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 pulmonary circulation is a short loop from the heart to the lungs and back again, and the systemic circulation sends blood from the heart to all the other parts of our bodies and back again.The heart is the key organ in the circulatory system.