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Double circulation refers to a circulatory system in which blood passes through the heart twice during one complete circuit of the body. This type of circulation is characteristic of mammals, birds, and reptiles, including humans.
In this system, blood undergoes two distinct circuits, known as pulmonary circulation and systemic circulation.
- Pulmonary Circulation: Deoxygenated blood returns to the right atrium from the body and then passes into the right ventricle. From there, it is pumped to the lungs through the pulmonary artery. In the lungs, blood releases carbon dioxide and picks up oxygen, becoming oxygenated. This oxygen-rich blood returns to the heart, entering the left atrium via the pulmonary veins.
- Systemic Circulation: Oxygenated blood flows from the left atrium into the left ventricle, which then pumps it out to the body through the aorta, the largest artery. Throughout the body, tissues receive oxygen and nutrients from the blood and release carbon dioxide and waste products into it. Deoxygenated blood, carrying waste, returns to the heart through systemic veins, entering the right atrium to complete the circulation cycle.
Double circulation efficiently ensures oxygen delivery to tissues and waste removal, supporting the body’s metabolic needs.
