Cardiac cycle Flashcards
Which phase of the cardiac cycle will never change speed? Diastole or systole?
Systole as its the contraction
To speed up heart rate, which phase would shorten- diastole or systole?
Diastole (systole will never change)
What are the phases of the cardiac cylce?
1: atrial contraction 2: isovolumetric contraction 3: rapid ejection 4: reduced ejection 5: isovolumetric relaxation 6: rapid filling 7: reduced filling
What is the first heart sound? What causes it?
‘Lub’- mitral and tricuspid valves closing
What is the second heart sound? What causes it?
‘Dub’- aortic and pulmonary valves closing
Roughly how long does diastole last for?
0.55 seconds
Roughly how long does systole last for?
0.35 seconds
How long does the AVN delay the depolarisation for? Why?
120ms. Allows time for atria to continue emptying
In which direction does the ventricle polarise?
From inside layer (endocardium to epicardium)
In which direction do the ventricles repolarise?
From outside to in (epicardium to endocardium)
Why do we need a CVS?
Because if our blood flow were just a series of pipes, blood would only go to where it is easiest to get to. (Where theres less resistance)
What is the average pressure in the right atrium?
0-4mmHg
What is the average pressure in the left atrium?
8-10mmHg
What is the average pressure in the left ventricle?
120systolic, 10 diastolic. (mmHg)
What is the average pressure in the right ventricle?
25 systolic. 4 diastolic. (mmHg)
