What is the main role of veins?

The main role of veins in the circulatory system is to return blood to the heart after it has delivered oxygen to the body's tissues. This function is essential for maintaining proper circulation and ensuring that deoxygenated blood is efficiently transported back to the heart to be re-oxygenated in the lungs.

Veins have thinner walls compared to arteries and often contain valves that prevent the backflow of blood, which is particularly important as they work against gravity, especially in the limbs. This ability to return blood to the heart is vital for sustaining the overall function of the circulatory system and ensuring that oxygen is continuously supplied to the body's tissues.

While veins play a role in returning blood, arteries carry oxygen-rich blood away from the heart, and while hormones are circulated throughout the body, this is a function primarily associated with the endocrine system rather than the primary role of veins. Additionally, supplying nutrients to the heart is mainly the responsibility of coronary arteries.