Intrinsic factor is a glycoprotein produced by the parietal cells of the stomach. It is necessary for the absorption of vitamin B12 later on in the small intestine. A glycoprotein is a macromolecule composed of a protein and a carbohydrate (a sugar). ... Parietal cells (also called oxyntic cells) are cells located in the stomach epithelium. ... The stomach (Gaster) In anatomy, the stomach (in ancient Greek στόμαχος) is an organ in the gastrointestinal tract used to digest food. ... Cobalamin or vitamin B12 is a chemical compound that is also known as cyanocobalamine. ...

Upon entry into the stomach, vitamin B12 becomes bound to one of two B12 binding proteins present in gastric juice. In the less acidic environment of the small intestine, these proteins dissociate from the vitamin, enabling it to bind to intrinsic factor and enter the portal circulation through a receptor in the ileal mucosa specific for the B12-intrinsic factor complex. The portal vein is a major vein in the human body draining blood from the digestive system and its associated glands. ... Grays Fig. ... The mucous membranes (or mucosa) are linings of ectodermic origin, covered in epithelium, that line various body cavities and internal organs. ...

In pernicious anemia, an autoimmune disease, autoantibodies directed against intrinsic factor or parietal cells themselves lead to an intrinsic factor deficiency, malabsorption of vitamin B12, and subsequent megaloblastic anemia. Atrophic gastritis can also cause intrinsic factor deficiency and anemia through damage to the parietal cells of the stomach wall. Pancreatic exocrine insufficiency can interfere with normal dissociation of vitamin B12 from its binding proteins in the small intestine, preventing its absorption via the intrinsic factor complex. Pernicious anemia refers to a type of autoimmune anemia. ... Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. ... An autoantibody is a protein manufactured by the immune system that is directed against one or more of the hosts own proteins. ... Megaloblastic anemia is anemia resulting from a deficiency of vitamin B12 and folic acid. ... Atrophic gastritis is generally caused by an overgrowth of bacteria It can lead to inflammation decrease secretion of hydrochloric acid decreased secretion or production of pepsin Categories: Medicine stubs ... The pancreas is a retroperitoneal organ that serves two functions: exocrine - it produces pancreatic juice containing digestive enzymes endocrine - it produces several important hormones Anatomy The pancreas is a retroperitoneal organ located posterior to the stomach on the posterior abdominal wall. ... Exocrine gland refers to glands that secrete their products via a duct. ...