S2 is the heart sound produced by the closing of which valves?

S2 is the heart sound produced by the closing of which valves?

• A. Atrioventricular valves
• B. Semilunar valves
• C. Both valve types sequentially
• D. None of the above

Answer: (B)

S2 comes from the end of ventricular contraction when the semilunar valves—the aortic and pulmonary valves—snap shut as ventricular pressure falls below the arterial pressures. This closure stops the flow back into the ventricles and creates the second heart sound. You can usually hear two components: A2 from the aortic valve and P2 from the pulmonic valve. Sometimes they’re heard separately as a split S2, especially with deep inspiration. By contrast, S1 is produced when the atrioventricular valves close at the start of ventricular systole.

S2 comes from the end of ventricular contraction when the semilunar valves—the aortic and pulmonary valves—snap shut as ventricular pressure falls below the arterial pressures. This closure stops the flow back into the ventricles and creates the second heart sound. You can usually hear two components: A2 from the aortic valve and P2 from the pulmonic valve. Sometimes they’re heard separately as a split S2, especially with deep inspiration. By contrast, S1 is produced when the atrioventricular valves close at the start of ventricular systole.