Regulation of stroke volume and heart rate Flashcards Preview

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Flashcards in Regulation of stroke volume and heart rate Deck (12):
1

regarding stroke volume, what does starlings law state?

the energy of contraction Is proportional to the initial length of the cardiac muscle fibre

2

what is the afterload?

the load against which the muscle tries to contract

3

if the afterload increases, what will happen to the stroke volume?

increase in afterload = increase in aortic pressure = increase in TPR
therefore the ventricle will have to work harder to push the blood which will be less effective as it is using up more energy.
this results in a decrease in SV

4

afterload is set by the aortic pressure which depends on what?

TRP

5

what is the parasympathetic affect on stroke volume?

it has little effect because the vagus nerve doesn't innervate the ventricular muscle

6

does hypercalcaemia cause an increase or decrease in stroke volume?

increase

7

does ischaemia cause an increase or decrease in stroke vol?

decrease

8

does hypocalcaemia cause an increase or decrease in stroke vol?

decrease

9

how does the heart compensate for a reduction in pumping ability?

the heart will compensate by working around a greater EDV.
this however results in a lower ejection fraction and reduced exercise capacitance

10

name a type of drug which causes a decrease in stroke volume?

barbiturates

11

heart rate X stroke volume = ?

heart rate

12

why does increasing the heart rate with an electronic pacemaker cause a small increase in CO but then SV decrease?

the shortened cardiac interval cuts into the rapid filling phase
this reduces EDV which reduces pre load and therefore stroke volume