Cardiovascular physiology /
| Main Author: | |
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| Other Authors: | |
| Format: | Book |
| Language: | English |
| Published: |
St. Louis, MO :
Mosby,
[2001]
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| Edition: | Eighth edition. |
| Series: | Mosby physiology monograph series.
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| Subjects: |
Table of Contents:
- The circuitry
- Electrical activity of the heart
- Cardiac action potentials consist of several phases
- 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
- 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 tachycaridas
- Fibrillation
- The cardiac pump
- The gross and microscopic structures of the heart are uniquely designed for optimal function
- Myocardia cell
- The force of cardiac contraction is largely determined by the resting length of the myocardial fibers
- Excitation-contraction coupling is mediated mainly by calcium
- Preload and afterload are important in determining cardiac performance
- The cardiac chambers consist of two atria, two ventricles, and four valves
- Cardiac valves
- The pericardium is an epithelized fibrous sac that invests the heart
- The two major heart sounds are mainly produced by closure of the cardiac valves
- The sequential contraction and relaxation of the atria and ventricles constitute the cardiac cycle
- Ventricular systole
- Ventricular diastole
- The fick principle is used to determine cardiac output
- The indicator dilution technique is a useful method for measuring cardiac output
- 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
- A common cardiac dysrhythmia is induced by respiration
- Activation of the chemoreceptor reflex affects heart rate
- The 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 contractility
- 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
- Hemodynamics
- Velocity of the bloodstream depends on blood flow and vascular area
- Blood flow depends on the pressure gradient
- Relationship between the 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
- 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
- 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 why capillaries can withstand high intravascular pressures
- The endothelium plays an active role in regulating the microcirculation
- The endothelium plays a passive role in transcapillary exchange
- Diffusion is the most important means for 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 is a convenient method to estimate the rate of fluid movement across the endothelium
- Pinocytosis enables large molecules to cross the endothelium
- The lymphatics return the fluid and solutes that escape through the endothelium to the circulating blood
- The peripheral circulation and its control
- Contraction and relaxation of arteriolar vascular smooth muscle regulate peripheral blood flow
- Intrinsic (local) control of peripheral blood flow
- Autoregulation and the myogenic mechanism tend to keep blood flow constant in the face of changes in perfusion pressure
- 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 arising in the medulla descend in the sympathetic nerves to increase vascular resistance
- Sympathetic nerves regulate the contractile state of resistance and capacitance vessels
- Parasympathetic nervous system only innervates blood vessels 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 quite sensitive to changes in Paco₂
- Other vascular reflexes
- Balance between extrinsic and intrinsic factors in regulation of peripheral blood flow
- Control of cardiac output: coupling of heart and blood vessels
- 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
- Coronary circulation
- Functional anatomy of coronary vessels
- Coronary blood flow is regulated by physical, neural, and metabolic factors
- Physical factors
- Neural and neurohumoral factors
- Metabolic factors
- Cardiac oxygen consumption is a function of the work performed by the heart
- Cardiac efficiency
- Diminished coronary blood flow impairs cardiac function
- Coronary collateral vessels develop in response to impairment of coronary blood flow
- Special circulations
- Cutaneous circulation
- Skin blood flow is regulated mainly by the sympathetic nervous system
- Skin color depends on the volume and flow of blood in the skin and the amount of O₂ bound to hemoglobin
- Skeletal muscle circulation
- Regulation of skeletal muscle circulation is achieved by neural and local factors
- Cerebral circulation
- Local factors predominate over neural factors 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 accounts for about 20% of the cardiac output
- Anatomy
- Renal hemodynamics
- The renal circulation is regulated mainly by intrinsic mechanisms
- The splanchnic circulation provides blood flow to the gastrointestinal tract, liver, spleen, and pancreas
- Intestinal circulation
- Hepatic circulation
- Fetal circulation
- Several changes occur in the circulatory system at birth
- Interplay of central and peripheral factors in the control of 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 arterial blood pressure
- The compensatory mechanisms are neural and humoral
- The decompensatory mechanisms are mainly humoral, cardiac, and hematological
- The positive and negative feedback mechanisms interact.