Which valves are associated with the closure sound known as S1?

The closure sound known as S1 is primarily associated with the closure of the mitral and tricuspid valves. This sound occurs at the beginning of ventricular contraction, marking the onset of systole. When the ventricles contract, these valves close to prevent backflow of blood into the atria, leading to the pronounced sound characteristic of S1.

The timing of S1 coincides with the electrical conduction of the heart, specifically the depolarization of the ventricles. This closure also effectively signifies the end of the diastolic filling phase and the transition into the pumping phase of the heart, thus playing a crucial role in cardiac cycle dynamics.

While the aortic and pulmonary valves are responsible for the closure sound S2, which occurs at the end of systole when the ventricles finish contracting and blood is ejected into the aorta and pulmonary artery, that closure sound is distinct and occurs later in the cardiac cycle. In contrast, the with S1 is specifically tied to the activity of the mitral and tricuspid valves, marking a key auditory marker in heart auscultation.