What is Intrinsic Factor related to-

o Vitamin B12 (cyanocobalamine) is absorbed in the ileum Q Intrinsic factor (of the castle) is necessary for its absorpon Q . IF is secreted by oxync cells of stomach. In the lumen of the small intesne, IF forms acomplex with vitamin B12. Vitamin B12-IF complex binds with a specific receptor on the surface of the epithelial cells of the ileum Q . Vitamin B12 is transported into the enterocytes leaving behing IF at the brush border, Water and electrolytes are mainly absorbed in the jejunum. IMPORTANT FACTS ABOUT ABSORPTION  Absorption pattern of duodenum and jejunum is almost the same. Following mentioned nutrients are absorbed both in duodenum and jejunum, however, their absorption differs quantitatively : - 3. Mainly absorbed in duodenum : - Calcium, Iron Q . 4. Mainly absorbed in jejunum : - Amino acids, water soluble vitamins (B1, B2. B3, B5, B6, Biotin and Vitamin C), fat soluble vitamins (A, E, D, K), Fats Q (Triglycerides, Cholesterol), Sugars (monosaccharides, disaccharides), water, NaCl (electrolytes Q ). o Following are absorbed in the Ileum2 : - Bile & bile salts Q . Vitamin B12 Q, Na + , water. □ Vitamin B12, (cyanocobalamine) is absorbed in the ileumQ . Intrinsic factor (of the castle) is necessary for its absorption Q IF is secreted by oxyntic cells of the stomach. In the lumen of the small intestine, IF forms a complex with vitamin B12. Vitamin B12-IF complex binds with a specific receptor on the surface of the epithelial cells of the ileum Q Vitamin B12 is transported into the enterocvtes leaving behing IF at the brush border. o Following are absorbed in the colon : - Water and electrolytes Q (Na + & Cl ) Water and electrolyte absorption o Water and electrolytes need no digeson and are absorbed as such. There is approximately 9 liters of water input: Ingested water : 2.0 litres. Saliva: 1.5 litres, gastric juice : 2.5 litres, bile 0.5 litre, pancreac juice : 1.5 litres, and smalt intesne secreons 1.0 litre. Out of these 9 litres, 7.7 litres (85%) is absorbed in small intesne and 1.0 - 1.5 litres (5-10%) is absorbed in large intesne (colon). Total 8.8 litres of water is absorbed 2 and 0.2 litre is excreted in feces. In small intesne., most of the water is reabsorbed in the jejunum Q . o Na + and Cl are also absorbed maximally in jejunum with some absorption in the colon.