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

Options

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

Answer

To determine the correct representation of the flow of action potential through the conduction system of the heart, we need to understand the sequence of events that occur during cardiac conduction. Here’s a step-by-step breakdown:

### Step 1: Identify the Starting Point
The conduction system of the heart begins at the **Sinoatrial (SA) Node**. This node is often referred to as the natural pacemaker of the heart, where the action potential is initiated.

### Step 2: Action Potential Travels to the Atrioventricular Node
After the SA node, the action potential travels to the **Atrioventricular (AV) Node**. This node serves as a critical relay point that allows the atria to contract before the ventricles.

### Step 3: From AV Node to Bundle of His
Next, the action potential moves from the AV node to the **Bundle of His** (also known as the Atrioventricular Bundle). This bundle conducts the impulses from the AV node down into the ventricles.

### Step 4: Bundle of His to Purkinje Fibers
Finally, the action potential travels from the Bundle of His to the **Purkinje Fibers**. These fibers spread throughout the ventricles, causing them to contract and pump blood out of the heart.

### Conclusion
The correct sequence of the flow of action potential through the conduction system of the heart is:
1. SA Node
2. AV Node
3. Bundle of His
4. Purkinje Fibers

Thus, the correct representation of the flow of action potential is **SA Node → AV Node → Bundle of His → Purkinje Fibers**.

### Answer
The correct option is **D: SA Node to AV Node, then to Bundle of His, and finally to Purkinje Fibers**.

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