Session 2-Control Of Cardiac Output Flashcards
Define afterload
The load the heart must eject blood against (roughly equal to aortic pressure)
Define preload
Amount the ventricles are stretched in diastole, related to end diastolic volume or central venous pressure
Define total peripheral resistance
Also called systemic vascular resistance - resistance to blood flow offered by all systemic vasculature
Which blood vessel offers the greatest resistance?
Arteriole
What does constriction of the arterioles cause?
Increased resistance which causes pressure in the capillaries and on the venous side to fall but will cause pressure on arterial side to rise
If TPR falls and CO is unchanged, what happens? (2)
1) Arterial pressure falls
2) Venous pressure increases
If TPR increases and CO is unchanged, what happens? (2)
1) Arterial pressure will increase
2) Venous pressure will fall
If CO increases and TPR is unchanged, what happens? (2)
1) Arterial pressure increases
2) Venous pressure falls
If CO decreases and TPR is unchanged, what happens? (2)
1) arterial pressure falls
2) venous pressure rises
What dilates if tissues need more blood? (2)
1) arterioles
2) precapillary sphincters
How does the heart respond to changes in central venous pressure (CVP) and arterial blood pressure (aBP)?
Intrinsic and extrinsic mechanisms
What is the equation for cardiac output?
Cardiac output = stroke volume x heart rate
Complete the sentence:
The ________ the venous pressure, the more the heart fills
Higher
What is the Frank-Starling law of the heart?
If heart fibres are stretched before contracting, they will contract harder
What happens if sarcomere length is too short?
Filament overlap interferes with contraction
