Complex sentence: The pulmonary arteries carry blood to the lungs, where red blood cells release carbon dioxide and pick up oxygen during respiration Oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle.
Split into simpler sentences: The pulmonary arteries carry blood to the lungs, where red blood cells release carbon dioxide and pick up oxygen during respiration. The oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle.