Which heart sound is produced by the closure of the aortic and pulmonic valves?

Which heart sound is produced by the closure of the aortic and pulmonic valves?

• A. S1
• B. S2
• C. S3
• D. S4

Answer: (B)

The second heart sound is produced by the closure of the semilunar valves (the aortic and pulmonic valves) at the end of systole. When these valves snap shut, the sudden stop in blood flow and the slight rebound of blood against the closed leaflets create a short, sharp sound that marks the beginning of diastole. This sound is often described as having two components corresponding to the aortic and pulmonic valves, which can be heard as a single sound most of the time but may split with inspiration as the pulmonic valve closes slightly later. By contrast, the first heart sound comes from the closure of the atrioventricular valves at the start of systole, and S3 and S4 are extra heart sounds related to rapid ventricular filling and a stiff ventricle, respectively.

The second heart sound is produced by the closure of the semilunar valves (the aortic and pulmonic valves) at the end of systole. When these valves snap shut, the sudden stop in blood flow and the slight rebound of blood against the closed leaflets create a short, sharp sound that marks the beginning of diastole. This sound is often described as having two components corresponding to the aortic and pulmonic valves, which can be heard as a single sound most of the time but may split with inspiration as the pulmonic valve closes slightly later. By contrast, the first heart sound comes from the closure of the atrioventricular valves at the start of systole, and S3 and S4 are extra heart sounds related to rapid ventricular filling and a stiff ventricle, respectively.