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

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

• A. Closure of AV valves
• B. S3
• C. Closure of semilunar valves
• D. S4

Answer: (C)

S2 marks the closure of the semilunar valves, the aortic and pulmonary valves, at the end of systole when the ventricle pressure drops below the pressure in the aorta and pulmonary artery, causing these valves to snap shut and produce the characteristic "dub" sound. This contrasts with S1, which comes from the closure of the atrioventricular valves (mitral and tricuspid) at the start of systole. S3 and S4 are extra heart sounds not tied to valve closure: S3 occurs with rapid ventricular filling in early diastole, and S4 with atrial contraction against a stiff ventricle late in diastole.

S2 marks the closure of the semilunar valves, the aortic and pulmonary valves, at the end of systole when the ventricle pressure drops below the pressure in the aorta and pulmonary artery, causing these valves to snap shut and produce the characteristic "dub" sound. This contrasts with S1, which comes from the closure of the atrioventricular valves (mitral and tricuspid) at the start of systole. S3 and S4 are extra heart sounds not tied to valve closure: S3 occurs with rapid ventricular filling in early diastole, and S4 with atrial contraction against a stiff ventricle late in diastole.