2.1 Pressures, flows and volumes during cardiac cycle

Question 1

how do the heart sounds and systole/diastole relate?

Answer 1

Systole = period between S1 and S2 (contraction and ejection period) 
Diastole = period between S2 and S1 (relaxation and filling period)

Question 2

What causes the heart sounds?

Answer 2

s1: closure of mitral (TC)
S2: closure of aortic/pulmonary (typically split during inspiration)
S3: faint rumble; opening o mitral/tricuspid valve with flow murmur into ventricles
S4: flow murmur caused by atrial contraction

Question 3

what happens in valvular regurgitation?

Answer 3

failure of valve to seal properly which leas to no separation of pressure and flow in both directions

Question 4

What happens in valvular stenosis?

Answer 4

Narrowing of the open valve diameter, requires increased ventricular pressure to maintain flow through narrowed valve

Question 5

what are the 7 phases of the cardiac cycle?

Answer 5

1. Isovolumetric contraction
2. Fast ejection
3. slow ejection - until aortic valve closes
4. Isovolumetric relaxation
5. rapid ventricular filling
6. slow ventricular filling
7. atrial contraction

Question 6

When does atrial filling mainly occur?

Answer 6

systole

Question 7

What causes the P wave?

Answer 7

atrial depolarization

Question 8

What causes the QRS complex?

Answer 8

Ventricular depolarization - start of systole

Question 9

What causes the T wave

Answer 9

ventricle depolarization - end of systole