Arteries are vessels that carry blood away from the heart. The pulmonary artery transports blood from the heart to the lungs. While most major arteries branch off from the aorta, the main pulmonary artery extends from the right ventricle of the heart and branches into left and right pulmonary arteries. The left and right pulmonary arteries extend to the left lung and right lungs.
The pulmonary arteries are unique in that unlike most arteries which carry oxygenated blood to other parts of the body, the pulmonary arteries carry de-oxygenated blood to the lungs. After picking up oxygen, the oxygen rich blood is returned to the heart via the pulmonary veins.