heart cycle

Question 1

what is the preload?

Answer 1

the volume of blood coming back to the heart from the venous circulation

Question 2

what is the after load?

Answer 2

the load/fprce the heart as the pump against from the systematic circulation

Question 3

how does the sympathetic pathway increase the heart rate?

Answer 3

release adrenaline which binds to beta 2 adrenoceptors

Question 4

how does the parasympathetic pathway decrease the heart rate?

Answer 4

releases acetylcholine which binds to M2muscarinic receptors.

Question 5

what happens to ventricular systole after you increase the preload?

Answer 5

there will be an increase in blood going back to the heart from the venous circulation.
so the end diastolic volume (EDV) will be increased.
there will be a greater stretch in the cardiac fibres so there will be greater force of contraction to eject the extra volume

Question 6

what happens if you have increased after load for a long period of time?

Answer 6

could lead to CVD as the increased pressure the heart has to work against means the heart does not eject all the blood in the ventricles. so there is a higher EDV than before, which is okay because the heart can eject this extra volume. BUT
if this happens over long time it can cause CVD.