Does the pulmonary artery in adults carry oxygen rich or oxygen poor blood?

The pulmonary arteries carry deoxygenated (O2-poor) blood from the heart to the lungs so the blood can be oxygenated. Remember that arteries and veins are not defined based on whether they carry O2-rich or O2-poor blood but rather the direction they carry blood. Arteries carry blood away from the heart and veins carry blood back to the heart.