the Indicator Dilution Method

The Thermal Dilution Method

Summary

Review Questions

Problem Set 5.2. Cardiac Work

5.9. Vascular Function

The Vascular System Distributes Cardiac Output to the Tissues

The Circulatory System Uses Four Major Physical Principles

Flow is Driven by a Pressure Difference

Compliance Describes the Relation between Pressure and Volume in the Vessels

The Heart’s Ejection of Blood into the Arterial Tree Causes the Arterial Pressure Pulse

The Pulse Pressure Depends on the Stroke Volume and Compliance of the Arteries

Diastolic Pressure Plus One-Third Pulse Pressure Estimates the Mean Arterial Pressure

Pressure and Flow Waves Propagate Down the Arterial Tree

Clinicians Use a Sphygmomanometer to Measure Blood Pressure

Blood Vessels Branch Extensively, Reducing Their Diameter but Increasing the Overall Area

The Major Pressure Drop in the Arterial Circulation Occurs in the Arterioles

Poiseuille’s Law Only Approximately Describes Flow in the Vasculature

The Ratio of ΔP to Qv Defines the Vascular Resistance

Summary

Review Questions

5.10. The Microcirculation and Solute Exchange

The Exchange Vessels Include Capillaries, Terminal Arterioles, and Venules

Ultrastructural Studies Reveal Three Distinct Types of Capillaries

Capillary Exchange Uses Passive Mechanisms

Passive Diffusion Obeys Fick’s Law of Diffusion Across Multiple Barriers

Either Flow or Diffusion Can Limit Delivery of Materials to Cells

The Interstitial Fluid Concentration Is Set by the Balance Between Consumption and Delivery

Regulation of Perfusion Regulates Solute Transfer

Some Macromolecules Cross the Capillary Wall by Transcytosis

Starling First Described the Forces That Drive Bulk Fluid Movement Across Capillaries

In Most Organs, Net Filtration Pressure Drives Fluid Out of the Capillaries at the Arteriolar End

The Lymphatics Drain the Fluid Filtered Through the Capillaries Back into the Blood

Muscle Activity Helps Pump Lymph Through the Lymphatics

Summary

Review Questions

5.11. Regulation of Perfusion

For Any Given Input Pressure, the Caliber of the Arterioles Controls Perfusion of a Tissue

Vasoconstriction Decreases Capillary Pressure

Vascular Smooth Muscle Contracts by Activation of Myosin Light Chain Kinase

Multiple Signals Regulate the Activity of MLCK and MLCP

Multiple Mechanisms Cause Vasodilation

Control of Blood Vessel Caliber Is Local (Intrinsic) and Systemic (Extrinsic)

The Myogenic Response Arises from the Contractile Response to Stretch

Endothelial Secretions Dilate Arterioles

Metabolic Products Generally Vasodilate

Paracrine Secretions Affect Vascular Caliber

The Sympathetic Nervous System Predominantly Controls the Vascular System

Circulating Hormones That Affect Vessel Caliber Include Epinephrine, Angiotensin, ANP, and Vasopressin

Summary

Review Questions

5.12. Integration of Cardiac Output and Venous Return

The Cardiovascular System Is Closed

The Cardiovascular System Can Be Simplified for Analysis

The Operating Point of the Cardiovascular System Matches Cardiac Function to Vascular Function

The Mean Systemic Pressure Normally Equals the Mean Circulatory Pressure

Filling the Empty Circulatory System Reveals Stressed and Unstressed Volumes

The Vascular Function Curve Can Be Derived from Arterial and Venous Compliances and TPR

The Experimentally Determined Vascular Function Curve Follows the Theoretical Result Only for Positive Right Atrial Pressures

Simultaneous Solution of the Cardiac Function Curve and Vascular Function Curve Defines the Steady-State Operating Point of the Cardiovascular System

Changing Arteriolar Resistance Rotates the Vascular Function Around PMS

Changes in Blood Volume Shift the Vascular Function Curve Vertically

Changes in the Cardiac Function Curve Change the Steady-State Operating Point

Strenuous Exercise Alters Multiple Parts of the Cardiovascular System

Summary

Review Questions

5.13. Regulation of Arterial Pressure

Arterial Pressure Drives Flow but Arterial Pressure also Arises from Flow

Regulation of Arterial Pressure Occurs on Three Separate Timescales Involving Three Distinct Types of Mechanisms

Baroreceptors in the Carotid Sinus and Aortic Arch Sense Blood Pressure

The Baroreflex Regulates Heart and Vasculature to Stabilize Blood Pressure

The Baroreflex Mediates Parasympathetic and Sympathetic Output from Centers Located in the Medulla

