What is the lub-duh sound we hear when listening to the heart?

Question

What is the lub-duh sound we hear when listening to the heart?

Answer 1

The heart pumps out blood as well as have blood return to it.  Hopefully, it only goes one way on its track through the blood stream.  It's probably the pump in and pump out sound that you are hearing.

Answer 2

Lub is the closing of the atrioventricular (AV) valves closing during ventricular contraction.  Dub is the closing of the semilunar valves closing during ventricular relaxation.  Note that in both cases the sound results from the closing of a valve set.  The valves close to prevent backflow into an area.  AV valves stop backflow from ventricles to atria.  Semilunar valves prevent backflow from arteries (aorta and pulmonary artery) to the ventricles.

Answer 3

The heart valves opening and closing.

Answer 4

The lub dub is in fact that valves opening and closing. the 'lub' is the valves closing after blood is taken in to the camber's, and the dub is the other valves (on the other side of the heart) closing after the blood is being pushed into the aorta. That is the simplest way i can explain it!

hope it helps,

m