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MBBS QUESTION #10246
Question 1
Physiological splitting of the second heart sound (S2), which widens further during inspiration, results from delayed closure of which valve relative to the other semilunar valve?
  • The pulmonary valve, due to increased venous return to the right heart during inspiration prolonging right ventricular ejection✔️
  • The aortic valve, due to decreased left ventricular filling during inspiration
  • The mitral valve
  • The tricuspid valve, closing earlier than normal during inspiration
Correct Answer Explanation
Inspiration increases venous return to the right heart (and briefly pools blood in the pulmonary circuit, delaying its return to the left heart), prolonging right ventricular ejection and thus delaying pulmonary valve closure relative to the aortic valve — producing physiological splitting of S2 that widens on inspiration and narrows on expiration.