The S2 heart sound corresponds to the closure of which valves?

The S2 heart sound, commonly referred to as the "dub," is produced by the closure of the semilunar valves, which include the aortic and pulmonary valves. This sound occurs at the end of ventricular systole when the ventricles have finished contracting and are beginning to relax. The semilunar valves close to prevent the backflow of blood from the aorta and pulmonary artery into the ventricles, marking the transition from systole to diastole.

In understanding heart sounds, S1 corresponds to the closure of the atrioventricular valves (the mitral and tricuspid valves), while S2 specifically relates to the semilunar valves. This distinction is crucial for assessing cardiac function and recognizing different phases of the cardiac cycle, which is fundamental knowledge in echocardiography and cardiology. Thus, the correct identification of the valves involved in producing the S2 heart sound is key for interpreting heart sounds accurately in clinical practice.