Cardiovascular Physiology

Chapter 1 OVERVIEW OF THE CIRCULATION AND BLOOD

The Circulatory System

Blood

Erythrocytes

Leukocytes

Lymphocytes

Platelets

Blood Is Divided into Groups by Antigens Located on Erythrocytes

Summary

Case 1-1

Chapter 2 EXCITATION: THE CARDIAC ACTION POTENTIAL

Cardiac Action Potentials Consist of Several Phases

The Principal Types of Cardiac Action Potentials Are the Slow and Fast Types

Ionic Basis of the Resting Potential

The Fast Response Depends Mainly on Voltage-Dependent Sodium Channels

Ionic Basis of the Slow Response

Conduction in Cardiac Fibers Depends on Local Circuit Currents

Conduction of the Fast Response

Conduction of the Slow Response

Cardiac Excitability Depends on the Activation and Inactivation of Specific Currents

Fast Response

Slow Response

Effects of Cycle Length

Summary

Case 2-1

Chapter 3 AUTOMATICITY: NATURAL EXCITATION OF THE HEART

The Heart Generates Its Own Pacemaking Activity

Sinoatrial Node

Ionic Basis of Automaticity

Overdrive Suppression

Atrial Conduction

Atrioventricular Conduction

Ventricular Conduction

An Impulse Can Travel Around a Reentry Loop

Afterdepolarizations Lead to Triggered Activity

Early Afterdepolarizations

Delayed Afterdepolarizations

Electrocardiography Displays the Spread of Cardiac Excitation

Scalar Electrocardiography

Dysrhythmias Occur Frequently and Constitute Important Clinical Problems

Altered Sinoatrial Rhythms

Atrioventricular Transmission Blocks

Premature Depolarizations

Ectopic Tachycardias

Fibrillation

Summary

Case 3-1

Chapter 4 THE CARDIAC PUMP

The Microscopic and Gross Structures of the Heart

Cardiac Muscle (myocardial) Cell Morphology

Structure of the Heart: Atria, Ventricles, and Valves

The Force of Cardiac Contraction Is Determined by Excitation-Contraction Coupling and the Initial Sarcomere Length of the Myocardial Cells

Excitation-Contraction Coupling Is Mediated by Calcium

Mechanics of Cardiac Muscle

The Sequential Contraction and Relaxation of the Atria and Ventricles Constitute the Cardiac Cycle

Ventricular Systole

Echocardiography Reveals Movement of the Ventricular Walls and of the Valves

The Two Major Heart Sounds Are Produced Mainly by Closure of the Cardiac Valves

The Pressure-Volume Relationships in the Intact Heart

Passive or Diastolic Pressure-Volume Relationship

Active or End-Systolic Pressure-Volume Relationship

Pressure and Volume during the Cardiac Cycle: The P-V Loop

Preload and Afterload during the Cardiac Cycle

Contractility

The Fick Principle Is Used to Determine Cardiac Output

Metabolism of ATP and its Relation to Mechanical Function

Fatty Acid Metabolism

Carbohydrate Metabolism

Interrelation between Fatty Acid and Carbohydrate Metabolism

Effects of plasma substrate and insulin levels

Cardiac O₂ Consumption and the Link between Ventricular Function and Cardiac Metabolism

Summary

Case 4-1

Chapter 5 REGULATION OF THE HEARTBEAT

Heart Rate is Controlled Mainly by the Autonomic Nerves

Parasympathetic Pathways

Sympathetic Pathways

Higher Centers Also Influence Cardiac Performance

Heart Rate Can Be Regulated via the Baroreceptor Reflex

The Bainbridge Reflex and Atrial Receptors Regulate Heart Rate

Respiration Induces a Common Cardiac Dysrhythmia

Activation of the Chemoreceptor Reflex Affects Heart Rate

Ventricular Receptor Reflexes Play a Minor Role in the Regulation of Heart Rate

Myocardial Performance Is Regulated by Intrinsic Mechanisms

The Frank-Starling Mechanism Is an Important Regulator of Myocardial Contraction Force

