diastolét

Diastole is the phase of the cardiac cycle when the heart muscle relaxes and the heart chambers fill with blood. This is in contrast to systole, which is the phase when the heart muscle contracts and pumps blood out. Specifically, diastole refers to the relaxation of the ventricles, the lower chambers of the heart, which allows them to fill with blood from the atria, the upper chambers.

During diastole, the aortic and pulmonary valves close, preventing blood from flowing back into the ventricles. Simultaneously, the mitral and tricuspid valves open, allowing blood to flow from the atria into the ventricles. This filling process is crucial for the heart to be able to pump an adequate amount of blood to the body. The duration of diastole varies depending on heart rate; at slower heart rates, diastole is longer, allowing for more complete ventricular filling.

Diastolic blood pressure is the lower number in a blood pressure reading and represents the pressure in the arteries when the heart is at rest between beats, during diastole. It is an important indicator of cardiovascular health. Elevated diastolic blood pressure can be a sign of hypertension. Conversely, very low diastolic blood pressure can indicate other medical conditions. Understanding diastole is fundamental to comprehending the mechanics of the circulatory system and its role in maintaining overall health.