Following are the stages of pathway for conduction of an action potential through the heart

A. AV bundle

B. Purkinje fibres

C. AV node

D. Bundle branches

E. SA node

Choose the correct sequence of pathway from the options given below

The correct sequence of the pathway for the conduction of an action potential through the heart is E-C-A-D-B.

Let us break down the electrical conduction system of the heart step-by-step to understand the correct sequence:
1. SA node (Sinoatrial node) [E]: Often called the natural pacemaker of the heart, it is located in the right atrium and initiates the action potential.
2. AV node (Atrioventricular node) [C]: The action potential spreads through the atrial muscle fibers to reach the AV node, where the impulse is briefly delayed to allow the ventricles to fill with blood.
3. AV bundle (Atrioventricular bundle / Bundle of His) [A]: From the AV node, the electrical signal travels along the AV bundle, which is the only electrical connection between the atria and the ventricles.
4. Bundle branches [D]: The AV bundle divides into the right and left bundle branches, which run along the interventricular septum toward the apex of the heart.
5. Purkinje fibres [B]: Finally, the bundle branches distribute the action potential to the Purkinje fibres, which rapidly conduct the impulse throughout the ventricular myocardium, causing ventricular contraction.

Therefore, matching the stages with the correct flow gives:
SA node (E) → AV node (C) → AV bundle (A) → Bundle branches (D) → Purkinje fibres (B).
This corresponds to the sequence E-C-A-D-B.