Ventricular systole is stimulated by

Options

A. SA node
B. AV valve
C. AV node
D. AV aperture

Answer

**Step-by-Step Solution:**

1. **Understanding Ventricular Systole**:
- Ventricular systole refers to the phase of the cardiac cycle when the ventricles contract. This contraction is essential for pumping blood out of the heart to the lungs and the rest of the body.

2. **Identifying the Stimulus for Contraction**:
- The contraction of the ventricles is initiated by a wave of electrical activity that spreads through the heart muscle. This wave is crucial for coordinating the heart's contractions.

3. **Role of the Atrioventricular Node (AV Node)**:
- The AV node is a critical component of the heart's conduction system. It receives impulses from the sinoatrial (SA) node and then transmits these impulses to the ventricles, causing them to contract.

4. **Evaluating the Options**:
- Option A: SA node - This node initiates the heartbeat but does not directly stimulate ventricular contraction.
- Option B: AV valve - This is a structure that prevents backflow of blood and does not stimulate contraction.
- Option C: AV node - This is the correct answer as it stimulates the contraction of the ventricles.
- Option D: AV aperture - This term is not commonly used in the context of cardiac physiology.

5. **Conclusion**:
- Based on the understanding that the AV node is responsible for stimulating the contraction of the ventricles during ventricular systole, the correct answer is **Option C: AV node**.

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