Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Pancreas Chemical digestion in the small intestine relies on the activities of three accessory digestive organs: the pancreas, liver and gall bladder. The pancreas produces pancreatic juice, which contains digestive enzymes and bicarbonate, and delivers it to the duodenum. The digestive role of the liver is to produce bile and export it to the duodenum. The gall bladder primarily stores and releases bile. The soft, tadpole-shaped pancreas is a gland that is about 5-6 inches (13-15 cm) long and 1 inch (2.5 cm) thick. It lies posterior to the greater curvature of the stomach. The pancreas regions are described as the head, body, and tail. The head is next to the duodenum. The body lies behind the stomach. The tail is in contact with the spleen. The pancreas and common bile duct. This work by Cenveo is licensed under a Creative Commons Attribution 3.0 United States (http://creativecommons.org/licenses/by/3.0/us/). Pancreas Ducts The pancreas is important in digestion, because it produces pancreatic juice, a combination of fluid and digestive enzymes. Exocrine cells release this juice into small ducts that eventually unite to create two larger ducts that deliver pancreatic juice to the small intestine. The larger of these two ducts is the centrally locatedmain pancreatic duct (duct of Wirsung). In most individuals, this duct fuses with the common bile duct from the liver and gall bladder before entering the duodenum via the hepatopancreatic ampulla (ampulla of Vater), a dilated common duct. This ampulla opens on the major duodenal papilla, an elevation of the duodenal mucosa, which is situated approximately 4 inches (10 cm) inferior to the pyloric sphincter of the stomach. The smooth muscle hepatopancreatic sphincter controls the flow of pancreatic juice and bile into the small intestine. The second large pancreatic duct, the accessory duct (duct of Santorini) runs from the pancreas directly into the duodenum, approximately 1 inch (2.5 cm) above the hepatopancreatic ampulla. Pancreatic Islets In the pancreas, small clusters of glandular epithelial (secretory) cells surround the ducts. The exocrine structures of the pancreas contains 99 percent of the clusters that are called acini (singular - acinus). Cells of the acini secrete pancreatic juice. The endocrine part of the pancreas is made up of the remaining 1 percent of clusters, which are called pancreatic islets (islets of Langerhans). These cells produce the hormones pancreatic polypeptide, insulin, glucagon, and somatostatin. Insulin and glucagon are important in carbohydrate metabolism. Panreatic Acini and Exocrine Digestive Function Regulation of pancreatic secretion is the job of both hormones and the parasympathetic nervous system. The hormone secretin, whose secretion is stimulated by the presence of HCl in the intestine, provokes cells of the pancreatic duct to release bicarbonate-rich pancreatic juice. The presence of fats (and some proteins) in the intestine stimulates the secretion of the hormone cholecystokinin (CCK), which then stimulates the release enzyme-rich pancreatic juice and enhances the activity of secretin. As a result, much more bicarbonate-rich juice is released in the presence of both hormones. Parasympathetic regulation occurs mainly during the cephalic and gastric phases of gastric secretion, when vagal stimulation prompts the secretion of pancreatic juice.