Describe double circulation in human body

The heart receives deoxygenated blood from different parts of the body, and it pumps this blood to the lungs. The oxygenated blood from the lungs returns to the heart, which is pumped again into different parts of the body by the heart. Thus, the blood passes twice through the heart making one complete round through the body. This is called double circulation.

Pulmonary and systemic circulation

The pulmonary circulation pertains to lungs. The blood flows from the right ventricle to the lungs. Pulmonary veins collect oxygenated blood from the lungs and carry it back to the heart (left auricle). 

The systemic circulation pertains to the major circulation of the body. The aorta receives the blood from the left ventricle and sends it to the various parts of the body. Veins collect the deoxygenated blood from the body parts and pour it back into the right auricle.

A type of blood circulation system in which the blood flows through the heart twice. In this type of circulation, the pulmonary circulation is separate from the systemic circulation. Supplement In this circulation, the heart consists of: the right side that pumps deoxygenated blood into the pulmonary section and the left side that pumps oxygenated blood into the systemic circulation. This is common among mammals and birds. This is in contrast to animals that have only one circulation system such as fish.