What type of blood vessel has thin walls and carries oxygen-depleted blood to the heart?

Veins are the type of blood vessel characterized by thin walls, which allows them to accommodate a larger volume of blood while maintaining lower pressure compared to arteries. The primary function of veins is to carry oxygen-depleted blood back to the heart. This is crucial for the circulatory system, as it ensures that blood can be reoxygenated in the lungs before being pumped out again to supply the rest of the body with oxygen-rich blood.

The thin walls of veins are composed of three layers: the tunica intima, tunica media, and tunica externa. However, the tunica media in veins is much thinner than that in arteries, which is why veins are less rigid and more flexible. Additionally, the presence of valves within many veins helps prevent the backflow of blood, ensuring a one-way transport to the heart.

While arteries carry oxygen-rich blood away from the heart and have thicker, more muscular walls to withstand high pressure, capillaries serve a different role as the site of gas exchange between blood and tissues. Arterioles are smaller branches of arteries but still differ from veins in their overall function and structure.