How much time does ventricular systole last? Which valves close during this phase?

Explanation

**Step-by-Step Solution:**

1. **Understanding Ventricular Systole**: Ventricular systole is the phase of the cardiac cycle during which the ventricles contract to pump blood out of the heart. This contraction is initiated by electrical impulses generated by the sinoatrial (SA) node and transmitted through the atrioventricular (AV) node and the bundle of His.

2. **Duration of Ventricular Systole**: The duration of ventricular systole is approximately 0.3 seconds. This is a brief but critical period during which the heart effectively pumps blood.

3. **Valves Involved During Ventricular Systole**: During ventricular systole, the atrioventricular (AV) valves, specifically the tricuspid valve (on the right side of the heart) and the mitral valve (on the left side of the heart), close. This closure prevents the backflow of blood into the atria as the ventricles contract.

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