Understanding the Ventricular Filling Phase During Diastole

Ventricular Filling : Systole or Diastole?

Ventricular filling occurs during diastole. Diastole is the relaxation phase of the cardiac cycle when the heart muscle is relaxed and the ventricles are filling with blood. During this phase, the atria contract (atrial systole) and push blood into the ventricles through the open atrioventricular valves (mitral and tricuspid valves). This phase allows blood to flow passively into the ventricles from the atria.

The ventricular filling phase consists of two main stages. The first stage is called rapid ventricular filling, where blood flows quickly from the atria into the ventricles. This rapid filling occurs due to the pressure gradient between the higher pressure in the atria and the lower pressure in the relaxed ventricles.

The second stage is called diastasis, where the ventricles continue to fill at a slower pace. During this stage, the atria are relaxed, and the ventricles are still expanding, gradually increasing their volume.

Finally, towards the end of diastole, the atria contract once again (atrial systole), forcing the remaining blood into the ventricles. This stage is known as atrial kick and provides the final boost to ventricular filling before the next contraction (systole) begins.

In summary, ventricular filling primarily occurs during diastole, allowing for the passive flow of blood from the atria into the ventricles.

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