What is SA and AV Node?
The SA (sinoatrial) and AV (atrioventricular) nodes are specialized groups of cells in your heart that control its rhythm. They're crucial for the heart's electrical conduction system, ensuring coordinated contractions.
The SA node, located in the right atrium near the superior vena cava, is the heart's natural pacemaker. [^1, ^4] It generates electrical impulses that trigger the atria to contract, initiating the heartbeat. These impulses spread across the atria, causing them to pump blood into the ventricles. [^1] The SA node is a crescent-shaped cluster of specialized muscle cells. [^3]
AV Node: The Gatekeeper
The AV node, situated between the atria and ventricles, receives the electrical signal from the SA node. [^2, ^7] It acts as a gatekeeper, slightly delaying the signal before transmitting it to the ventricles. [^9] This delay is essential to allow the atria to fully empty their blood into the ventricles before ventricular contraction. [^9] The AV node's function can be suppressed by certain medications like calcium channel blockers. [^7]
How They Work Together
The SA node initiates the heartbeat, and the AV node ensures the proper timing and coordination between atrial and ventricular contractions. The signal travels from the AV node through the bundle of His, bundle branches, and Purkinje fibers to stimulate the ventricles to contract and pump blood to the body. [^6] The interplay between these nodes maintains the rhythmic and efficient pumping action of the heart.
[^1]: The SA (sinoatrial) node generates an electrical signal that causes the upper heart chambers (atria) to contract. The signal then passes through the AV (atrioventricular) node to the lower heart chambers (ventricles), causing them to contract, or pump. The SA node is considered the pacemaker of the heart.
[^2]: The electrical impulse travels from the sinus node to the atrioventricular node (also called AV node). There, impulses are slowed down for a very short period, ...
[^3]: The SA node, or the sinus node, represents a crescent-like cluster of myocytes divided by connective tissue, spreading over a few square millimeters. It is ...
[^4]: The SA node is in the upper part of your heart's right atrium. It is at the edge of your atrium near your superior vena cava (vein that brings oxygen-poor blood ...
[^6]: The main parts of the system are the SA node, AV node, bundle of HIS, bundle branches, and Purkinje fibers. Let's follow a signal through ...
[^7]: Diltiazem, verapamil and nifedipine suppress sinoatrial (SA) nodal function in the excised rabbit heart ... AV node and are useful for treating and preventing AV ...
[^9]: The AV node acts to delay the impulses by approximately 120ms, to ensure the atria have enough time to fully eject blood into the ventricles ...
