what delays electrical impulses
The AV node receives the impulse from the internodal pathways, delays it by approximately 0.09 seconds and the impulse passes through the AV bundle which delays it for a further 0.04 seconds. The AV node and bundle is able to achieve this delay by slowing the conduction of the electrical impulse. The gap junctions between successive cells of the AV node and bundle fibers are fewer which therefore increases the resistance to the impulse.