When does systolic pressure occur?

Systolic pressure refers to the pressure in the arteries when the heart's ventricles contract and pump blood out of the heart. This contraction occurs during the cardiac cycle's systole phase, leading to the ejection of blood into the aorta. Therefore, the correct answer directly relates to the timing of when this pressure is measured.

When considering why the correct choice is associated with a specific event, it's crucial to recognize that the closure of the mitral valve occurs at the end of ventricular systole, which does coincide with the rise in pressure that defines systolic pressure. During this moment, as the left ventricle contracts, blood is pushed into the aorta, resulting in the highest pressure in the arterial system during the cardiac cycle.

The other choices describe moments that either do not pertain to systolic pressure or occur at different phases of the cardiac cycle. During periods of rest, no contraction of the heart occurs (associated with diastolic pressure), and when the ventricles are relaxed, the heart is not exerting pressure, which is characteristic of diastole. The flow of blood into the aorta does occur during systole but is not specific to the measurement of systolic pressure itself, which is defined by the peak pressure