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 lamina propria which underlies the epithelium has a rich vascular and lymphatic network, which absorbs the digestive products, and there is a muscularis mucosae layer immediately at the base of the crypts. The lymphatic capillaries are called lacteals, and absorb lipids.The vascular capillaries are fenestrated to aid absorption. The muscularis externa layer contains two layers of smooth muscle, an inner circular and outer longitudinal, for continuous peristaltic activity of the small intestine.he lamina propria which underlies the epithelium has a rich vascular and lymphatic network, which absorbs the digestive products, and there is a muscularis mucosae layer immediately at the base of the crypts. The lymphatic capillaries are called lacteals, and absorb lipids.