The pulmonary artery carries deoxygenated (impure) blood from the heart to the lungs where blood gets oxygenated and is returned back to the heart via the pulmonary vein.

The pulmonary arteries are the only arteries in your body that carry oxygen-poor (deoxygenated) blood. The main pulmonary artery (pulmonary trunk) leaves your right ventricle at your pulmonary valve.