Final answer:
The tunica media's two main components are smooth muscle and elastic fibers in the connective tissue, enabling vessel diameter regulation and maintaining blood pressure.
Step-by-step explanation:
The two main components of tunica media are smooth muscle and connective tissue, which is primarily made up of elastic fibers. The smooth muscle allows for the regulation of the vessel's lumen diameter through processes such as vasoconstriction and vasodilation. Connective tissue provides structure and support and includes both collagenous fibers and a high concentration of elastic fibers that facilitate the vessel’s ability to stretch and maintain blood pressure.