Inspiration Influences Heart Rate—The Respiratory Sinus Arrhythmia

Higher Centers Influence Blood Pressure and Heart Rate

Long-Term Regulation of Blood Volume Determines Long-Term Regulation of Blood Pressure

Sympathetic Tetralogy

Hormonal Regulation of Blood Pressure

Summary

Review Questions

Problem Set 5.3. Hemodynamics and Microcirculation

UNIT 6. Respiratory Physiology

6.1. The Mechanics of Breathing

The Respiratory System Supplies O2 and Removes Waste CO2

Four Core Aspects of Respiratory Physiology

Air Flows Through an Extensive Airway System That Filters, Warms, and Humidifies the Air

Gas Flows in Response to Pressure Differences

Changes in Lung Volumes Produce the Pressure Differences That Drive Air Movement

Skeletal Muscles Power Inspiration

Resting Expiration Is Passive; Abdominal Muscles Aid in Forceful Expiration

The Pleura and the Pleural Fluid Join the Lungs to the Chest Wall

Compliance Measures the Ease of Expanding the Lungs

The Compliance and Recoil Tendency of the Lung Is Produced by Elastic Fibers and by Surface Tension

The Law of Laplace Predicts Alveolar Instability

Pulmonary Surfactant Lowers the Surface Tension in the Alveoli

The Lungs and Chest Wall Interact to Produce the Pressures That Drive Ventilation

Breaking the Seal on the Intrapleural Space Collapses the Lungs

Airway Resistance Partly Determines Dynamic Pressures

Summary

Review Questions

6.2. Lung Volumes and Airway Resistance

Spirometers Measure Lung Volumes and Allow Identification of Several Lung Volumes and Lung Capacities

Lung Capacities Are Combinations of Two or More Lung Volumes

Lung Volumes and Capacities Vary Mainly with Body Size

Pulmonary Ventilation Is the Product of Respiratory Rate and TV

During Exercise, Pulmonary Ventilation Increases Due to Increased RR and TV

The Maximum Voluntary Ventilation Exceeds Pulmonary Ventilation During Exercise

Spirometry Also Provides a Clinically Useful Measure of Airway Resistance

Airway Resistance Depends on Whether Airflow Is Laminar or Turbulent

The Poiseuille Equation Derived for Right Cylinders Does Not Model the Complicated Airways

Airway Resistance Is the Slope Between ΔP and QV

Turbulent and Laminar Flow Result in Resistances That Occur in Series and Add

Airway Resistance Depends on Lung Volume

Dynamic Compression of the Airways During Forceful Expiration Limits Airflow

Airway Resistance Is Modified by Smooth Muscle Contraction of the Airways

Summary

Review Questions

6.3. Gas Exchange in the Lungs

The Respiratory System Exchanges Blood Gases with Atmospheric Gases

The Partial Pressure of a Gas Is its Mole Fraction Times the Total Pressure

The Vapor Pressure Is the Partial Pressure of Water in the Gas Phase That Is in Equilibrium with Liquid Water

The Vapor Pressure at Body Temperature is 47 mmHg

Henry’s Law Describes the Dissolution of Gases in Water

Conversion of Partial Pressures and Volumes at STPD to Those at BTPS

Gases Diffuse Across the Alveolar Membrane Passively

The Diffusing Capacity Is the Flow Per Unit Partial Pressure

The Anatomic Dead Space Reduces the Volume of Inspired Air That Exchanges with the Blood

Physiologic Dead Space Is Larger than the Anatomic Dead Space

The Rate of CO2 Production Allows Calculation of Alveolar Ventilation

The Alveolar Gas Equation Allows Calculation of

Blood Is in the Lungs for Less than a Second—But That Is Long Enough to Equilibrate the Gases

Blood Flow to the Lung Varies with Position with Respect to Gravity

Regulation of the Pulmonary Circulation Helps Restore the Ventilation/Perfusion Ratio

Summary

Review Questions

Appendix 6.3.A1 Derivation of the Steady-State Gas Exchange Equations

Appendix 6.3.A2 Conversion of Partial Pressures and Volumes Between STPD and BTPS

Problem Set 6.1. Airway Resistance and Alveolar Gas Exchange

6.4. Oxygen and Carbon Dioxide Transport

Dissolved Oxygen Content of Blood Is Small

Most Oxygen in Blood Is Bound to Hemoglobin

Oxygen Consumption Can Be Calculated by Blood Flow Times the A–V Difference in Oxygen

