Which phase begins when pressure in the ventricles exceeds that in the aorta?

The phase that begins when the pressure in the ventricles exceeds that in the aorta is known as late systole, which is characterized by the ejection phase of the cardiac cycle. During late systole, the ventricles contract, generating pressure that surpasses the pressure in the aorta. This pressure gradient causes the aortic valve to open, allowing blood to flow from the ventricles into the aorta.

Understanding the phases of the cardiac cycle is crucial for comprehending heart function and hemodynamics. In late systole, the heart is at its maximal contraction, and the blood is being ejected into systemic circulation.

Other options focus on different stages of the cardiac cycle:

• Isovolumetric contraction refers to the phase immediately following the closing of the AV valves when the ventricles contract but do not yet eject blood, hence pressure has not yet exceeded that in the aorta.

• Early diastole begins after systole ends when the heart muscle relaxes and the ventricles fill with blood, but this does not involve pressure in the ventricles exceeding that in the aorta.

• Isometric relaxation follows the ejection phase and occurs when the ventricles are relaxing, but prior to the opening of the AV valves, and