Regulation of Stroke Volume and Heart rate

Question 1

sympathetic nerve activation causes release of noradrenalin and adrenaline where do they act upon

Answer 1

B-1 receptors on the SA node

Question 2

activation of the parasympathetic system causes the vagus to release Ach where does this act upon

Answer 2

muscarinic receptors on the SA node

Question 3

what is preload

Answer 3

tension put on the heart muscle BEFORE it contracts

Question 4

what is after load

Answer 4

Afterload is the load against which the muscle tries to contract

Question 5

what factors affect afterload

Answer 5

CO

TPR

Question 6

if TPR increases what will happen to SV

Answer 6

SV will decrease. As if TPR increases, aortic pressure will increase and the ventricle will have to work harder to push open the aortic valve and it will have less energy to eject blood.

Question 7

HR with an electronic pacemaker, causes a small increase in CO, but then SV decreases. Why

Answer 7

Shortened cardiac interval, at heart rates above 150 bpm, cuts into the rapid filling phase