Most of us are unaware of the electricity coursing through our hearts at every moment of every day. If you take your own pulse right now, you are feeling blood being shot through your arteries by the powerful contractions in your heart, caused by an electrical current. When all is well, we don’t even notice it – but there is electricity inside us all.
When thinking about the electrical system of the heart, what better place to start than where this electrical impulse begins?
About the SA Node
On the upper right side of your heart (right atrium) there is a bundle of cells called the SA node (sinoatrial node). This small collection of neurons creates the pulse of power that keeps you alive. From there, the surge of electricity travels along conducting cells where it makes its first stop – the AV node (atrioventricular node). This second bundle of cells has two important functions. First, it delays the electrical impulse just long enough so that the upper chambers can empty all of the blood, before filling up again. Second, it sends the impulse along to a bundle of other neurons that distribute it into the muscle around the lower chambers of your heart (ventricles).