MEDICAL PHYSIOLOGY

Detailed explanation-1: -The innermost layer, the tunica intima (also called tunica interna), is simple squamous epithelium surrounded by a connective tissue basement membrane with elastic fibers. The middle layer, the tunica media, is primarily smooth muscle and is usually the thickest layer.

Detailed explanation-2: -The innermost layer of the vein is the tunica intima. This layer consists of flat epithelial cells. These cells allow fluid to flow smoothly and are interspersed with valves that ensure the flow continues in one direction. This continuous layer of epithelial cells holds cells and fluid within the vessel lumen.

Detailed explanation-3: -The tunica intima is the innermost layer of arteries and veins and represents a tissue layer found in all parts of the circulatory system. In the capillaries, the tunica intima is also responsible for the exchange of gases and nutrients between the blood and surrounding tissues.

Detailed explanation-4: -The tunica externa (New Latin “outer coat"), also known as the tunica adventitia (New Latin “additional coat"), is the outermost tunica (layer) of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and, in arteries, is supported by external elastic lamina.