Which structure is the first in the normal conduction sequence through the His-Purkinje system?

Which structure is the first in the normal conduction sequence through the His-Purkinje system?

• A. SAN
• B. AVN
• C. His bundle
• D. Purkinje fibers

Answer: (A)

The key idea is the sequence of activation inside the His-Purkinje system after the AV node. The impulse travels from the AV node into the His bundle, which is the first part of the His-Purkinje network. From there it moves into the bundle branches and then the Purkinje fibers to rapidly depolarize the ventricles. The sinoatrial node, while the heart’s natural pacemaker, sits upstream of this pathway and is not part of the His-Purkinje sequence. So the first structure encountered in the His-Purkinje system is the His bundle, which links the AV node to the ventricular conduction pathways.

The key idea is the sequence of activation inside the His-Purkinje system after the AV node. The impulse travels from the AV node into the His bundle, which is the first part of the His-Purkinje network. From there it moves into the bundle branches and then the Purkinje fibers to rapidly depolarize the ventricles. The sinoatrial node, while the heart’s natural pacemaker, sits upstream of this pathway and is not part of the His-Purkinje sequence. So the first structure encountered in the His-Purkinje system is the His bundle, which links the AV node to the ventricular conduction pathways.