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Why does the right side of the heart pump blood to the lungs?

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Silhouette diagram of the human body highlighting the heart and major blood vessels, with labeled arteries in red and veins in blue to show the structure of the cardiovascular system. — Circulatory system Human circulatory system.

The right side of the heart pumps blood to the lungs to facilitate pulmonary circulation, a vital process for gas exchange.1

The primary purpose of this pathway is to replenish the blood's oxygen supply and remove carbon dioxide, which is a waste product of cellular metabolism. Specifically, the right ventricle pumps oxygen-poor blood into the pulmonary artery, which carries it to the lungs. Within the capillary networks surrounding the alveoli, carbon dioxide diffuses out of the blood to be exhaled, while oxygen from inhaled air enters the bloodstream.123

Once oxygenated, the blood returns to the left side of the heart to be distributed throughout the body via systemic circulation. Because this pulmonary circuit operates at lower pressures than the systemic circuit, it allows for efficient gas exchange without damaging the delicate tissues of the lungs.41