The cardiac impulse is initiated and conducted further upto ventricle. The correct sequence of conduction of impulse is

Options

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

Answer

To determine the correct sequence of conduction of the cardiac impulse from initiation to the ventricles, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Sinoatrial Node (SA Node)**: The cardiac impulse begins at the SA node, which is located in the right atrium. It is known as the pacemaker of the heart because it generates electrical impulses that initiate each heartbeat.

2. **Atrioventricular Node (AV Node)**: After the SA node generates an impulse, it spreads through the atria, causing them to contract and push blood into the ventricles. The impulse then reaches the AV node, which is located at the junction between the atria and ventricles. The AV node acts as a gatekeeper, briefly delaying the impulse to ensure that the ventricles fill with blood before they contract.

3. **Bundle of His**: The impulse then travels from the AV node to the Bundle of His (also known as the atrioventricular bundle). This bundle is a pathway that conducts the impulse into the ventricles.

4. **Bundle Branches**: The Bundle of His splits into two bundle branches (right and left), which extend into the respective ventricles. These branches carry the impulse further down towards the apex of the heart.

5. **Purkinje Fibers**: Finally, the impulse reaches the Purkinje fibers, which spread throughout the ventricles. This causes the ventricles to contract and pump blood out of the heart to the lungs and the rest of the body.

### Correct Sequence:
The correct sequence of conduction of the cardiac impulse is:
**SA Node → AV Node → Bundle of His → Purkinje Fibers**

### Answer:
The correct answer is **Option A: SA Node, AV Node, Bundle of His, Purkinje Fibers**.

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