What is the Difference Between SA node and AV node?

The SA (sinoatrial) node and the AV (atrioventricular) node are both crucial components of the cardiac conduction system, but they have distinct roles and characteristics. The main differences between the SA node and the AV node are:

1. Function: The SA node generates electrical signals that cause the upper heart chambers (atria) to contract, while the AV node carries the electrical impulse to the lower heart chambers (ventricles), causing them to contract or pump.
2. Location: The SA node is located in the right atrium near the opening of the superior vena cava, while the AV node is present in the right atrium at the base of the interatrial septum or near the opening of the coronary sinus.
3. Size: The SA node is larger in size compared to the AV node.
4. Rhythmicity: The SA node has maximum rhythmicity, while the AV node has less rhythmicity.
5. Firing Rate: The firing rate of the SA node ranges from 60-100 beats per minute (bpm), while the AV node fires at a rate of 40-60 bpm.

In summary, the SA node is responsible for generating electrical impulses that initiate the contraction of the atria, while the AV node relays these impulses to the ventricles, allowing the heart to pump blood effectively. Both nodes play essential roles in maintaining the proper functioning of the heart, and any disturbance in their function can lead to irregular heartbeats (arrhythmia).

Comparative Table: SA node vs AV node

The Sinoatrial (SA) node and Atrioventricular (AV) node are crucial components of the cardiac conduction system, responsible for generating and regulating electrical impulses in the heart. Here is a table highlighting the differences between the SA node and AV node:

The SA node generates electrical signals that cause the upper heart chambers (atria) to contract, while the AV node receives the action potential from the SA node and passes it to the lower heart chambers (ventricles), causing them to contract and pump blood.