During the heart beating 'Lubb' and 'Dup' sounds are produced, but the Dup sound as to be heard first
as the deoxygenated blood enters first to the right auricle and then only the it enters to the pulmonary artery and then into aorta. why only lubb sound come first why not the dup sound

Asked by P VISHNU | 4th Aug, 2015, 08:30: PM

Expert Answer:

Lubb sound which is produced at the time of ventricular systole is the loudest and for longer duration than the dup sound produced during the atrial systole.

The lubb is called the first sound of the heart and the dub is called the second sound of the heart because the normal pumping cycle of the heart is considered to begin at the onset of ventricular systole which includes the closure of atrio-ventricular valves.

Answered by Hemangi Binny | 5th Aug, 2015, 09:15: AM