Systole occurs just after which heart sound?

Systole occurs just after the first heart sound (S1), which is produced by the closure of the atrioventricular valves (the mitral and tricuspid valves). This sound indicates the start of ventricular contraction, where the ventricles contract to pump blood into the pulmonary artery and aorta. During this contraction phase, known as systole, the heart muscles are actively working to facilitate blood circulation throughout the body.

The first heart sound marks the onset of this critical phase in the cardiac cycle, thus solidifying the connection between S1 and the beginning of systole. Understanding this relationship is key in physiology, especially when monitoring a neonate's heart function, as it provides insights into the timing of the heart's activity.