Eli5: How does the heart keep beating, and how did it start beating in the first place?

Question

Eli5: How does the heart keep beating, and how did it start beating in the first place?

In: 1

Answer 1

The heart has two regions which act as natural pace makers: the predominant one is the SA Node (sino-atrial) and the secondary one is the AV Node, atrial ventricular.

These regions kick off the contraction process for the entire heart. The SA Node fires a little more frequently than the AV Node, so when all is normal, the heart is paced by the SA Node.

If a small heart attack kills the SA Node, then the AV Node would take over.

*My training is going on 30 years old, so please correct any mistakes I have made.