What is the definition of diastole in relation to the heart?

Diastole refers specifically to the phase in the cardiac cycle during which the heart muscle relaxes. This relaxation allows the chambers of the heart, particularly the ventricles, to fill with blood returned from the body and the lungs. During diastole, the pressure within the chambers drops, leading to a passive filling of blood, which prepares the heart for the next contraction or systole.

Understanding diastole is essential for grasping how the heart functions as a pump. It contrasts with contraction phases, where the heart muscle actively pumps blood out to the arteries. While filling of the ventricles and regulation of blood pressure are related concepts, they are outcomes or processes that occur as a result of diastolic function rather than the definition of diastole itself.