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

Only some cells in the heart are capable of beating continuously. This is called the sino-atrial node
This is the heart’s own little “brain” you can say, because it does not need continuous electricity impulse from the brain for every time it contracts. It gives it’s own signal to itself (however the sino atrial node is under regulation from brain which tells it how fast or slow to contract via the sympathetic and parasympathetic nerves)

These SA node cells are only slightly different from other heart cells in that the sodium movement inside the cell is not voltage gated, meaning there is no need of electrical impulse for ions to move in (rest of the heart cells get their current from SA node, SA node itself doesn’t get any current from outside)

Let me know if you need further clarification