Pancreatic function
Pancreatic function; normal pancreatic function
Normal pancreatic function
Introduction
The pancreas is specialized organ that is involved in the digestive process. The pancreas is composed of two morphologically and functionally different tissues including endocrine tissue and exocrine tissue.
The pancreas is a large gland has endocrine and exocrine functions which are responsible for pancreatic secretion. The pancreatic secretions can be divided into endocrine and exocrine components.
Pancreas endocrine function
The endocrine functions of the pancreas include production of insulin and glucagon which are involved in carbohydrate metabolism.
The endocrine consists of the islets of Langerhans composed of at least four different cell types. The islet cells secrete four hormones into the blood involving insulin, glucagon, gastrin, and somatostatin.
The glucagon and insulin control the plasma glucose concentration.
Pancreas exocrine function
The exocrine pancreatic tissues secrete about 1.5–2 L/day of fluid which is rich in digestive enzymes into the duodenum.
The exocrine pancreatic secretion made up of two components:
(a) Alkaline pancreatic fluid:
This digestive fluid is produced by pancreatic acinar cells (grapelike clusters), which is clear, colorless, and watery, with an alkaline pH (8.3) due to high concentration of sodium bicarbonate.
Alkaline pancreatic fluid neutralizes gastric aid secretion and giving optimal environment for activity of duodenal digestive enzymes.
Pancreatic fluid has about the same concentrations of serum potassium and sodium.
(b) The pancreas digestive enzymes
(1) Proteolytic enzymes which are trypsin, chymotrypsin, elastase, collagenase, leucine aminopeptidase, and some carboxypeptidases.
(2) Enzymes of lipids digestion involving lipase and lecithinase
(3) Enzymes of carbohydrate digestion including pancreatic amylase.
(4) Several nucleases (ribonuclease), which separate the nitrogen-containing bases from their sugar-phosphate strands.
Pancreas secretions control
Pancreatic activity is under both nervous and endocrine control:
(1 (1) Vagus nerve branches can cause secretion of a small amount of pancreatic fluid in state of food is smelled or seen, and when food reaches the stomach.
(2 (2) Hormonal control of pancreatic secretion
The gut peptides control pancreatic secretions and are released from duodenal in response to high pH or presence of food
Most pancreatic secretions are under secretin and cholecystokinin (CCK) control.
Secretin is synthesized in response to the acidic gastric juice reaching the duodenum. It can also affect gastrin activity in the stomach.
Secretin stimulates the release of high volume of alkaline fluid (bicarbonate-rich fluid).
Cholecystokinin (CCK) is produced by the cells of the intestinal mucosa in the presence of fats or amino acids in the duodenum
Cholecystokinin (CCK) is responsible for release of enzymes from the acinar cells by the pancreas into the pancreatic fluid
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