Q.What is the significance of atrio-ventricular node and atrio-ventricular bundle in the functioning of heart?

The atrio-ventricular node and atrio-ventricular bundle carry the heart's electrical signal from the atria down to the ventricles so the two sets of chambers contract in the correct order.

• The atrio-ventricular node (AVN) lies in the lower left corner of the right atrium, near the atrio-ventricular septum, and picks up the impulse after the atria are excited.
• From the AVN, the atrio-ventricular bundle (AV bundle) runs through the atrio-ventricular septa and onto the top of the inter-ventricular septum.
• There it divides into a right and a left bundle, which give off fine Purkinje fibres that spread the impulse throughout the ventricular muscle. …

When the sino-atrial node fires and the atria are excited, that electrical signal must somehow be carried onward to the ventricles, because the atria and ventricles are otherwise separated. The atrio-ventricular node and the atrio-ventricular bundle are the structures that make this handover possible.

The atrio-ventricular node, or AVN, is a mass of nodal tissue lying in the lower left corner of the right atrium, close to the atrio-ventricular septum. It is positioned to receive the action potential once it has swept across the atria. From the AVN a bundle of nodal fibres, the atrio-ventricular bundle or AV bundle, carries the impulse forward:

• It passes through the atrio-ventricular septa and emerges on top of the inter-ventricular septum.
• There it promptly divides into a right bundle and a left bundle, one for each ventricle.
• These bundles give off very fine fibres, the Purkinje fibres, which spread throughout the ventricular muscle of their respective sides. …

Method: Explaining the Significance of a Relay Structure in a Conduction Pathway

Use this approach for any question asking about the role/significance of an intermediate structure that passes a signal or substance along a pathway.

Steps

Step 1: State what the structure receives, and from where

The AVN receives the impulse only after it has already swept across the atria — name the source explicitly.

Step 2: Trace the physical route the structure carries the signal through, in anatomical order

AV bundle → through the atrio-ventricular septa → top of the inter-ventricular septum → right and left bundles → Purkinje fibres. Skipping a stage or reversing the order is a common mistake to avoid. …