Question

Typical 'lubb-dup' sounds heard in heart beat are due to

• A. Closing of bicuspid and tricuspid valves
• B. Closing of semilunar valves
• C. Blood under pressure through aorta
• D. Closure of bicuspid-tricuspid valves followed by semilunar valves

Answer 1

The correct option is D Closure of bicuspid-tricuspid valves followed by semilunar valves

Heart produces two distinct sounds that can be heard with the help of stethoscope. These are 'lubb' and 'dup'.

• Lubb is the first sound which has a low pitch and produced by the closure of tricuspid and bicuspid valves (collectively called atrioventricular valves) at the beginning of ventricular systole.
  
• Dup is the second sound which is sharp and has a high pitch. It is produced by closure of semilunar valves by the end of ventricular systole and beginning of ventricular diastole).

So, the correct answer is 'Closure of bicuspid-tricuspid valves followed by semilunar valves'.