What is the purpose of veins in the circulatory system?

Veins serve a crucial role in the circulatory system by transporting deoxygenated blood back to the heart. After the oxygen has been delivered to the tissues and organs by the arteries, the blood, now lacking in oxygen and rich in carbon dioxide and other waste products, enters the venous system. This return pathway ensures that the deoxygenated blood is sent back to the heart, where it can then be pumped to the lungs for reoxygenation.

This function is essential for maintaining proper circulation and ensuring that the body's tissues are supplied with fresh oxygen and ready for removing waste products. The consideration of pressure regulation and nutrient absorption pertains to other functions within the circulatory system that are not the primary roles of veins.