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 epidermis or outer layer is the active growing layer of the skin, which provides a tough outer layer of cells that protect us .It does not contain blood vessels and is nourished by a process called diffusion, in which fluid coming from the blood vessels in the next lower layer, the dermis. Source(s):ust to point out, you asked which part of the DERMIS does not contain any blood vessels. The epidermis is avascular as the answers above have mentioned, but the epidermis is not part of the dermis. The dermis and epidermis are two separate and distinct parts of the skin.