Control of cardiac output Flashcards
What is afterload
The load the heart must eject blood against. Aka aortic pressure
What is preload?
Amount ventricles are filled in diastole
What is TPR
Resistance to blood flow by systemic vasculature
What happens to aBP and CVS if TRP increases?
aBP increases and CVP decreases
What happens to aBP and CVS if TRP decreases?
aBP decreases, CVP increases
What happens to aBP and CVS if CO increases?
Higher aBP, lower CVP
What happens to aBP and CVS if CO decreases?
Lower aBP, higher CVP
What happens during exercise to increase CO?
First muscle pumping and vasoconstriction
THEN Vasodilation to decrease TPR (increase VP)
THEN higher HR and contractility by sympathetic drive
What would happen if only venous pressure increased during exercise and cardiac output did not increase?
Frank Starling curve would not move up and left
Function would only move to the top, flat part of the curve
What does increased compliance of a ventricle mean?
Ventricles pressure increases more per a given volume compared to normal.
What is a length tension curve?
Contractile force as % optimum to resting length as % optimum
More stretching, more Calcium sensitive
If sarcomeres too short, overlap of filaments interferes with contraction
What is the Frank Starling curve?
The higher the LVEDP, the higher the stroke volume (more preload)
What shifts the Frank Starling curve up and to the left?
Increased contractility
What does the frank Starling curve ensure?
Ensures equal systemic and pulmonary cardiac output so they can act in series
