Question

Select the correct answer from each drop-down menu.

Which event creates the first 'lub' sound and the second heart sound or 'dub' sound?

Answer 1

The “lub” is the first heart sound, commonly termed S1, and is caused by turbulence caused by the closure of mitral and tricuspid valves at the start of systole. The second sound,” dub” or S2, is caused by the closure of aortic and pulmonic valves, marking the end of systole.