Question: 162. 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 :
(1) E-C-A-D-B
(2) A-E-C-B-D
(3) B-D-E-C-A
(4) E-A-D-B-C
Answer: Option (1)
Explanation:
The conduction of an action potential in the heart begins at the sinoatrial node,
which acts as the natural pacemaker.
The impulse first originates in the SA node and then spreads to the atria.
From the atria, the impulse reaches the atrioventricular node,
which delays the impulse briefly to allow complete ventricular filling.
The impulse then passes through the atrioventricular bundle, also called the bundle of His.
From the AV bundle, the impulse travels through the right and left bundle branches.
Finally, the impulse is conducted through the Purkinje fibres, causing coordinated contraction of the ventricles.
Thus, the correct sequence is SA node → AV node → AV bundle → Bundle branches → Purkinje fibres, corresponding to E-C-A-D-B.