Based on my understanding, heart is a double pump.
It is divided into two parts:
1.Left
2.Right.
The Right side of the heart is where it receives poor-oxygen blood(right atrium) from veins and pumps it to the lungs(right ventricle), it picks up oxygen and unloads or get rids of the carbon dioxide. The parts responsible for this is the right atrium and the right ventricle
The Left side of the heart receives rich-oxygen blood(left atrium) from the lungs and pumps(left ventricle) it to the rest part of the body.
