Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Diastole is the phase of the cardiac cycle when the heart muscles relax and allow the chambers to fill with blood. It alternates with systole, the phase of contraction, to ensure continuous blood circulation throughout the body.
5 Must Know Facts For Your Next Test
Diastole accounts for about two-thirds of the cardiac cycle duration.
During diastole, both atria and ventricles are in a relaxed state allowing passive filling of blood into the chambers.
The diastolic pressure is a key measurement in blood pressure readings, indicating arterial pressure during heart relaxation.
Coronary arteries primarily receive blood flow during diastole due to decreased myocardial compression.
Malfunction or abnormalities during diastole can lead to conditions like diastolic heart failure.
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Related terms
Systole: The phase of the cardiac cycle where heart muscles contract and pump blood out of the chambers.
Cardiac Cycle: The sequence of events in one complete heartbeat, including both systole and diastole.
Diastolic Pressure: The arterial pressure measured during the relaxation phase of the heart's cycle.