The pancreas is an important accessory digestive organ since it is responsible for the production of enzyme that breaks down literally all categories of foodstuffs. The broken down foods are then delivered to the duodenum.
The name pancreas literally means “all flesh”. It is described as a tadpole-shaped, soft gland that extends across our abdomen. The pancreas can be found deep in the greater curvature of the stomach.
The exocrine product of the pancreas, known as the pancreatic juice, travels from the pancreas via the main pancreatic duct located centrally. The two accessory ducts, the pancreatic and the bile ducts, fuse together, forming the hepatopancreatic ampulla.
The Composition of Pancreatic Juice
Every day, the pancreas creates about 1200 to 1500 ml of clear pancreatic juice. This pancreatic juice is mostly made up of water, enzymes and electrolytes. The enzymes found in the pancreatic juice came from the acinar cells and the bicarbonates ions are from the epithelial cells. The presence of bicarbonate ions makes the juice alkaline, having a pH of about 8. The high pH of the pancreatic juice also serves another purpose, and that is to neutralize the already acidic chyme that enters the duodenum. Furthermore, it provides the perfect environment for pancreatic and intestinal enzymes to function optimally.
The pancreas also produces proteases or protein-digesting enzymes. The protease that the pancreas releases are still in its inactive form and is activated when it reaches the duodenum. This action prevents self-digestion of the pancreas.
Regulation of Pancreatic Secretion
The parasympathetic nervous system and other significant hormones help in regulating the secretion of pancreatic juice. Two significant hormones come directly from the small intestines. As the food enters the alimentary canal, the vagal nerve is stimulated. Upon stimulation, it influences the subtle release of pancreatic juice and initiates weak contractions of the gallbladder. After the food has been mechanically broken down, churned and mixed in the stomach, it enters the duodenum as an acidic chyme. The presence of this acidic chyme then causes the enteroendocrine cells found in the walls of the duodenum to release secretin. Another hormone, cholecystokinin, is released if there is the presence of a fatty, protein-rich chyme.
The two hormones then enters the bloodstream and heads towards the pancreas. When it reaches the pancreas, the cholecystokinin then influences the pancreas to release an enzyme-rich pancreatic juice. On the other hand, secretin influences the release of bicarbonate-rich pancreatic juice.
As a regulatory mechanism, the amount of HCl produced in the stomach is close to the amount of bicarbonate produce by the pancreas.