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# Sinoatrial Node The sinoatrial (SA) node is a cluster of cells that act as a natural pacemaker. The SA node is located in a wall of the right atrium. ## Function - It triggers the electrical impulses that are carried around to other heart cells - The electrical impulses cause the atria to cont...

# Sinoatrial Node The sinoatrial (SA) node is a cluster of cells that act as a natural pacemaker. The SA node is located in a wall of the right atrium. ## Function - It 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 - Signals atria to contract, passes the blood to bottom - Causes contraction # The atrioventricular (AV) node ## AV node - Atrioventricular node - Electrically connects atrial and ventricular chambers - Specialized tissue between the atria and the ventricles of the heart - Also automatically generates impulses - cause contraction This node is very similar to the SA node but smaller, and electricity travels slower here. The slowing effect gives the ventricles enough time to expand and fill up with blood.