Sinoatrial Node

Sinoatrial Node

The Sinoatrial Node (SA node) is a group of cells located in the right atrium of the heart. These cells are responsible for initiating the electrical impulses that dictate the heart rate, making the SA node the natural pacemaker of the heart.

Anatomy

The SA node is located in the superior part of the right atrium, near the opening of the Superior vena cava. It is a crescent-shaped structure that is approximately 15 mm in length and 5 mm in width.

Function

The primary function of the SA node is to generate electrical impulses that initiate the heartbeat. These impulses are generated at a rate that is influenced by the autonomic nervous system, with the sympathetic nervous system increasing the rate and the parasympathetic nervous system decreasing it.

Clinical significance

Dysfunction of the SA node can lead to a number of arrhythmias, including sick sinus syndrome and sinus bradycardia. Treatment for these conditions often involves the implantation of an artificial pacemaker.

See also

• Atrioventricular node
• Cardiac action potential
• Cardiac pacemaker

Sinoatrial Node Resources
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