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.
Endothelial cells (Fig.1) line the inside of every blood vessel in the body. They form a one-cell-thick layer called the endothelium, which is also found on the inner walls of the heart chambers and lymphatic vessels (which carry excess blood plasma around the body). The endothelium is very extensive.