Which phase is characterized by ventricular relaxation after contraction?

Which phase is characterized by ventricular relaxation after contraction?

• A. Isovolumetric Relaxation
• B. Isovolumetric Contraction
• C. Atrial Systole
• D. Ejection

Answer: (A)

Ventricular relaxation after contraction occurs during isovolumetric relaxation. In this phase the ventricles relax but, with both the atrioventricular valves and the semilunar valves closed, there is no change in ventricular volume. Pressure falls quickly until it drops below the atrial pressure, at which point the AV valves open and rapid filling begins. This phase sits between the end of ejection and the start of rapid ventricular filling, distinguishing it from isovolumetric contraction (ventricles contracting with all valves closed), atrial systole (atrial contraction topping off ventricular volume), and ejection (blood leaving the ventricles when the semilunar valves are open).

Ventricular relaxation after contraction occurs during isovolumetric relaxation. In this phase the ventricles relax but, with both the atrioventricular valves and the semilunar valves closed, there is no change in ventricular volume. Pressure falls quickly until it drops below the atrial pressure, at which point the AV valves open and rapid filling begins. This phase sits between the end of ejection and the start of rapid ventricular filling, distinguishing it from isovolumetric contraction (ventricles contracting with all valves closed), atrial systole (atrial contraction topping off ventricular volume), and ejection (blood leaving the ventricles when the semilunar valves are open).