Question

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

• A. E-C-A-D-B
• B. A-E-C-B-D
• C. B-D-E-C-A
• D. E-A-D-B-C

Answer 1

The Correct Option is A

The propagation of an action potential through the heart comprises distinct phases, involving the successive activation of cardiac electrical system regions to ensure a coordinated heartbeat. The accurate order is as follows:

1. SA node (Sinoatrial node): This node generates the initial electrical signal, functioning as the heart's natural pacemaker, which triggers atrial contraction.
2. AV node (Atrioventricular node): The SA node's impulse is transmitted to the AV node, where a brief delay occurs. This pause permits adequate ventricular filling with blood prior to ventricular contraction.
3. AV bundle (Bundle of His): This structure serves as a conduit, relaying the electrical impulse from the AV node to the ventricles.
4. Bundle branches: These branches conduct the impulse through the interventricular septum, bifurcating the signal to reach both the left and right ventricles.
5. Purkinje fibres: These fibres distribute the electrical impulse throughout the ventricular myocardium, eliciting ventricular contraction.

Consequently, the sequence aligning with the given options is E-C-A-D-B, representing the SA node, AV node, AV bundle, Bundle branches, and Purkinje fibres, in that order.