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.
Veins: It carries blood from the capillaries back towards the heart. They have much slighter walls compared to arteries. Sinusoids: They are very small vessels located within the bone marrow, liver and spleen. Layers of Blood Vessels. Both arteries and veins consist of three layers. Tunica Intima: It is one of the innermost and thinnest layers of arteries and veins. It comprises of endothelial cells. They are in direct contact with the flow of blood. It intern consists of three layers. I.e. Inner Layer, Middle Layer, and Outer Layer.