___________ is the sound of the tricuspid and mitral valves closing at the end of ventricular filling.

Tricuspid Valves

One of the four heart valves, located between the right atrium and right ventricle, which prevents backflow of blood.

Mitral Valves

Heart valves located between the left atrium and left ventricle that allow blood to flow in one direction: from the atrium into the ventricle.

Ventricular Filling

The phase of the cardiac cycle during which the ventricles of the heart fill with blood from the atria.