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.
Each beat of the heart pumps blood into both the pulmonary and system circulation system. This provides a continuous flow of oxygenated blood to the body's organs, tissue and cells. It also provides a continuous flow of deoxygenated blood to the lungs where the red blood cells pick up oxygen.