The heart is a complex organ with a simple purpose – pump blood in and pump it out again.
It does this through an interconnected network of rectangular heart cells called cardiomyocytes that pump blood into the top of the heart (through the atria) and out through the ventricles at the bottom. Pacemaker cells on the heart keep it ticking away at 60 to 100 beats per minute, depending on the person’s basal heart rate.
