Which term refers to the innermost lining of a blood vessel?

Which term refers to the innermost lining of a blood vessel?

• A. Tunica intima
• B. Lumen
• C. Capillary
• D. Arteriole

Answer: (A)

The innermost lining of a blood vessel is the tunica intima. This layer faces the blood and is mainly composed of endothelial cells that form a smooth, friction-reducing surface and help regulate permeability and vascular tone. Beneath it sits connective tissue and, in larger vessels, the internal elastic lamina that separates the intima from the next layer. The lumen is the hollow space inside the vessel, not a lining, and capillaries or arterioles describe vessel types rather than the inner surface.

The innermost lining of a blood vessel is the tunica intima. This layer faces the blood and is mainly composed of endothelial cells that form a smooth, friction-reducing surface and help regulate permeability and vascular tone. Beneath it sits connective tissue and, in larger vessels, the internal elastic lamina that separates the intima from the next layer. The lumen is the hollow space inside the vessel, not a lining, and capillaries or arterioles describe vessel types rather than the inner surface.