What happens to the outflow valves during mid-diastole?

During mid-diastole, the outflow valves are closed. In the cardiac cycle, diastole is the phase when the heart relaxes and fills with blood. Specifically, mid-diastole refers to the period when the ventricles are filling with blood from the atria and the pressure within the ventricles is lower than that in the atria.

During this phase, the atrioventricular (AV) valves are open, allowing blood to flow from the atria into the ventricles. However, the outflow valves (the aortic and pulmonary valves) are designed to prevent backflow of blood into the ventricles during diastole. Therefore, they remain closed to ensure that the blood does not flow back from the aorta or pulmonary artery into the heart.

This closure of the outflow valves is critical for maintaining effective blood circulation, as it allows the heart to fill completely with blood before the next contraction, ensuring optimal cardiac output and efficiency during the systolic phase.