Pulmonary circulation carries blood to and from the lungs. They include the pulmonary artery (aorta) and its branches to the capillaries in the lungs, as well as the veins that drain those capillaries.
The pulmonary arteries carry blood, which is low in oxygen from the right ventricle, while the pulmonary veins carry blood high in oxygen from the lungs into the left atrium. This circuit functions to eliminate carbon dioxide from the blood and replenish its supply of oxygen.

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