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NEET2024ZoologyBody Fluids and CirculationActual

'Lub' sound of Heart is caused by the ______

Options

  1. Aclosure of the semilunar valves
  2. Bopening of tricuspid and bicuspid valves
  3. Copening of the semilunar valves
  4. Dclosure of the tricuspid and bicuspid valves

Correct answer

D. closure of the tricuspid and bicuspid valves

Step-by-step solution

The correct answer is option (4) because LUB is the first heart sound and it is produced by closing of AV valves; (tricuspid valve in between right atrium and right ventricle) and (bicuspid /mitral valve in between left atrium and left ventricle), during ventricular systole. - Option (1) is incorrect as closure of the semilunar valves produce the second heart sound called 'DUB'. - Option (2) is incorrect because opening of valves are not responsible for production of heart sounds 'LUB' and 'DUB'. - Option (3) is in

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