Question

Differentiate between the following pairs on the basis of the criteria mentioned within the brackets.

LUB and DUB (names of the valves whose closure produce the sound).

Answer 1

LUB is the first heart sound and is produced when the ventricles contract and the atrioventricular valves close. DUB is the second heart sound and is heard during closure of semilunar valves caused by relaxation of the ventricles.