Origin of heart beat and its conduction is represented by

Options

A. AV budle `to` Bundle of His `to` SA node `to` Purkinje fibres
B. SA node `to` Purkinje fibres `to` AV node `to` Bundle of His
C. Purkinje fibres `to` AV node `to` Bundle of His `to` SA node
D. SA node `to` AV node `to` Bundle of His `to` Purkinje fibres

Answer

To solve the question regarding the origin of the heartbeat and its conduction pathway, we will analyze the options provided and identify the correct sequence of events.

### Step-by-Step Solution:

1. **Identify the Origin of Heartbeat**: The heartbeat originates from the Sinoatrial (SA) node, which is known as the pacemaker of the heart. This is the first step in the conduction pathway.

2. **Conduction to Atrioventricular (AV) Node**: After the SA node generates an electrical impulse, this impulse spreads through the atrial muscles, causing them to contract. The impulse then reaches the Atrioventricular (AV) node.

3. **From AV Node to Bundle of His**: The electrical signal is then transmitted from the AV node to the Bundle of His (also known as the atrioventricular bundle). This structure conducts the impulses from the atria to the ventricles.

4. **Conduction to Purkinje Fibers**: Finally, the impulse travels from the Bundle of His to the Purkinje fibers, which spread throughout the ventricles, leading to their contraction.

5. **Summarizing the Sequence**: The correct sequence of conduction is:
- SA node → AV node → Bundle of His → Purkinje fibers.

6. **Choosing the Correct Option**: Among the given options, the one that matches this sequence is option D: SA node to AV node to Bundle of His and then to Purkinje fibers.

### Final Answer:
The correct representation of the origin of heartbeat and its conduction is:
**SA node → AV node → Bundle of His → Purkinje fibers (Option D)**.

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