AV node cell to bundle of His cell signaling

Definition

Target type: biologicalprocess

Any process that mediates the transfer of information from an AV node cardiac muscle cell to a bundle of His cardiomyocyte. [GOC:BHF, GOC:mtg_cardiac_conduct_nov11]

The atrioventricular (AV) node, situated between the atria and ventricles of the heart, plays a crucial role in regulating the heart's rhythm. Its primary function is to delay the electrical impulse originating from the sinoatrial (SA) node, allowing the atria to contract completely before the ventricles. This delay is achieved through the unique properties of AV node cells.

AV node cells, unlike other cardiac cells, possess a slower rate of depolarization and a longer action potential duration. These characteristics are attributed to their specialized ion channels, which permit a slower influx of sodium and calcium ions and a prolonged efflux of potassium ions. This slower conduction velocity is crucial for ensuring coordinated contraction of the atria and ventricles.

The signal transmission from AV node cells to bundle of His cells, the first component of the ventricular conduction system, is facilitated by the AV node's unique structure and cellular properties. The AV node is composed of specialized cells arranged in a compact structure, resembling a small bundle of fibers. These cells are interconnected by gap junctions, which allow for the rapid flow of ions and electrical signals between adjacent cells.

As the electrical impulse from the SA node reaches the AV node, it triggers a series of events. The impulse first travels through the AV node's upper part, termed the "junctional region", and then enters the "central region", characterized by a slow conduction velocity. This slow conduction is essential for allowing atrial contraction to complete before the ventricles contract. Subsequently, the impulse travels through the "inferior region" of the AV node, where it reaches the bundle of His.

The bundle of His, a group of specialized fibers located at the base of the AV node, acts as a conduit for the electrical signal to the ventricles. The signal then diverges into the right and left bundle branches, which further divide into smaller branches known as Purkinje fibers. These fibers spread throughout the ventricular myocardium, initiating ventricular contraction.

The signaling process from the AV node to the bundle of His involves a complex interplay of ion channels, membrane potentials, and cellular interactions. This intricate mechanism ensures that the electrical impulse is efficiently and accurately transmitted from the atria to the ventricles, maintaining proper heart rhythm and enabling coordinated cardiac function.
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