Q.The second heart sound (dubb) is associated with the closure of

The second heart sound, "dub," accompanies the closing of the semilunar valves — the valves guarding the openings of the pulmonary artery and the aorta. The first heart sound, "lub," is the one associated with the closing of the tricuspid and bicuspid valves instead …

Each cardiac cycle produces two clear sounds that can be heard easily with a stethoscope:

• The first heart sound ("lub") accompanies the closing of the tricuspid and bicuspid valves, which happens as ventricular pressure rises during ventricular systole and prevents blood flowing back into the atria. …

Method: Matching an Event in a Cycle to Its Correct Trigger

Use this approach whenever a question asks which structural event (a valve closing, a gate opening) causes a named event in a repeating cycle.

Steps

Step 1: Note which position in the cycle the event occurs at

The first heart sound corresponds to early systole; the second corresponds to early diastole — position in the cycle is the key clue.

Step 2: Recall which valve set closes at each of those two positions

AV valves (tricuspid, bicuspid) close as the ventricles begin to contract; semilunar valves close as the ventricles begin to relax.

Step 3: Match the named sound to the correct valve set based on cycle position, not rote memorisation …