ANATOMY

Detailed explanation-1: -arteries. The tunica media, or middle coat, is made up principally of smooth (involuntary) muscle cells and elastic fibres arranged in roughly spiral layers. The outermost coat, or tunica adventitia, is a tough layer consisting mainly of collagen fibres that act as a supportive element.

Detailed explanation-2: -The middle layer, the tunica media, is primarily smooth muscle and is usually the thickest layer. It not only provides support for the vessel but also changes vessel diameter to regulate blood flow and blood pressure.

Detailed explanation-3: -The tunica media is composed chiefly of circumferentially arranged smooth muscle cells. Again, the external elastic lamina often separates the tunica media from the tunica adventitia. Finally, the tunica adventitia is primarily composed of loose connective tissue made up of fibroblasts and associated collagen fibers.

Detailed explanation-4: -The tunica media is the middle portion of the vessel wall and contains smooth muscle cells and connective tissue, whereas the tunica adventitia is composed of connective tissue that is often continuous with the surrounding soft tissues.

Detailed explanation-5: -The vein wall consists of three layers: The tunica intima, the tunica media and the tunica adventitia. The innermost layer of the vein is the tunica intima.