Maximum filling of the ventricles takes place during which phase of the cardiac cycle?

Options

A. Protodiastoie
B. Isovolumetric ventricular relaxation phase
C. Ventricular diastole proper
D. Last rapid filling phase due to atrial systole

Answer

To determine during which phase of the cardiac cycle maximum filling of the ventricles occurs, let's analyze the phases of the cardiac cycle step by step.

### Step-by-Step Solution:

1. **Understand the Cardiac Cycle Phases**: The cardiac cycle consists of several phases, primarily including:
- Isovolumetric Ventricular Contraction
- Rapid Ejection
- Reduced Ejection
- Isovolumetric Relaxation
- Atrial Contraction

2. **Identify the Filling Phases**: The filling of the ventricles primarily occurs during:
- **Ventricular Diastole**: This is when the ventricles are relaxed and filling with blood.
- **Atrial Contraction**: This phase occurs at the end of diastole when the atria contract to push additional blood into the ventricles.

3. **Focus on Atrial Contraction**: During atrial contraction, the atria contract and contribute to the final filling of the ventricles. This phase accounts for about 10% of the total ventricular filling volume.

4. **Conclusion**: The maximum filling of the ventricles occurs during the **Atrial Contraction** phase, which is the last phase of ventricular diastole.

### Final Answer:
Maximum filling of the ventricles takes place during the **Atrial Contraction** phase of the cardiac cycle.

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