sinoatrial node

[ sahy-noh-ey-tree-uhl, sahy- ]

noun

, Anatomy.

1. a small mass of tissue in the right atrium functioning as pacemaker of the heart by giving rise to the electric impulses that initiate heart contractions.

sinoatrial node

/ sī′nō-ā′trē-əl /

1. A small mass of specialized cardiac muscle fibers that acts as a pacemaker by initiating and maintaining normal heartbeat and cardiac rhythm. It is located in the right atrium.

Word History and Origins

Origin of sinoatrial node¹

1920–25; sino- + atrial ( def )

Example Sentences

A heartbeat begins when the organ’s pacemaker, a structure called the sinoatrial node, fires off an electrical impulse that disperses across the atria, the blood-collecting chambers.

From Science Magazine

TBX18 is normally active in embryos, where it triggers, among other things, the formation of the heart’s rhythm keeping centre, the sinoatrial node.

From Forbes

In healthy people, a small region of the heart, called the sinoatrial node, fires the electrical impulses that determine heart rate.

From Scientific American

In 12 pigs, the team mimicked a fatal human heart condition in which electrical activity cannot spread through the heart from the sinoatrial node, forcing other, weaker parts of the heart to take over.

From Nature

Instead, she went on about P waves and the sinoatrial node and what my mom’s EKG looked like, all at lightning speed.

From Time