Bovine Pulmonary Artery
The pulmonary artery emerges above the right chamber of the heart, separating into two branches that enter the right and left lungs. In the lungs, the arteries further subdivide into smaller and smaller branches until they reach the capillaries in the pulmonary air sacs (alveoli). In the capillaries, blood takes up oxygen from the air breathed into the air sacs and releases carbon dioxide. It then flows into larger and larger vessels until it reaches the pulmonary veins. These veins open into the left atrium of the heart, which then pumps the freshly oxygenated blood to the rest of the body.