Question

Typical 'lub-dub' sound heard in heart beat are due to

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

Answer 1

The correct option is A

Closure of bicuspid - tricuspid valves followed by semilunar valves

Heart sound

Due to the closure of valves in the heart, heart produces sound.

During the ventricular systole, the pressure inside the ventricles increases which results in closure of the atrio-ventricular valves. Lub sound is produced due to the closure of the atrio-ventricular valves.

The closing of the semilunar valves produce the dub sound following ventricular systole.

Final answer

$\left(D\right)$ Closure of bicuspid - tricuspid valves followed by semilunar valves