origin of heart beat is from -

Options

A. S.A. Node
B. A. V. Node
C. Vagus Nerve
D. Cardiac Nerve

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the origin of the heartbeat. This refers to where the electrical impulses that initiate the heartbeat are generated.

2. **Identifying the Key Structure**: The primary structure responsible for the origin of the heartbeat is the Sinoatrial (SA) node. This is a specialized group of cells located in the right atrium (auricle) of the heart.

3. **Function of the SA Node**: The SA node acts as the heart's natural pacemaker. It generates electrical impulses that trigger heartbeats. These impulses occur approximately every 0.8 seconds, which corresponds to the normal rhythm of the heart.

4. **Myogenic Nature of the Heart**: The heart is described as myogenic, meaning that the heartbeat originates from the heart muscle itself rather than external stimuli. This is a crucial point as it emphasizes that the heart has an intrinsic ability to contract.

5. **Transmission of Impulses**: After the SA node generates an impulse, it spreads to the Atrioventricular (AV) node and then travels through the ventricles, leading to coordinated contractions of the heart muscle.

6. **Conclusion**: Based on the information, the origin of the heartbeat is from the SA node, which is part of the nodal tissue in the heart.

**Final Answer**: The origin of the heartbeat is from the SA node.

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