Opening and closing of the heart valves is caused by ________.

A) breathing
B) gravity
C) valves contracting and relaxing
D) osmotic gradients
E) pressure gradients

Heart Valves

Structures within the heart that maintain unidirectional blood flow through the heart chambers, including the mitral, tricuspid, aortic, and pulmonary valves.

Pressure Gradients

A differentiation in pressure that drives the movement of fluids or gases from areas of high pressure to areas of low pressure.

Osmotic Gradients

The difference in concentration of solutes across a semipermeable membrane, which drives the movement of water.