Final answer:
The pulmonary arteries branch profusely to feed into smaller arterioles and eventually to the pulmonary capillaries, where gas exchange occurs within the lung alveoli. The oxygenated blood then returns to the heart via the pulmonary veins.
Step-by-step explanation:
The pulmonary arteries are part of the pulmonary circuit and carry deoxygenated blood from the right ventricle of the heart to the lungs. These arteries branch profusely to feed into smaller arterioles and eventually to the pulmonary capillaries, where gas exchange occurs within the lung alveoli. The oxygenated blood then returns to the heart via the pulmonary veins.
Overall, the pulmonary arteries play a crucial role in transporting deoxygenated blood to the lungs for oxygenation and then returning oxygenated blood to the heart.