What is diastole?

What is diastole?

• A. The period of relaxation and filling of the heart
• B. The period of contraction of the heart
• C. The electrical impulses initiated in the atrium
• D. The moment the heart beats

Answer: (A)

Diastole is the phase of the cardiac cycle when the heart relaxes and the ventricles fill with blood. After the previous heartbeat, the ventricular muscles relax, pressure inside the chambers drops, and the atrioventricular valves open, allowing blood to flow from theatria into the ventricles. This filling prepares the heart for the next contraction and helps ensure the ventricles have enough preload. The other descriptions refer to the heart’s contraction (systole), the electrical activity that initiates beat generation (atrial depolarization), or a vague moment rather than a distinct phase, so they don’t capture what diastole truly is.

Diastole is the phase of the cardiac cycle when the heart relaxes and the ventricles fill with blood. After the previous heartbeat, the ventricular muscles relax, pressure inside the chambers drops, and the atrioventricular valves open, allowing blood to flow from theatria into the ventricles. This filling prepares the heart for the next contraction and helps ensure the ventricles have enough preload. The other descriptions refer to the heart’s contraction (systole), the electrical activity that initiates beat generation (atrial depolarization), or a vague moment rather than a distinct phase, so they don’t capture what diastole truly is.