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.
Pulmonary circulation is the movement of blood though the right side of the heart, to the lungs, and then back through the left side of the heart. The âlub dubâ you hear when using a stethoscope is the sound of the ventricles contracting and the heart valves closing during this circulation process.