 Dear students, in this topic we shall discuss the features of absorptive epithelium of small intestine. Absorption is a phenomena through which the digested nutrients present in the lumen of the elementary canal are absorbed into the blood to be transported and to reach the tissues and cells of the body. Most of the absorption occurs by crossing the epithelial lining of the helium part of small intestine. The epithelial lining of the small intestine and especially of the helium part is specialized for absorptive functions. This epithelial lining has increased surface area for absorption and has a rich supply of transport system. These two features make it a specialized surface for absorption of products of digestion. First we shall discuss the adaptations of small intestine to increase the surface area for absorption. The surface area for absorption is increased by the evolution and development of certain anatomical features. For example, intestinal folds will lie, epithelial cells on will lie and micro will lie. We shall discuss these features one by one. The intestinal folds, if we see the luminal wall of small intestine, it has numerous circular folds. These folds provide increased surface for the placement of will lie which substantially increase the surface area for absorption. Will lie are finger-like projections which are present in thousands of numbers on the circular folds. Hervillus is a small structure which is about 1 mm in length and due to its presence, the appearance of the inside of the intestine becomes velvety. If we open the intestine and see the surface, it appears velvety because of the presence of will lie on it. Each will has a covering of epithelial cells. These epithelial cells form the actual absorptive surface of small intestine. The substances absorbed are actually absorbed in these epithelial cells. The micro will lie, many thousand closely packed cylindrical processes are present on the apical surface of each epithelial cell. Epithelial cells membrane is not smooth. In fact, one side of it, the luminal side is where the epithelial cell faces the intestinal lumen. On that surface, there are micro will lie in the number of thousands. Each micro will lie is about 0.5 to 1.5 micrometer long and is about 0.1 micrometer wide. These structures increase the absorptive surface of each epithelial cell thousands of times. Dear students, these micro will lie have such a large number that when they take side by side, the appearance of the intestinal epithelium becomes brush-like. This is because a special term is used for intestinal lining, that is, brush border. That is because of the presence of micro will lie. Micro will lie increase the total capacity for nutrient absorption. Dear students, now we shall discuss the supply of transport system to the will lie and to the small intestine. A willis has a network of blood vessels inside it. These blood vessels consist of arterioles, capillaries and venules. The entire network is present in the center of a willis. Apart from this, a willis also contains a network of lymph vessels. In lymphatic vessels, the biggest one is a central lactile that supplies every will lie. Nutrients which are taken up by the epithelial cells are transferred to blood and lymph vessels inside the will lie. Central lactile can take up comparatively larger particles as compared to the blood circulatory capillaries. Dear students, overall the intestinal epithelium which has intestinal folds, will lie and micro will lie, they collectively increase the surface area more than 500 times. Total area for absorption of the small intestine in humans is about 200 to 300 meter squares. If we look at the cylindrical area of the small intestine, that is only 0.4 meter squares. This is a substantial increase which is about 500 times.