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 body's circulatory system has three distinct parts: pulmonary circulation, coronary circulation and systemic circulation. Pulmonary circulation is the movement of blood from the heart, to the lungs, and back to the heart again. Coronary circulation refers to the movement of blood through the tissues of the heart. Systemic circulation supplies nourishment to all our body tissues. Each of our circulatory systems works independently.