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 thinnest layer in both veins and arteries is the innermost layer, the tunica intima. The tunica intima is made up of a single layer of cells, which are in direct contact with the blood that flows through the vessel. In arteries the thickest layer is the tunica media, the middle layer of the vessel tissue.