Which human blood vessel carries deoxygenated blood from the heart to the lungs?

The pulmonary artery carries deoxygenated blood from the human heart to the lungs.

It begins at the right ventricle, where the pulmonary trunk leaves the heart and divides into right and left pulmonary arteries. These vessels carry blood to the corresponding lungs, where branches become smaller arteries and capillaries surrounding the alveoli. Carbon dioxide leaves the blood and oxygen enters it across the thin respiratory surface.

The pulmonary artery is an important exception to the simplified rule that arteries carry oxygen-rich blood. In anatomy, an artery is defined by the direction of flow away from the heart, not by oxygen content. The pulmonary artery therefore carries oxygen-poor blood, while the pulmonary veins carry oxygen-rich blood back to the left atrium.

The pulmonary trunk is separated from the ascending aorta by the pulmonary valve and the heart’s great-vessel arrangement. Pressure in the pulmonary circulation is normally lower than pressure in the systemic circulation, because it serves the nearby lungs rather than the entire body.