Diastole

Definition

Diastole is the phase of the cardiac cycle when the heart muscles relax and allow the chambers to fill with blood. It occurs after systole, which is the contraction phase.

5 Must Know Facts For Your Next Test

1. Diastole is crucial for ensuring adequate filling of the heart chambers and subsequent cardiac output.
2. During diastole, the atrioventricular (AV) valves (tricuspid and mitral) are open, allowing blood to flow from the atria to the ventricles.
3. The duration of diastole can be affected by heart rate; a faster heart rate shortens diastolic time.
4. Coronary artery perfusion primarily occurs during diastole due to lower intra-myocardial pressure compared to systole.
5. Measurement of blood pressure includes both systolic and diastolic values; diastolic pressure reflects the minimum arterial pressure during relaxation.

Review Questions

• What happens to the heart chambers during diastole?
• How does an increased heart rate affect diastolic duration?
• Why is coronary artery perfusion more efficient during diastole?

Related terms

Systole:

The phase of the cardiac cycle when the heart muscles contract and pump blood out of the chambers.

Atrioventricular Valves: Valves located between each atrium and ventricle that open during diastole to allow blood flow into ventricles.

Cardiac Output:

The volume of blood pumped by the heart per minute, dependent on both stroke volume and heart rate.