The middle layer of a blood vessel, made up of smooth muscle fibers and a thick layer of elastic connective tissue, is the

The middle layer of a blood vessel, made up of smooth muscle fibers and a thick layer of elastic connective tissue, is the

• A. Tunica externa
• B. Tunica media
• C. Lumen
• D. Tunica intima

Answer: (B)

The middle layer of a blood vessel is the tunica media, and it is made up of circular smooth muscle fibers with a thick layer of elastic connective tissue. This setup lets the vessel constrict or relax—vasoconstriction and vasodilation—to regulate blood flow and help maintain blood pressure. The smooth muscle responds to autonomic signals and hormones, while the elastic components allow the wall to stretch and recoil with each heartbeat, helping to smooth out pressure changes. The inner layer is the tunica intima, lined by endothelium, and the outer layer is the tunica externa, which provides structural support. The lumen is simply the hollow passage through which blood flows.

The middle layer of a blood vessel is the tunica media, and it is made up of circular smooth muscle fibers with a thick layer of elastic connective tissue. This setup lets the vessel constrict or relax—vasoconstriction and vasodilation—to regulate blood flow and help maintain blood pressure. The smooth muscle responds to autonomic signals and hormones, while the elastic components allow the wall to stretch and recoil with each heartbeat, helping to smooth out pressure changes. The inner layer is the tunica intima, lined by endothelium, and the outer layer is the tunica externa, which provides structural support. The lumen is simply the hollow passage through which blood flows.