Changes in Heart Rate Affect Contractile Force

Myocardial Performance Is Regulated by Nervous and Humoral Factors

Nervous Control

Cardiac Performance Is Also Regulated by Hormonal Substances

Summary

Case 5-1

Chapter 6 HEMODYNAMICS

Velocity of the Bloodstream Depends on Blood Flow and Vascular Area

Blood Flow Depends on the Pressure Gradient

Relationship Between Pressure and Flow Depends on the Characteristics of the Conduits

Resistance to Flow

Resistances in Series and in Parallel

Flow May Be Laminar or Turbulent

Shear Stress on the Vessel Wall

Rheologic Properties of Blood

Summary

Case 6-1

Chapter 7 THE ARTERIAL SYSTEM

The Hydraulic Filter Converts Pulsatile Flow to Steady Flow

Arterial Elasticity Compensates for the Intermittent Flow Delivered by the Heart

The Arterial Blood Pressure Is Determined by Physical and Physiological Factors

Mean Arterial Pressure

Cardiac Output

Peripheral Resistance

Pulse Pressure

Stroke Volume

Arterial Compliance

Total Peripheral Resistance and Arterial Diastolic Pressure

The Pressure Curves Change in Arteries at Different Distances from the Heart

Blood Pressure Is Measured by a Sphygmomanometer in Human Patients

Summary

Case 7-1

Chapter 8 The MICROCIRCULATION AND LYMPHATICS

Functional Anatomy

Arterioles Are the Stopcocks of the Circulation

Capillaries Permit the Exchange of Water, Solutes, and Gases

The Law of Laplace Explains How Capillaries Can Withstand High Intravascular Pressures

The Endothelium Plays an Active Role in Regulating the Microcirculation

The Endothelium is at the Center of Flow-Initiated Mechanotransduction

The Endothelium Plays a Passive Role in Transcapillary Exchange

Diffusion Is the Most Important Means of Water and Solute Transfer Across the Endothelium

Diffusion of Lipid-Insoluble Molecules Is Restricted to the Pores

Lipid-Soluble Molecules Pass Directly Through the Lipid Membranes of the Endothelium and the Pores

Capillary Filtration Is Regulated by the Hydrostatic and Osmotic Forces Across the Endothelium

Balance of Hydrostatic and Osmotic Forces

The Capillary Filtration Coefficient Provides a Method to Estimate the Rate of Fluid Movement Across the Endothelium

Hypoxia-inducible factor(s) and angiogenesis

Pinocytosis Enables Large Molecules to Cross the Endothelium

The Lymphatics Return the Fluid and Solutes That Escape Through the Endothelium to the Circulating Blood

Summary

Case 8-1

Case 8-2

Chapter 9 The PERIPHERAL CIRCULATION AND ITS CONTROL

The Functions of the Heart and Large Blood Vessels

Contraction and Relaxation of Arteriolar Vascular Smooth Muscle Regulate Peripheral Blood Flow

Cytoplasmic Ca⁺⁺ Is Regulated to Control Contraction, via MLCK

Contraction Is Controlled by Excitation-Contraction Coupling and/or Pharmacomechanical Coupling

Control of Vascular Tone by Catecholamines

Control of Vascular Contraction by Other Hormones, Other Neurotransmitters, and Autocoids

Intrinsic Control of Peripheral Blood Flow

Autoregulation and the Myogenic Mechanism Tend to Keep Blood Flow Constant

The Endothelium Actively Regulates Blood Flow

Tissue Metabolic Activity Is the Main Factor in the Local Regulation of Blood Flow

Extrinsic Control of Peripheral Blood Flow Is Mediated Mainly by the Sympathetic Nervous System

Impulses That Arise in the Medulla Descend in the Sympathetic Nerves to Increase Vascular Resistance

Sympathetic Nerves Regulate the Contractile State of the Resistance and Capacitance Vessels

The Parasympathetic Nervous System Innervates Blood Vessels Only in the Cranial and Sacral Regions of the Body

Epinephrine and Norepinephrine Are the Main Humoral Factors That Affect Vascular Resistance

