Gastric Secretion Research Paper

The regulation of acid and pepsin secretion is associated with a balance of chemo-transmitters delivered to the gastric mucosa by pathways that facilitate stimulation and inhibition. The physiologic stimulation of acid secretion is divided into the cephalic, gastric, and intestinal. The main component of gastric secretion is HCL which is a product of the parietal cells. The parietal cells are epithelial cells that secrete HCL and essential factors. Parietal cells are located in the gastric glands in the lining of the fundus and in the body of the stomach. The capacity of the stomach to secrete HCL is related to amount of parietal cell. Parietal cells accept receptors for three stimulators of acid secretion which are Acetylcholine, Gastrin, …show more content…
Hydrogen ions are produced within the parietal cells by the dissociation of water. The hydroxyl ions formed combine with carbon dioxide to form a bicarbonate ion, which is a reaction catalyzed by carbonic anhydrase. Bicarbonate is transported out of the basolateral membrane in interchange for chloride. As the bicarbonate outflows into the blood this causes a slight elevation of blood pH known as the alkaline tide. The alkaline tide maintains intracellular pH in the parietal cells. Chloride and potassium ions are transported into the lumen of the canal by conductor channels that are important for the secretion of HCL. Hydrogen ions are pumped out of the cell and into the lumen where the hydrogen ions are exchanged for potassium by the proton pump. Potassium is recycled in the reaction and the buildup of osmotic hydrogen ions in the canal creates an osmotic gradient across the membrane. The result of this osmotic gradient leads to the outward diffusion of water (Bowen, …show more content…
Low concentrations of gastrin or acetylcholine will also result in weak stimulations of acid secretion. When low levels of histamine, gastrin and acetylcholine are present all together then acid secretion is increased. Pharmacologic antagonists of each of these molecules can block acid secretion for a certain amount of time. Histamine effects the parietal cell by activating adenylate cyclase which leads to an elevation of intracellular cyclic AMP and the activation of protein kinase A. The effect of PKA activation causes phosphorylation of cytoskeletal proteins involved in transport of the protein pump from cytoplasm to plasma membrane. When acetylcholine and gastrin are both bound this results in an increase of intracellular Ca concentrations (Bowen,