important role is to regulate the movement of materials into and out of cells. The phospholipid bilayer structure (fluid mosaic model) with specific membrane. proteins accounts for the selective permeability of the membrane and passive. and active transport mechanisms.
Structure of Blood Vessels a) Three distinct layers or tunics form the walls of blood vessels: ---The tunica interna (tunica intima) is the innermost layer.It contains the endothelium which is a continuation of the endocardial lining of the heart.tructure of Blood Vessels a) Three distinct layers or tunics form the walls of blood vessels: ---The tunica interna (tunica intima) is the innermost layer.
Its innermost layer is a simple squamous epithelium, called endothelium, which is continuous with the endocardial cells were regarded as little more than a passive barrier between the blood and the remainder of the vessel wall.hree tunics of blood vessel. The three structural layers of a generalized blood vessel from innermost to outermost are the tunica intima, tunica media and tunica adventitia.