Heart beat is initiated by

Options

A. A V node
B. SA node
C. Bundle of His
D. Purkinje fibres

Answer

**Step-by-Step Solution:**

1. **Understanding the Heart's Electrical System**: The heart has a specialized electrical conduction system that controls the heartbeat. This system includes several key components: the SA node, AV node, bundle of His, and Purkinje fibers.

2. **Identifying the SA Node**: The SA node, also known as the sinoatrial node, is located in the right atrium of the heart. It is a cluster of cells that plays a crucial role in initiating the heartbeat.

3. **Function of the SA Node**: The SA node generates electrical impulses autonomously. This means it can create signals without external stimulation. These impulses spread through the heart muscle, causing the atria to contract and pump blood into the ventricles.

4. **Natural Pacemaker**: The SA node is often referred to as the "natural pacemaker" of the heart because it sets the rhythm for the heartbeat. It regulates the heart rate by controlling the timing of the electrical impulses.

5. **Conclusion**: Based on this information, the correct answer to the question "Heart beat is initiated by" is the SA node (option B).

**Final Answer**: The heartbeat is initiated by the SA node.

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