SA Node and AV Node

The heart muscle pumps blood in our body without a break. A human heart is similar to a machine that continuously works to keep all the organs in the body working. The heart contracts and relaxes, triggering a whole process of circulation. Each contraction occurs at a set time and is triggered by an electrical impulse. These electrical impulses are controlled by a group of cells called the nodes. These nodes are the SA node and AV node. When these nodes weaken, it leads to many heart diseases that affect the blood circulation. Let us have a look at SA node and AV node and understand the difference between them.

Information on SA Node and AV Node

As mentioned above the SA node and AV node is a group of specialized cells. The SA node function differs from the AV node function. The following paragraphs will discuss these nodes in detail and help you understand the difference between SA node and AV node.

SA Node
The SA node is short for sinoatrial node. It is the impulse generating tissue, in simple words, a pacemaker. The SA node location is in the right atrium of the heart. These group of cells are placed on the wall of the right atrium, near the entry point of superior vena cava. The SA node triggers the electrical impulses that are carried around to other heart cells. The electrical impulses cause the atria to contract at a rate of 60 to 100 beats per minute. SA node dysfunction will cause irregular heart beats. SA node dysfunction causes the heart rhythms to become too fast, too slow or occur in combination.

AV Node
The AV node is short for atrioventricular node. The AV node is a group of cells that are a part of electrical control system of the heart. They help in coordinating the heart rate. The AV node location is between the atria and the ventricles of the heart. They are present in the interatrial septum of the heart near the opening of coronary sinus. The AV node location is at the center of Koch's Triangle. This triangle consists of the tricuspid valve, coronary sinus and the interatrial septum.

The AV node function begins when it gets an electrical impulse from the SA node. The SA node initiates the electrical impulse that reaches the AV node first. The rhythm of the heart contractions is set by the AV node. It delays the impulse by about 0.12 seconds. This is delay is very important as it helps the atria eject the blood in them into the ventricles before the contraction of the ventricles. The delay also helps in protecting the ventricles from atrial arrhythmia (type of arrhythmia). The AV nodes contraction rate is about 40 to 60 time/minute. AV node dysfunction includes many heart disorders like atrioventricular conduction disease, atrioventricular nodal re-entry tachycardia, etc. You can read in detail about the first degree AV block.

Difference Between SA Node and AV Node

You must have by now understood the basic difference between SA node and AV node. Some of the difference between SA node and AV node are enlisted in the following table for better understanding.

Difference Between SA Node and AV Node
Difference	SA Node	AV Node
Location	SA node location is in the right atrium. It is present near the opening of superior vena cava.	AV node location is in between the atria and the heart ventricles. It is present near the opening of the opening of the coronary sinus.
Stimulation	SA node is stimulated by the cardiac centers of the medulla oblongata.	The AV node is stimulated by the stimulated by cardiac impulses initiated by SA node.
Function	The SA node function is to initiate and maintains cardiac rhythm. It is therefore called the pacemaker of the heart.	The AV node function is to the AV node set the rhythm of your heart contractions.

This was all about the SA node and AV node. Atrial fibrillation causes the problems with the heart's electrical system. This means, the electrical impulses are not just generated in the SA node, but in different areas as well. This causes a high pulse rate and the right atrium fails to pump blood into the ventricle at the right time. This causes blood depreciation in the body. Therefore, surgery is the option and the person is fitted with an artificial pacemaker to help stabilize the electrical impulses. Hope you have found some useful information on SA node and AV node from the above paragraphs.