Certified Cardiac Rehabilitation Professional (CCRP) Practice Test

During diastole, the mitral and tricuspid valves are open, allowing blood to flow from the atria into the ventricles. This phase of the cardiac cycle is characterized by the relaxation of the heart muscle following contraction, which allows the heart chambers to fill with blood.

As the ventricles relax, the pressure within them decreases, creating a gradient that encourages blood from the atria (which are also filling with blood returning from the body and lungs) to flow into the ventricles. This crucial phase precedes ventricular contraction and ensures that the heart has adequate blood volume before it pumps blood out into circulation.

This is in contrast to the systole phase, when the heart is contracting and actively pumping blood, causing the mitral and tricuspid valves to close to prevent backflow. The specific terms contraction and relaxation can also refer to distinct aspects of the cardiac cycle, yet they do not capture the encompassing nature of diastole as the period when these valves are assuredly open.