DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules.
The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the human heart there is one atrium and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle.
Circulation describes the process of blood moving from the heart (the pump), out to the brain, major organs, then limbs all using the arterial blood vessels, and through the venous blood system (uses veins) back to the lungs and heart.