What is the primary function of veins?

The primary function of veins is to carry blood back to the heart. Veins are an integral component of the circulatory system, responsible for transporting deoxygenated blood from various parts of the body back to the heart, where it can be pumped to the lungs for oxygenation.

Veins have features such as one-way valves and a thinner wall structure compared to arteries, allowing them to facilitate the return flow of blood despite lower pressure than in arteries. By serving as conduits for deoxygenated blood, veins help maintain proper blood circulation and volume in the cardiovascular system.

While options relating to oxygen-rich blood, immune response, or nutrient absorption reference important physiological processes, they do not pertain to the main role of veins. Arteries are primarily responsible for circulating oxygen-rich blood from the heart to the body, while the immune response is mainly mediated by the lymphatic system, and nutrient absorption occurs in the digestive system. Thus, the accurate depiction of veins’ role is centered on their function in returning blood to the heart.