diastoli

Diastole is a fundamental phase of the cardiac cycle, representing the period when the heart muscle relaxes and fills with blood. This relaxation is crucial for the heart to prepare for its next contraction. During diastole, the atria and ventricles are in a state of rest. Specifically, ventricular diastole refers to the relaxation of the ventricles, allowing them to fill with blood from the atria. Simultaneously, atrial diastole occurs as the atria also relax after having pumped blood into the ventricles. The valves within the heart play a critical role during diastole. The atrioventricular valves, namely the mitral and tricuspid valves, are open, permitting blood flow from the atria into the ventricles. Conversely, the semilunar valves, the aortic and pulmonary valves, are closed, preventing the backflow of blood from the aorta and pulmonary artery into the ventricles. The duration of diastole varies with heart rate; it shortens as heart rate increases, while systole (the contraction phase) shortens to a lesser extent. Diastole is essential for maintaining adequate cardiac output and ensuring the efficient oxygenation of the body.