Which of the following is correct represntation of flow of action potential through conduction system of heart?

Options

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

Answer

To determine the correct representation of the flow of action potential through the conduction system of the heart, we can analyze the sequence of events that occur during cardiac conduction.

### Step-by-Step Solution:

1. **Identify the Starting Point**: The conduction of action potential in the heart begins at the **Sinoatrial (SA) node**. This is the natural pacemaker of the heart, located in the right atrium.

**Hint**: Remember that the SA node initiates the heartbeat and sets the rhythm.

2. **Flow to the Atria**: From the SA node, the action potential spreads through the walls of the **right atrium** and into the **left atrium**, causing both atria to contract.

**Hint**: The atrial contraction is essential for filling the ventricles with blood.

3. **Reach the Atrioventricular (AV) Node**: After the atria contract, the action potential travels to the **Atrioventricular (AV) node**. This node serves as a gatekeeper, briefly delaying the signal before it moves to the ventricles.

**Hint**: The delay at the AV node allows the ventricles to fill with blood before they contract.

4. **Bundle of His**: From the AV node, the action potential moves into the **Bundle of His** (also known as the atrioventricular bundle), which is located in the interventricular septum.

**Hint**: The Bundle of His is crucial for transmitting the signal from the atria to the ventricles.

5. **Purkinje Fibers**: Finally, the action potential travels through the **Purkinje fibers**, which spread throughout the ventricles, leading to their contraction.

**Hint**: The Purkinje fibers ensure that the ventricles contract in a coordinated manner.

### Conclusion:
The correct sequence of the flow of action potential through the conduction system of the heart is:
- **SA Node → AV Node → Bundle of His → Purkinje Fibers**.

Thus, the correct answer is **Option 4**.