Why SA node is called pace maker of the heart?

Options

A. It can change contractile activity generated by AV node
B. It delays the transmission of impulse between the atria and ventricles
C. It gets stimulated when it receives neural signal
D. It initiates and maintains the rhythmic contractile activity of heart

Answer

**Step-by-Step Solution:**

1. **Understanding the SA Node**: The SA node, or sinoatrial node, is a specialized group of cells located in the right atrium of the heart. It is crucial for the heart's electrical activity.

2. **Role of the SA Node**: The primary function of the SA node is to generate electrical impulses that trigger heartbeats. It acts as the natural pacemaker of the heart.

3. **Impulse Generation**: The SA node generates impulses at a rate of about 70 to 72 beats per minute under normal physiological conditions. This rate can vary based on the body's needs (e.g., during exercise or rest).

4. **Rhythmic Contraction**: The impulses generated by the SA node lead to the contraction of the cardiac muscles, resulting in a rhythmic heartbeat. This rhythmic contraction is essential for effective blood circulation.

5. **Conclusion**: The SA node is called the pacemaker of the heart because it initiates and maintains the rhythmic contractions of the heart muscle, ensuring a consistent heartbeat.

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