‘Lub-dup’ sound is produced due to action of

‘Lub-dup’ sound is produced due to action of

Large intestine
Lungs
Heart
Oesophagus
This question was previously asked in
UPSC NDA-1 – 2015
The ‘lub-dup’ sounds are characteristic heart sounds. The ‘lub’ sound occurs during systole when the atrioventricular valves (mitral and tricuspid) close. The ‘dup’ sound occurs during diastole when the semilunar valves (aortic and pulmonary) close. These sounds are produced by the vibrations of the valves, heart walls, and blood flow.
The ‘lub-dup’ sounds are associated with the closure of heart valves during the cardiac cycle.
These sounds can be heard using a stethoscope. Abnormal heart sounds, called murmurs, can indicate underlying issues with valve function or blood flow.