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The bicarbonate ion (hydrogencarbonate ion) is an anion with the empirical formula HCO − 3 and a molecular mass of 61.01 daltons; it consists of one central carbon atom surrounded by three oxygen atoms in a trigonal planar arrangement, with a hydrogen atom attached to one of the oxygens. It is isoelectronic with nitric acid HNO 3.
Most of the carbonic acid then dissociates to bicarbonate and hydrogen ions. The bicarbonate buffer system is an acid-base homeostatic mechanism involving the balance of carbonic acid (H 2 CO 3), bicarbonate ion (HCO − 3), and carbon dioxide (CO 2) in order to maintain pH in the blood and duodenum, among other tissues, to support proper ...
The alkaline tide is neutralised by a secretion of H + into the blood during HCO 3 − secretion in the pancreas. [2] Postprandial (i.e., after a meal) alkaline tide lasts until the acids in food absorbed in the small intestine reunite with the bicarbonate that was produced when the food was in the stomach. Thus, alkaline tide is self-limited ...
The ductal pancreas network originates from the central pancreatic duct—this main duct with the bile duct opens into the duodenum. The ductal cells of the main pancreatic duct are bound by connective tissue and produce a columnar epithelium. [3] Interlobular ducts originate from the main pancreatic duct and connect the various pancreatic lobes.
The pancreas also receives autonomic innervation. The blood flow into pancreas is regulated by sympathetic nerve fibers, while parasympathetic neurons stimulate the activity of acinar and centroacinar cells. Pancreatic secretion is an aqueous solution of bicarbonate originating from the duct cells and enzymes originating from the acinar cells.
Aqueous pancreatic secretions from pancreatic duct cells contain bicarbonate ions which are alkaline and help with the bile to neutralise the acidic chyme that is churned out by the stomach. The pancreas is also the main source of enzymes for the digestion of fats and proteins.
The enzyme carbonic anhydrase catalyses the reaction between carbon dioxide and water to form carbonic acid. This acid immediately dissociates into hydrogen and bicarbonate ions. The hydrogen ions leave the cell through H + /K + ATPase antiporter pumps. At the same time, sodium ions are actively reabsorbed [citation needed].
Water is a very minor source of hydrogen ions in comparison to carbonic acid. Carbonic acid is formed from carbon dioxide and water by carbonic anhydrase. The bicarbonate ion (HCO 3 −) is exchanged for a chloride ion (Cl −) on the basal side of the cell and the bicarbonate diffuses into the venous blood, leading to an alkaline tide phenomenon.