The heart has a natural pacemaker which means that it goes for the lifetime if it does not get disabled by some causes, and it sends out electrical impulses on the top atrium, and generates a pump on the blood onto the ventricle. Then, the electrical impulse will be conducted to the ventricle through a form of “junction box” called the AV node(the middle of the heart).
I think the function of the heart and the brain is the most interesting part of the human body. It is just so amazing that living organs can actually think, and command our functions of our body. Also, the heart is where it generates blood with such complicated blood vessels. Not just for humans, but all living being that has a heart could pump forever while they are living and you would not notice a lot that your heart is pumping constantly, even when your sleeping.