Oxygen Consumption Can Be Calculated from the Difference between O2 Inspired and O2 Expired

O2 Diffuses from Blood to the Interstitial Fluids and Then to the Cells

Hemoglobin Delivers Oxygen to the Tissues

Myoglobin Stores O2 in Oxidative Muscle and May Enhance Diffusion

Shift of the O2 Dissociation Curve to the Right Helps Deliver O2 to Exercising Muscles

Increased O2 Delivery in Exercise Is Caused by Increased Blood Flow and Shorter Diffusion

Dissolved CO2 Accounts for a Small Fraction of Blood CO2 Transport

Most CO2 Is Carried in the Blood as HCO3−

Carbaminohemoglobin Accounts for a Small Fraction of Transported CO2

Summary

Review Questions

6.5. Acid–Base Physiology I

pH Is a Monotonically Decreasing Function of [H+]

Plasma pH is Maintained within Narrow Limits

The Body Uses Chemical Buffers, the Respiratory System, and the Renal System to Regulate pH

Chemical Buffers Absorb or Desorb H+ According to the Law of Mass Action

The Isohydric Principle States that All Buffers in a Solution Are in Equilibrium with the Same [H+]

Expressing [H2CO3] in Terms of PCO2 Makes the Henderson–Hasselbalch Equation More Useful

The Respiratory System Regulates pH by Adjusting Plasma PCO2

Hypoventilation in Response to Alkalosis is Called Respiratory Compensation of Alkalosis

Hyperventilation in Response to Acidosis is Called Respiratory Compensation of Acidosis

Respiratory Acidosis and Respiratory Alkalosis

The pH–HCO3− Diagram Depicts Acid–Base Balance Graphically

Summary

Review Questions

6.6. Control of Ventilation

Nerves Regulate Breathing

Control of Breathing Involves Voluntary and Involuntary Components

The Brain stem Contains a Pontine Respiratory Group in the Pons, an Apneustic Center in the Lower Pons, and Dorsal and Ventral Respiratory Groups in the Medulla

The DRG Receives a Variety of Inputs and Excites Inspiratory Motor neurons

The VRG Contains Both I and E Neurons

Despite Progress, the Neural Mechanism of the Respiratory Pattern Remains Unknown

Peripheral Chemosensors Modulate Respiration in Response to Changes in PaO2, PaCO2, and pH

Peripheral Arterial Chemosensors Increase Firing Rates with Increased PaCO2, Decreased pH, and Decreased PaO2

Peripheral Chemosensors for PaO2 are More Important than those for PaCO2

The Ventilatory Response to Increased Chemoreceptor Firing Rate Is Increased Ventilation

Central Chemosensors Provide the Major Response to Changes in PaCO2

The Brain Adjusts the [HCO3−] of the CSF

Ventilatory Drive Increases by Integrated Response to Elevated PaCO2, Metabolic Acidosis, or Hypoxia

Airway and Lung Mechanoreceptors Alter Breathing Patterns

Increased Respiration during Exercise May be Neural and May Involve Learning

Summary

Review Questions

Problem Set 6.2. Gas Transport and pH Disturbances

UNIT 7. Renal Physiology

7.1. Body Fluid Compartments

Fick’s Dilution Principle Allows Determination of Body Fluid Compartments

Inulin Marks the Extracellular Fluid; Evans’ Blue Dye Marks Plasma

The Main Fluid Compartments Are the Intracellular Compartment, the Interstitial Compartment, and the Plasma

The TBW Varies with Body Composition

Water Composition of the LBM Varies with Age and Sex

The Fluid Compartments Correspond to Anatomic Compartments

Body Fluids Obey the Principle of Macroscopic Electroneutrality

The Gibbs–Donnan Equilibrium Arises from Unequal Distribution of Imperant Ions

Changes of Plasma Volume and Composition Transfer to all Fluid Compartments

Darrow–Yannet Diagrams Depict Fluid Compartment Composition and Volume

The Kidneys Regulate Body Fluid Volume and Composition by Acting on the Plasma

Summary

Review Questions

7.2. Functional Anatomy of the Kidneys and Overview of Kidney Function

Function Follows form in Functional Units Called Nephrons

The Paired Kidneys Have an Enormous Blood Supply and Drain Urine into the Bladder through the Ureters

Intermediate Level of Kidney Structure Reveals Functional Areas

The Renal Arteries Arise from the Abdominal Aorta

The Functional Unit of the Kidney, the Nephron, Participates in all Elementary Renal Processes