The Vascular Reflexes Are Responsible for Rapid Adjustments of Blood Pressure

The Peripheral Chemoreceptors Are Stimulated by Decreases in Blood Oxygen Tension and pH and by Increases in Carbon Dioxide Tension

The Central Chemoreceptors Are Sensitive to Changes in Paco₂

Other Vascular Reflexes

Balance Between Extrinsic and Intrinsic Factors in Regulation of Peripheral Blood Flow

Summary

Case 9-1

Chapter 10 CONTROL OF CARDIAC OUTPUT: COUPLING OF HEART AND BLOOD VESSELS

Factors Controlling Cardiac Output

The Cardiac Function Curve Relates Central Venous Pressure (Preload) to Cardiac Output

Preload or Filling Pressure of the Heart

Cardiac Function Curve

Factors That Change the Cardiac Function Curve

The Vascular Function Curve Relates Central Venous Pressure to Cardiac Output

Mathematical Analysis of the Vascular Function Curve

Venous Pressure Depends on Cardiac Output

Blood Volume

Venomotor Tone

Blood Reservoirs

Peripheral Resistance

Cardiac Output and Venous Return Are Closely Associated

The Heart and Vasculature Are Coupled Functionally

Myocardial Contractility

Blood Volume

Peripheral Resistance

The Right Ventricle Regulates Not Only Pulmonary Blood Flow but Also Central Venous Pressure

Heart Rate Has Ambivalent Effects on Cardiac Output

Ancillary Factors Affect the Venous System and Cardiac Output

Gravity

Muscular Activity and Venous Valves

Respiratory Activity

Artificial Respiration

Summary

Case 10-1

Chapter 11 CORONARY CIRCULATION

Functional Anatomy of the Coronary Vessels

Coronary Blood Flow Is Regulated by Physical, Neural, and Metabolic Factors

Physical Factors

Neural and Neurohumoral Factors

Metabolic Factors

Diminished Coronary Blood Flow Impairs Cardiac Function

Energy Substrate Metabolism During Ischemia

Coronary Collateral Vessels Develop in Response to Impairment of Coronary Blood Flow

Summary

Case 11-1

Chapter 12 SPECIAL CIRCULATIONS

Cutaneous Circulation

Skin Blood Flow Is Regulated Mainly by the Sympathetic Nervous System

Ambient Temperature and Body Temperature Play Important Roles in the Regulation of Skin Blood Flow

Skin Color Depends on the Volume and Flow of Blood in the Skin and on the Amount of O₂ Bound to Hemoglobin

Skeletal Muscle Circulation

Regulation of Skeletal Muscle Circulation

Cerebral Circulation

Local Factors Predominate in the Regulation of Cerebral Blood Flow

The Pulmonary and Systemic Circulations Are in Series with Each Other

Functional Anatomy

Pulmonary Hemodynamics

Regulation of the Pulmonary Circulation

The Renal Circulation Affects the Cardiac Output

Anatomy

Renal Hemodynamics

The Renal Circulation Is Regulated by Intrinsic Mechanisms

The Splanchnic Circulation Provides Blood Flow to the Gastrointestinal Tract, Liver, Spleen, and Pancreas

Intestinal Circulation

Hepatic Circulation

Fetal Circulation

Changes in the Circulatory System at Birth

Summary

Case 12-1

Case 12-2

Case 12-3

Chapter 13 INTERPLAY OF CENTRAL AND PERIPHERAL FACTORS THAT CONTROL THE CIRCULATION

Exercise

Mild to Moderate Exercise

Severe Exercise

Postexercise Recovery

Limits of Exercise Performance

Physical Training and Conditioning

Hemorrhage

Hemorrhage Evokes Compensatory and Decompensatory Effects on the Arterial Blood Pressure

The Compensatory Mechanisms Are Neural and Humoral

The Decompensatory Mechanisms Are Mainly Humoral, Cardiac, and Hematologic

The Positive and Negative Feedback Mechanisms Interact

Summary

Case 13-1

Case 13-2

Appendix A: End-of-Chapter CASE STUDY ANSWERS

Appendix B: Comprehensive Examination