What is the state of the semilunar and AV valves during diastole?

During diastole, the heart is in a resting state, allowing the chambers to fill with blood. The atrioventricular (AV) valves, which separate the atria from the ventricles, are open during this phase. This openness allows blood to flow from the atria into the ventricles, facilitating the filling of the ventricles before the next contraction.

Conversely, the semilunar valves, located between the ventricles and the arteries (the aorta and pulmonary artery), are closed during diastole. The closure of the semilunar valves prevents the backflow of blood into the ventricles as they fill from the atria. This arrangement of the valves during diastole is crucial for efficient filling of the heart's chambers, ensuring that enough blood is available for the subsequent contraction (systole).

This coordinated opening and closing of the valves maintain proper blood flow and pressure within the heart and the circulatory system. Thus, the condition where the semilunar valves are closed and the AV valves are open accurately describes the state of the heart during diastole.