The Nephron Is a Tubule with Functionally and Microscopically Distinct Regions

The Juxtaglomerular Apparatus Produces Renin

Nonexcretory Functions of the Kidney

Summary

Review Questions

7.3. Glomerular Filtration

Morphological Studies First Led to the Idea of Glomerular Filtration

Micropuncture Studies Showed That the Fluid in Bowman’s Space Is an Ultrafiltrate

Tubular Reabsorption Explains the Lack of Nutrients in the Final Urine

Tubular Secretion Adds Material to the Ultrafiltrate

The Three Elementary Nephron Processes Are Ultrafiltration, Reabsorption, and Secretion

The Clearance of Inulin Provides an Estimate of the Glomerular Filtration Rate

The Clearance of Para Amino Hippuric Acid Allows Estimation of Renal Plasma Flow

The Clearance of a Substance Depends on How It Is Handled by the Kidney

Glomerular Filtration Is Like a Leaky Hose; about 20% of the Plasma Constituents End Up in the Filtrate

Multiple Structures Contribute to the Selectivity of the Glomerular Filtrate

The Endothelial Cell Layer Retains the Cellular Elements of Blood

The Basement Membrane Excludes Some Proteins

The Slit Membrane Retains Proteins 70 kDa or Larger

The Sieving Coefficient Depends Mainly on the Slit Diaphragm

The Glomerulus Selectively Excludes Proteins Based on Size and Charge

The Starling Forces Drive Ultrafiltration

Summary

Review Questions

Problem Set 7.1. Fluid Volumes, Glomerular Filtration, and Clearance

7.4. Tubular Reabsorption and Secretion

The Filtered Load of Water and Valuable Nutrients Is Enormous

The Renal Titration Curve of Inulin Is Linear

The Renal Titration of Glucose Shows Reabsorption and Saturation Kinetics

Saturation Kinetics and Nephron Heterogeneity Causes Splay

High Plasma Glucose in Diabetes Mellitus Causes Glucose Excretion

The Kidneys Help Regulate Plasma Phosphate

Renal Titration Curve of PAH Shows Secretion

The Meaning of the Clearance Depends on the Renal Handling

Endogenous Creatinine Clearance Approximates the GFR

Plasma Creatinine Concentration Alone Indicates the GFR

(TF/P)inulin Marks Water Reabsorption

The Double Ratio (TF/P)x/(TF/P)inulin is the Fraction of the Filtered Load of x Remaining

Micropuncture Studies Show that the Proximal Tubule Reabsorbs Two-Thirds of the Ultrafiltrate

The Proximal Convoluted Tubule Contains Many Transport Mechanisms

Absorption of Water and Salt across the Late Proximal Tubule

Summary

Review Questions

7.5. Mechanism of Concentration and Dilution of Urine

Life on Dry Land Struggles Against Desiccation

Control of Urine Concentration Uses an Osmotic Gradient and Regulated Water Permeability

Tubular Transport Mechanisms Differ Along the Length of the Nephron

The Vasa Recta Are Counter-Current Exchangers

Urea Contributes to the Osmotic Gradient in the Inner Medulla

Transport by the Vasa Recta Is Essential to the Operation of the Loop of Henle

Increased Solute Loads in the Distal Nephron Produce an Osmotic Diuresis

ADH Controls Distal Nephron Permeability

Summary

Review Questions

7.6. Regulation of Fluid and Electrolyte Balance

Regulation of Glomerular Filtration Rate Affects Urine Output

RBF and GFR Exhibit Autoregulation

The Nephron Adjusts Reabsorption of Water and Salt to Match Changes in the GFR

Water Balance in the Body Is Mediated by Antidiuretic Hormone

ADH Secretion by the Brain Is Increased by Hypovolemia and Hyperosmolarity

ADH Increases Water Permeability of the Distal Nephron

The ADH-Renal System Forms Negative Feedback Loops

Regulation of Na+ Balance Involves the Renin–Angiotensin–Aldosterone System

Atrial Natriuretic Peptide and Endogenous Digitalis-Like Substance Increases Na+ Excretion in Hypervolemia

The Integrated Response to Decreased Blood Volume

Integrated Response to Increased Na+ Load or Volume Expansion

Summary

Review Questions

7.7. Renal Component of Acid–Base Balance

The Kidneys Eliminate the Acid Produced from Metabolism

The Body Uses Chemical Buffers, the Respiratory System, and the Renal System to Regulate pH

