Cardiac cycle

Question 1

What is the total duration of one cardiac cycle?

What is the duration of diastole?

What is the duration of systole?

Answer 1

0. 9 seconds
1. 55 seconds
2. 35 seconds

Question 2

What is systole?

Answer 2

Contraction and ejection of blood from ventricles

Question 3

What is diastole?

Answer 3

Relaxing and filling of ventricles

Question 4

What is the pressure of left atrium during systole and diastole?

Answer 4

8-10

Question 5

What is pressure change of the left ventricle during systole and diastole?

Answer 5

120/10

Question 6

What is the pressure of the aorta during systole and diastole?

Answer 6

120/80

Question 7

What is the origin of the first heart sound?

Answer 7

When the tricuspid and mitral valve close during phase 2

Question 8

What is the origin of the second heart sound?

Answer 8

Closure of the aortic and pulmonary valve during phase 5

Question 9

Describe the ECG curve during the cardiac cycle

Answer 9

Phase 1 - P wave of atrial depolarisation
Phase 2 - QRS depolarisation of the ventricles
Phase 4 - T wave of ventricular repolarisation

Question 10

Which phases of the cardiac cycle are systole?

Which are diastole?

Answer 10

Systole - 2-4

Diastole 5 - 1

Question 11

Describe the left ventricular volume over the cardiac cycle.

Answer 11

After phase 1 - End diastolic volume, final 10% of ventricle filling
After phase 2 - NO change
Phase 3 - Down as rapid ejection into aorta
Phase 4 - Small reduction
Phase 5 - Constant as all valves closed, ESV
Phase 6 - increasing as intraventricular pressure is below atrial pressure
Phase 7 - Ventricles are 90% full

Question 12

Describe left atrial pressure over the cardiac cycle

Answer 12

Phase 1 - A wave due to atrial systole, increase in pressure
Phase 2 - C wave as valves close, small increase
Phase 3 - X descent as base pulled downwards due to ventricular contraction
Phase 4 - V wave, pressure increases due to venous return
Phase 6 - Y descent as mitral valve opens to allow ventricular filling

Question 13

Describe aortic pressure over the cardiac cycle

Answer 13

Phase 3 - increases as valve opens and ventricular pressure exceeds it, ventricular contraction
Phase 4 - Down as ejection falls and repolarisation occurs
Phase 5 - Dicrotic notch caused by valve closure

Question 14

Describe left ventricular pressure over the cardiac cycle

Answer 14

Phase 2 - increases due to contraction
Phase 4 - Decreases as ejection falls and repolarisation occurs
Phase 5 - Rapid decline

Question 15

What are the 7 phases of the cardiac cycle

Answer 15

1. Atrial contraction
2. Isovolumetric contraction
3. Rapid ejection
4. Reduced ejection
5. Isovolumetric relaxation
6. Rapid filling
7. Reduced filling