Question

When do the valves open and close

Answer 1

When the ventricles relax, atrial pressure exceeds ventricular pressure, the AV valves are pushed open and blood flows into the ventricles. However, when the ventricles contract, ventricular pressure exceeds atrial pressure causing the AV valves to snap shut.

Answer 2

$Hey MATE!$

The valves in our heart open and close only and only when blood from whole body comes to upper chambers and then goes to lower chambers via bicuspid and tricuspid valve.

Hope it helps

Hakuna Matata :))