Pulmonary Arteries: The pulmonary arteries carry deoxygenated blood from the heart to the lungs. These are the only arteries that carry deoxygenated blood. It begins at the base of the right ventricle then branches into two pulmonary arteries (left and right), which deliver de-oxygenated blood to the corresponding lung.
On the ventral surface of the heart passing dorsally and to the left is the large pulmonary artery. It originates in the right ventricle. Try tracing it its two branches to the lungs.