Acid Excretion by the Tubule Adjusts Blood pH

The Kidney Links Acid Secretion to HCO3− Appearance in Plasma

Secreted Acid Reclaims HCO3− or Combines with Titratable Acid or Ammonium

Ammonia Does not Show up as Titratable Acid because its pK is too High

New HCO3− Formed Is the Sum of Titratable Acid and NH4+ Minus the Excreted HCO3−

Ammonium Originates from Amino Acids in Proximal Tubule Cells

The Thick Ascending Limb Secretes Acid, Reabsorbs Bicarbonate and Ammonium

Ion Transport in the Distal Nephron and Collecting Duct Show Reciprocal Relations between K+ and H+ Secretion and HCO3− and Cl− Secretion

Tubular pH and Cellular Regulate HCO3− Reabsorption and H+ Secretion

Excretion of NH4+ Increases with Chronic Acidosis

The Kidneys Compensate for Respiratory Acidosis by Increasing [HCO3−]

The Kidneys Compensate for Respiratory Alkalosis by Decreasing [HCO3−]

The Overall Response to Metabolic Acidosis Involves Both Lungs and Kidneys

The Overall Response to Metabolic Alkalosis Involves Both Lungs and Kidneys

The Overall Picture

Summary

Review Questions

Problem Set 7.2. Fluid and Electrolyte Balance and Acid–Base Balance

UNIT 8. Gastrointestinal Physiology

8.1. Mouth and Esophagus

The Gastrointestinal System Secures Nutrients for Maintenance, Movement, and Growth

The Gastrointestinal System Is a Tube Running from Mouth to Anus

The Gastrointestinal System Propels Material between Defined Areas Demarcated by Sphincters

The Liver and Pancreas Secrete Materials into the Intestine to Aid Digestion and Absorption

Chewing Begins Digestion

Chewing Has Multiple Purposes

Saliva Moistens, Lubricates, Digests, and Protects

Salivary Glands Produce an Isotonic Fluid that Is Subsequently Modified

Saliva Composition Depends on the Flow Rate

Parasympathetic Stimulation Results in High-Volume, Watery Saliva

Na+ and Cl− are Reabsorbed in the Salivary Ducts, and K+ and HCO3− are Secreted

The Salivary Nuclei of the Medulla Control Salivation

A Swallowing Center in the Medulla Orchestrates Swallowing

Swallowing Is a Complex Sequence of Events

Swallowing Consists of a Pharyngeal Phase and an Esophageal Phase

The Esophagus Contains an Inner Circular Smooth Muscle Layer and an Outer Longitudinal Smooth Muscle Layer

The Gut Contains Two Ganglionic Plexuses of Nerve Cells, the Body’s “Little Brain”

The LES Must Relax for Food to Enter the Stomach

Summary

Review Questions

8.2. The Stomach

The Stomach Stores Food and Releases it Gradually to the Small Intestine

The Stomach Has Distinct Regions

Extrinsic and Intrinsic Nerves Control Gastric Motility

The Orad Stomach Relaxes to Accommodate Large Meals

Pacemaker Cells along the Greater Curvature Determine Stomach Motility after a Meal

Gastric Contractions Result in Propulsion, Grinding, or Retropulsion of Stomach Contents

Stomach and Duodenal Contents Regulate Stomach Emptying

Nerves and GI Hormones Alter Stomach Emptying

The Migrating Motility Complex Clears the Stomach and Intestine during Fasting

The Stomach Secretes HCl, Pepsinogen, Mucus, Gastric Lipase, and Intrinsic Factor

Acid Secretion Is Regulated in Three Phases: The Cephalic Phase, Gastric Phase, and Intestinal Phase

The Surface Membrane H+-K+-ATPase, or Proton Pump, Actively Secretes HCl

Summary

Review Questions

8.3. Intestinal and Colonic Motility

The Small Intestine Consists of Duodenum, Jejunum, and Ileum

The Small Intestine Modulates Gastric Emptying

Intrinsic Innervation of the Intestine Consists of the Myenteric Plexus, Submucosal Plexus, and the Interstitial Cells of Cajal

Extrinsic Innervation of the Gut Arises from Parasympathetic and Sympathetic Nerves

Slow Wave Activity Forms the Basis of Intestinal Smooth Muscle Contraction

Intestinal Motility Has Several Different Patterns: Segmentations, Peristalsis, migrating motor complex or migrating myoelectric complex, and Reverse Peristalsis

