Question

What is SA node and AV node? Where are they located? What are their functions?

Answer 1

SA Node:

The SA node (SA stands for sinoatrial) is one of the major elements in the cardiac conduction system, the system that controls the heart rate.

Location:

The SA node consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart). Location is precisely the upper right auricular wall.

Function

It initiates electric impulses, thus initiating heart beat. The electrical impulses are generated in SA node. The SA node is also called the sinus node.

The electrical signal generated by the SA node moves from cell to cell down through the heart until it reaches the atrioventricular node (AV node),

AV node :
AV node is atrioventricular node. It is a cluster of cells situated in the center of the heart between the atria and ventricles.
Location:
Precise location is centre of atrio ventricular septum.
Function:
It causes ventricular contractions.
AV node collects signals from SA node.The AV node serves as a gate that slows the electrical current before the signal is permitted to pass down through to the ventricles. This delay ensures that the atria have a chance to fully contract before the ventricles are stimulated. After passing the AV node, the electrical current travels to the ventricles along special fibers embedded in the walls of the lower part of the heart.