Heart sounds?

Question

Using a stethoscope on your chest you should hear a low-pitched "lub" sound followed by a higher-pitched, more forceful "dup". "Lub" is the sound of the atrioventricular valves closing. Would this mark the beginning of systole or diastole?

"Dup" is heard when the semilunar valves close. Is "dup" the beginning of systole or diastole?

Answer 1

The first sound marks the beginning of diastole.

-atrioventricular valves opened

-semilunar valves closed

The second marks systole

-atrioventricular valves closed

-semilunar valves opened

Answer 2

http://www.med.ucla.edu/wilkes/Physiolog...

Answer 3

The lub marks systole (the atrioventricular valves close and the ventricles contract).  The dub marks diastole (the semilunar valves close, the ventricles fill, and the atria contract).