The Ileocecal Sphincter Prevents Reflux of Colonic Contents into the Ileum

The Large Intestine or Colon Has Several Anatomic Regions

Colonic Motility Shows Several Distinct Patterns

Local and Extrinsic Nervous Innervation Controls Ileal and Colonic Motility

Defecation Involves Voluntary and Involuntary Muscles

Vomiting Removes Potentially Dangerous Material from the Gut

Vomiting Is a Complicated Programmed Event

Summary

Review Questions

8.4. Pancreatic and Biliary Secretion

The Exocrine Pancreas Secretes Digestive Enzymes and HCO3−

The Pancreas Secretes Four Classes of Enzyme

The Pancreas Secretes Inactive Forms of the Proteolytic Enzymes

Pancreatic Amylase Breaks Down Starches

The Pancreas Secretes a Set of Lipolytic Enzymes

The Pancreas Secretes Nucleolytic Enzymes

Pancreatic Duct Cells Secrete an Alkaline Solution

Postprandial Pancreatic Enzyme Secretion Is Regulated in Cephalic, Gastric, and Intestinal Phases

Secretin Primarily Regulates Pancreatic Duct Secretion

The Liver Produces Bile and Stores It in the Gallbladder in the Interdigestive Period

Hepatocytes Are Polarized Cells with Special Access to Plasma

Bile Consists of Bile Acids, Phospholipids, Cholesterol, Bile Pigments, Mucin, Xenochemicals, and Electrolytes

The Liver Makes and Recycles Bile Acids as an Integral Part of Biliary Secretion

The Liver Excretes Xenobiotics (Foreign Biologically Active Chemicals)

ABCG5 and ABCG8 Secrete Cholesterol into the Bile

The Gallbladder Stores and Concentrates Bile and Releases It during Digestion

The Bile Duct Cells Secrete a HCO3−-Rich Solution Much Like Pancreatic Duct Cells

Summary

Review Questions

8.5. Digestion and Absorption of the Macronutrients

The Intestine Increases Its Surface Area by Folds upon Folds

The Intestinal Lining Continuously Renews Itself

Protein Digestion Occurs in a Gastric Phase and an Intestinal Phase

Specific Carriers Move Amino Acids across the Brush Border and BasoLateral Membranes

The Intestinal Peptide Transporter Has Broad Specificity and Cotransports H+

Distinct Carriers Transport Amino Acids across the Basolateral Membrane

Carbohydrates Are Mainly Digested in the Small Intestine

Indigestible Carbohydrates Make Up Part of Dietary Fiber

The Brush Border Completes Starch Digestion

Glucose, Fructose, and Galactose Absorption is Carrier Mediated

Lipid Digestion Begins with Emulsification

Most Lipolytic Activity Occurs in the Small Intestine

Hydrolysis Products of Lipids Are Absorbed and Then Repackaged into Lipoproteins

Bile Acids Are Absorbed in the Terminal Ileum

Summary

Review Questions

8.6. Energy Balance and Regulation of Food Intake

Early Studies on Energy Balance Used Calorimeters

“The Energy Content of Food” Is Its Heat of Combustion

Measurement of Energy Expenditure by Indirect Calorimetry

Indirect Calorimetry and Urinary Nitrogen Allows Estimation of Catabolism of Macronutrients

Energy Expenditure Consists of Basal Metabolism Plus Activity Increment

Empirical Formulas for BMR

Eating Food Increases Metabolism

Activity Adds the Greatest Increment to Metabolism

The Body Homeostatically Regulates Its Weight

The Central Nervous System Regulates Feeding Behavior

Early Studies Showed That the Hypothalamus Drives Feeding Behavior

The Simplistic Early View Is Supplanted by a Picture of Multiple Centers and Multiple Signals

Short-Term Signals Limit the Size of Meals: They Are Satiety Signals

Long-Term Signals Maintain Body Composition: They Are Adiposity Signals

Integrated Mechanism of Food Intake Regulation

Summary

Review Questions

Problem Set 8.1. Energy Balance

UNIT 9. Endocrine Physiology

9.1. General Principles of Endocrinology

Endocrine Glands Release Signaling Molecules into the Blood

Modern Definitions of Hormone Include Local and Distant Effects and Integration of the Endocrine and Neural Systems of Control

The Neural System Provides Fast, Short-Lived Control; Endocrine Control Is Slower and Longer Lasting

Hormones Can Be Classified by Their Chemical Structure and Source

Polypeptide Hormones Are Typically Synthesized as Larger Precursors

Steroid Hormones Are Metabolized from Cholesterol and Are Not Stored

Blood Carries Hormones in Either Free or Bound Forms

Only Target Cells with Receptors to the Hormone Respond to the Hormone

Dose–Response Curves Derive from the Kinetics of Hormone Binding and Post-Receptor Events

Dose–Response Curves Can Be “Upregulated” or “Downregulated”

