What is the primary function of the pulmonary veins?

The primary function of the pulmonary veins is to carry oxygenated blood from the lungs to the heart. After oxygen is absorbed into the blood in the lungs, it is transported back to the left atrium of the heart through the pulmonary veins. This is essential for the circulatory system, as it allows the heart to pump this oxygen-rich blood to the rest of the body, supporting cellular respiration and overall metabolic processes.

In contrast, the other choices represent functions that are performed by different structures or within different systems. The pulmonary veins do not carry deoxygenated blood; that role is fulfilled by the pulmonary arteries. Regulation of blood pressure involves a complex interplay of various factors including hormones and other blood vessels, rather than the pulmonary veins directly. Additionally, while gas exchange occurs in the lungs, it is primarily facilitated by the alveoli and surrounding capillaries, not the pulmonary veins themselves.