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)

Closure of the aortic and pulmonic valves produces the second heart sound. This occurs at the start of diastole when the ventricles relax and arterial pressure causes the semilunar valves to snap shut, creating a higher-pitched, short “dub.” Sometimes a split is heard on inspiration because the pulmonic valve closes a touch later than the aortic valve. The first heart sound comes from the closure of the mitral and tricuspid valves at the beginning of systole, while S3 and S4 are due to rapid ventricular filling and atrial contraction, not valve closure.

Closure of the aortic and pulmonic valves produces the second heart sound. This occurs at the start of diastole when the ventricles relax and arterial pressure causes the semilunar valves to snap shut, creating a higher-pitched, short “dub.” Sometimes a split is heard on inspiration because the pulmonic valve closes a touch later than the aortic valve. The first heart sound comes from the closure of the mitral and tricuspid valves at the beginning of systole, while S3 and S4 are due to rapid ventricular filling and atrial contraction, not valve closure.