Multiple choice

The first heard heart sound is:

  1. “Dupp” sound at the end of systole

  2. “Lubb” sound at the beginning of systole

  3. “Lupp” sound at the beginning of systole

  4. “Lubb” sound at the end of systole
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The first heart sound (S1) is the "lubb" sound caused by the closure of the atrioventricular valves (mitral and tricuspid) at the beginning of systole. The second heart sound (S2) is the "dupp" sound caused by semilunar valve closure at the end of systole.

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