Which layer lines the interior lumen of a blood vessel?

Which layer lines the interior lumen of a blood vessel?

• A. Aorta
• B. Phlebitis
• C. Varicose veins
• D. Tunica intima

Answer: (D)

The inner lining that comes into contact with blood is the tunica intima. This innermost layer sits directly against the lumen and is made mainly of endothelial cells that create a smooth surface to reduce friction and help regulate blood flow and vessel function. The vessel wall as a whole has three layers: intima, media (smooth muscle), and adventitia (outer connective tissue). The other options describe a specific vessel (the aorta) or conditions affecting veins (phlebitis, varicose veins), not the lining itself. So the correct concept is the tunica intima.

The inner lining that comes into contact with blood is the tunica intima. This innermost layer sits directly against the lumen and is made mainly of endothelial cells that create a smooth surface to reduce friction and help regulate blood flow and vessel function. The vessel wall as a whole has three layers: intima, media (smooth muscle), and adventitia (outer connective tissue). The other options describe a specific vessel (the aorta) or conditions affecting veins (phlebitis, varicose veins), not the lining itself. So the correct concept is the tunica intima.