is cleaved with pancreatic enzymes, releasing the intact vitamin B12. Intrinsic factor (IF) produced by the parietal cells then binds Vitamin B12, creating a Vit. B12-IF complex. This complex is then absorbed at the terminal portion of the ileum. Mucin: The stomach has a priority to destroy the bacteria and viruses using its highly acidic environment but also has a duty to protect its own lining from its acid. The way that the stomach achieves this is by secreting mucin and bicarbonate via its mucous cells, and also by having a rapid cell turn-over. Gastrin: This is an important hormone produced by the "G cells" of the stomach. G cells produce gastrin in response to stomach stretching occurring after food enters it, and also after stomach exposure to protein. Gastrin is an endocrine hormone and therefore enters the bloodstream and eventually returns to the stomach where it stimulates parietal cells to produce hydrochloric acid (HCl) and Intrinsic factor (IF). Of note is the division of function between the cells covering the stomach. There are four types of cells in the stomach: Parietal cells: Produce hydrochloric acid and intrinsic factor. Gastric chief cells: Produce pepsinogen. Chief cells are mainly found in the body of stomach, which is the middle or superior anatomic portion of the stomach. Mucous neck and pit cells: Produce mucin and bicarbonate to create a "neutral zone" to protect the stomach lining from the acid or irritants in the stomach chyme. G cells: Produce the hormone gastrin in response to distention of the stomach mucosa or protein, and stimulate parietal cells production of their secretion. G cells are located in the antrum of the stomach, which is the most inferior region of the stomach. Secretion by the previous cells is controlled by the enteric nervous system. Distention in the stomach or innervation by the vagus nerve (via the parasympathetic division of the autonomic nervous system) activates the ENS, in turn leading to the release of acetylcholine. Once present, acetylcholine activates G cells and parietal cells. Pancreas Pancreas is both an endocrine and an exocrine gland, in that it functions to produce endocrinic hormones released into the circulatory system (such as insulin, and glucagon), to control glucose metabolism, and also to secrete digestive/exocrinic pancreatic juice, which is secreted eventually via the pancreatic duct into the duodenum. Digestive or exocrine function of pancreas is as significant to the maintenance of