Question

Name the two valves that open during this phase.

Answer 1

The opening of the vena cava and pulmonary vein close, and the blood enters the ventricles by crossing through the tricuspid and bicuspid valves.

The semilunar valves at the roots of the pulmonary artery and aorta are closed producing the sound "DUBB" to prevent the backflow of blood into ventricles.