Phases of the Cardiac Cycle

Ventricular Filling

The cardiac cycle is a series of events that occur from one heartbeat to the next, ensuring continuous circulation of blood. One crucial phase is ventricular filling, during which blood passively flows into the relaxed ventricles.

Overview of Ventricular Filling

Passive Inflow: Blood enters the ventricles from the atria without active contraction.
Diastole Phase: Occurs when the ventricles are relaxed and pressure inside is low.
Influence of Venous Return: The volume of blood returning to the heart affects the extent of filling.

Phases Within Ventricular Filling

Ventricular filling consists of three sub-phases:

Rapid Filling: Initially, blood flows quickly into the ventricles due to a pressure gradient.
Diastasis: The middle phase characterized by slower filling as pressure equalizes.
Atrial Contraction: The final phase where atrial contraction actively pushes the remaining blood into the ventricles.

Physiological Importance

Proper ventricular filling ensures adequate cardiac output, influencing blood supply to tissues and organs. Any disruption in this process may lead to cardiovascular complications, such as heart failure or atrial fibrillation.