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.
The heart is fundamentally a blood pump. It pumps blood from the right side of the heart to the lungs to pick up oxygen. The oxygenated blood returns to the left side of the heart. The left side of the heart then pumps blood into the circulatory system of blood vessels that carry blood throughout the body. The heart consists of four chambers. The two upper chambers are called atria and the two lower chambers are called ventricles.