Regulation of Cardiac Output and Venous Return Flashcards
What is meant by preload?
volume of blod in ventricles at end of diastole
When is preload increased?
- hypervolemia
- regurgitation of cardiac valves
- heart failure
What is afterload?
the resistance the left ventricle must overcome to circulate blood
When is afterload increased?
- hypertension
- vasocontriction
When preload is increased what effect does it have on stroke volume and cardiac output?
increases both
deals with diastolic volume
When preload is decreased what effect does it have on stroke volume and cardiac output?
decreases both
deals with systolic volume
When afterload is decreased what effect does it have on stroke volume and cardiac output?
increases both
When afterload is increased what effect does it have on stroke volume and cardiac output?
both are decreased
What is cardiac output?
rate of blood entering the central venous pool of blood
What is venous return?
rate of blood entering the central venpus pool of blood
Arterial and venous pressures are affected by what?
cardiac output
Increases in cardiac output can do what do arterial and venous pressure?
- increase arterial, decrease venous
- caused by redistribution of blood voume
In myocardial damage, what does reduced cardiac output result in?
- reduced arterial pressure
- increased venous pressure
What is the cardiac function curve determined by?
- determined by cardiac components
- frank-sterling law, contractility
How does right arterial pressure affect cardiac output?
central venous pressure (indep. variable) vs cardiac output (depend. variable)
What is the vascular function curve determined by?
- determined by vascular components
- resistance, blood volume, compliances
How does cardiac output affect right atrium pressure?
central venous pressure (depend. variable) vs cardiac output (independ. variable)
If you increase sympathetic stimulation of the heart what type of ionotropic effect does it have in cardiac contractility?
postive
If you increase parasympathetic stimulation of the heart what type of ionotropic effect does it have in cardiac contractility?
negative
What is the effect of increased blood volume in circulatory blood volume?
higher cardiac output and right atrium pressure
What is the effect of decreased blood volume in circulatory blood volume?
lower cardiac output and right atrium pressure
An increase in TPR has what effect ?
- increase in afterload
- decrease in cardiac output
- reduce slope of vascular function curve
What are the baroreceptor reflex responses to hemorrhage?
- increase sympathetic outflow
- increase in heart rate, contractility, cardiac output, constriction of arterioles
- decrease in constriction of veins
What is the renin-angiotensin 2- aldosterone responses to hemorrhage?
- increase in angiotensin 2
- increase in TPR
- increase in aldosterone, Na reabsorption, blood volume
What are the capillaries responses to hemorrhage?
- decrease in hydrostatic pressure
- increase in fluid absorption
- increase in blood volume
The capillaries, baroreceptor reflex, and renin-angiotensin 2- aldosterone all lead to the result of what?
the arterial pressure returning to normal
What is the central command response to exercise?
- increase in sympathetic outflow
- decrease in parasympathetic outflow
- increase in heart rate, contractility, cardiac output
- decrease constriction of veins
What is the local response to exercise?
- increase vasodilator metabolites
- decrease TPR
Central commands and local responses lead to the result of what?
increase blood flow to skeletal muscle
