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.
The three structural layers of a generalized blood vessel from innermost to outermost are the tunica intima, tunica media and tunica adventitia.Modification of this basic design account for the five types of blood vessels and the structural and functional differences among the various vessel types.The tunica intima forms the inner lining of blood vessel and direct contact with the blood as it flows through the lumen of the vessel.he tunica interna (intima) forms the inner lining of a blood vessel and is in direct contact with the blood as it flows through the lumen, or interior opening, of the vessel.