Veins generally carry deoxygenated blood back to the heart. This blood has traveled throughout the body, delivering oxygen and nutrients to tissues and picking up carbon dioxide and waste products. The heart then pumps this deoxygenated blood to the lungs, where it can be oxygenated.
However, there's one important exception: pulmonary veins. These veins carry oxygenated blood from the lungs back to the heart. This oxygenated blood is then pumped out to the rest of the body via the arteries.
So, while veins typically carry deoxygenated blood, the pulmonary veins are a crucial part of the circulatory system, carrying oxygenated blood back to the heart.