The Half-Life and Metabolic Clearance Rate Quantitatively Describe Hormone Metabolism

The MCR Is Inversely Related to the Half-Life

A Variety of Techniques Can Measure Hormone Levels

Summary

Review Questions

Appendix 9.1.A1 Analysis of Ligand Binding

9.2. Hypothalamus and Pituitary Gland

The Pituitary Gland Lies Below the Brain and Connects to the Hypothalamus by a Narrow Stalk

Cells in the Hypothalamus Synthesize ADH and Oxytocin and Secrete them in the Posterior Pituitary

Oxytocin and ADH are Chains of 9 Amino Acids

Oxytocin Contracts the Uterus and Myoepithelial Cells of Alveoli Cells in the Breast

Increased Plasma Osmolarity and Decreased Blood Volume Stimulate ADH Release

The Hypothalamus Controls Release of Hormones from the Anterior Pituitary

Multiple Signals Produces Pulsatile Release of GH

The Complicated GH Secretion Pattern Is Produced by Complicated Neuronal Circuits

GH Mediates Some of Its Effects Through Increased IGF-I

Summary

Review Questions

9.3. The Thyroid Gland

The Thyroid Gland Is One of the Largest Endrocrine Glands

The Thyroid Gland Consists of Thousands of Follicles that Store Thyroglobulin

The Thyroid Follicle Secretes Thyroxine and Triiodothyronine

Follicular Cells Secrete Thyroglobulin Precursor into the Follicle

Synthesis of Thyroxine Requires Four Steps

Follicular Cells Proteolyze Thyroglobulin to Release T4 and T3

TSH Regulates State of the Thyroid Gland

The Hypothalamus Partly Controls TSH Release

T4 and T3 Inhibit Secretion of TSH

Almost all Circulating T4 and T3 Are Bound to Plasma Proteins

The Tissues Metabolize T4 to T3 and rT3; T3 is the Active Metabolite

T3 Alters Gene Expression

Thyroid Hormone Plays A Crucial Role in Growth and Development and in General Metabolism

Hypothyroidism Refers to Reduced Circulating Levels of T4 and T3

The Clinical Symptoms of Hypothyroidism Are Manifold

The Most Important Clinical Abnormality of Hyperthyroidism is Graves’ Disease

Summary

Review Questions

9.4. The Endocrine Pancreas and Control of Blood Glucose

The Pancreas Has Both Exocrine and Endocrine Functions

β Cells Synthesize Insulin as a Prohormone and Secrete Insulin and C peptide 1:1

High Plasma Glucose Stimulates Insulin Secretion

Glucagon, GLP-1, and GIP Stimulate Insulin Secretion; Somatostatin Inhibits it

Parasympathetic Stimulation Increases Insulin Secretion; Sympathetic Stimulation Inhibits It

Amino Acids Stimulate Insulin Secretion

Sulfonylureas Close the KATP Channel and Thereby Increase Insulin Secretion

Insulin Release Is Pulsatile

Insulin Phosphorylates Insulin Receptor Substrates via a Tyrosine Kinase

Low Glucose Stimulates Glucagon Release from α Cells in the Islets of Langerhans

Glucagon Stimulates Liver Glycogenolysis through a Gs and Gq Mechanism

Blood Glucose Is Maintained Between 70 and 110 mg% in the Face of Constant Depletion

Plasma Glucose Concentrations Are Maintained by Absorption, Glycogenolysis, and Gluconeogenesis

Multiple Hormones and Nerves Control Glucose Flux

Exercise Has an Insulin-Like Effect

Summary

Review Questions

9.5. The Adrenal Cortex

The Adrenal Glands Lie Atop the Kidneys, Are Richly Vascularized, and Secrete Many Hormones

Steroid Hormones Derive from Cholesterol

The Pituitary–Hypothalamus Axis Controls Adrenal Function through ACTH

ACTH Increases Adrenal Cortical Steroid Secretion

Cortisol Binding Protein Carries Glucocorticoids in Blood

Cortisol Affects Target Cells through Regulation of Transcription

Cortisol Affects Many Body Functions

The Zona Glomerulosa Makes Aldosterone in Response to Angiotensin II, ACTH and K+

Angiotensin II Exerts Multiple Effects

Aldosterone Increases Na+ Reabsorption and K+ Secretion by Genomic and Nongenomic Mechanisms

