Word parts
sin/o sinusatri/o atrium
What it means
The heart's natural pacemaker. It sends out electrical signals at about 60 to 100 times a minute at rest, which spread across the atria and then to the ventricles through the AV node. A normal rhythm started here is called normal sinus rhythm. The autonomic nervous system speeds it up or slows it down.
At a glance
| Abbreviations | SA (sinoatrial) |
|---|---|
| Spanish | nódulo sinoauricular |
| Also written | sinoatrial node, sinus node, SA nodes |
Related terms
arrhythmia
A heart rhythm that is not normal: too fast, too slow or irregular.
electrocardiogram
A test that records the heart's electrical activity as waves on paper or a screen.
conduction
The passing of something, such as an electrical signal or heat, from one place to another through a material.
atrial
Relating to an atrium, one of the two upper chambers of the heart.
cardiac muscle
The muscle tissue that makes up the walls of the heart.