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NEET · Biology · STD 11 - 15. Body fluids and criculations

Doctors use stethoscope to hear the sounds produced during each cardiac cycle. The second sound is heard when

  1. A \(AV\) node receives signal from \(SA\) node
  2. B \(AV\) valves open up
  3. C Ventricular walls vibrate due to gushing in of blood from atria
  4. D Semilunar valves close down after the blood flows into vessels from ventricles.
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Answer & Solution

Correct Answer

(D) Semilunar valves close down after the blood flows into vessels from ventricles.

Step-by-step Solution

Detailed explanation

(d) : Second heart sound \(i.e.\), dup is caused by the closure of the semilunar values and marks the end of ventricular systole.