Summary

Review Questions

9.6. The Adrenal Medulla and Integration of Metabolic Control

The Adrenal Medulla Is Part of the Sympathetic Nervous System

Epinephrine Derives from Tyrosine

Catecholamines Are Released in Response to Sympathetic Stimulation

Catecholamines Are Degraded Rapidly

Actions of Catecholamines Are Mediated by Adrenergic Receptor Types

The Effects of Catecholamines Are to Prepare the Body for “Fight or Flight”

Integration of Metabolic Control

Summary

Review Questions

9.7. Calcium and Phosphorus Homeostasis I

Calcium Homeostasis Is Required for Health

About Half of Plasma Calcium Is Free: The Other Half Is Complexed or Bound to Plasma Proteins

Failure to Regulate Plasma [Ca2+] Causes System Malfunction

Plasma Ca2+ Homeostasis Results from a Balance of Sources and Sinks

Plasma Ca2+ Homeostasis Is Linked to P homeostasis

Plasma Pi Is Present in Multiple Ionized Forms

Plasma [Pi] Is Set by a Balance Between Sources and Sinks

Overall Ca2+ and Pi Homeostasis Is Controlled by Three Hormones Acting on Three Target Tissues

Hypocalcemia Stimulates PTH Secretion

PTH Secretion Is an Example of Derivative Control

PTH Is Destroyed Rapidly After Secretion

PTH Defends Against Hypocalcemia by Actions on Bone and Kidney

CT Is Secreted in Response to Hypercalcemia and Gastrointestinal Hormones

CT Tends to Lower Plasma [Ca2+]

“Vitamin D” Is a Hormone, not a Vitamin, Synthesized in the Skin

Vitamin D Does not Fit Standard Definitions of Either Vitamin or Hormone

The Liver Activates Vitamin D by 25-Hydroxylation: The Kidney Activates It by 1-Hydroxylation

Vitamin D Inactivation Begins with 24-Hydroxylation

PTH Controls Metabolism of Vitamin D

Vitamin D Has Two Forms of Equal Potency in Humans

25(OH)2-D Is the Major Circulating Form of Vitamin D

Vitamin D Maintains Conditions for Bone Mineralization

Summary

Review Questions

9.8. Calcium and Phosphorus Homeostasis II

The Skeleton Gives Us Form and Support

Osteoblasts Are Surface Cells That Lay Down the Organic Matrix of Bone

Osteocytes are Embedded Deep within Bone

Osteoclasts Destroy the Organic Matrix of Bone and Release Both Ca2+ and Pi

Bone Is Constantly Being Remodeled

Osteoblasts Make Osteoid and Signal Bone Resorption

Osteoclasts Resorb Bone

Calcitonin Shuts Off Osteoclast Resorption

Summary of Hormone Effects on Bone

Only 1,25(OH)2-D Directly Affects Intestinal Ca2+ and Pi Absorption

The Intestine Adapts to Diets Containing Differing Amounts of Ca2+ and Pi

Regulation of Urinary Excretion of Ca2+ and Pi Is Achieved in the Distal Nephron

The “Goals” of PTH, CT, and Vitamin D Are Distinct

Integrated Control of Plasma [Ca2+] and Pi Involves Multiple Negative Feedback Loops

Summary

Review Questions

9.9. Female Reproductive Physiology

Sexual Reproduction Costs a Lot but it is Worth the Price

The Anatomy of the Female Reproductive Tract

Overiew of Female Reproductive Function

Oogenesis Begins in the Fetus

Puberty Initiates Ovulation and Development of Secondary Sex Characteristics

LH and FSH Drive the Menstrual Cycle

Overview of Follicular Development

Cellular Aspects of Follicular Development

Ovarian Steroidogenesis Requires Two Cell Types and Two Hormones

Central Hormonal Control of the Menstrual Cycle

LH and FSH Surge Induces Ovulation

After Ovulation, the Follicle Forms the Corpus Luteum

Summary

Review Questions

9.10. Male Reproductive Physiology

Somatic Cells Divide by Mitosis; Germ Cells Divide by Meiosis

Mitosis Produces Two Daughter Cells with the Same DNA Content as the Original Cell

Meiosis Divides the Parent Genome in Half—But Crossing-Over Diversifies the Result

Reassortment of Genetic Material Arises from Two Sources: Independence of Homologous Chromosome Sorting and Crossing-Over

Testicles Produce Sperm and Testosterone

The Hypothalamus and Anterior Pituitary Control Testicular Function

Both LH and FSH Control Testicular Function

The Male Sexual Response

Summary

Review Questions

Problem Set 9.1. Ligand Binding

APPENDIX I. Important Equations

APPENDIX II. Important Physical Constants for Physiology

Glossary

Index