Pancreas is a dual gland composed of two portions, an exocrine portion having cells producing enzymes required for digestion of food and Endocrine portion having groups of cells producing hormones required for metabolism and homeostasis.
As a digestive gland it plays a very important role in the process of digestion by possessing the most potent or powerful enzymes required for digestion of all types of food molecules namely carbohydrates, proteins, fats and nucleic acids.
The pancreatic juice secreted by the pancreatic exocrine glands reaches the intestine through the pancreatic duct (duct of wirsung) which usually joins the bile duct before opening into the first part of the duodenum. It is a clear, colourless liquid, containing some salts and sodium bicarbonate apart form enzymes.
As soon as food enters duodenum, a series of neurogenic and hormonal mechanism’* come into play and maintain a steady secretion of these fluids into the duodenum. These secretions mix with the acid chyme released from the stomach’ in the duodenum. The salts and bicarbonates neutralise and alkalize the acid chyme whereas the enzymes work upon the complex food molecules converting them into smaller molecules which are later on acted upon by intestinal juice enzymes converting them into absorbable forms.
The pancreatic digestive action can be summarized as follows :
(1) Carbohydrases (carbohydrate splitting):
Pancreatic amylase acts on polysaccharides starch (plant origin) and glycogen (animal origin) converting these into disaccharide molecules, namely maltose.
(2) Proteases (Protein-splitting):
Trypsin, Chymotrypsin (Endopeptidases) act on native proteins splitting them into pro-teoses, peptones and polypeptide molecules.
Carboxypeptidase (exopeptidase) act on proteins, peptones and polypeptides splitting them into tripeptides, dipeptides and amino acids.
(3) Pancreatic lipase:
act on fats emulsified by brie salts splitting them into glycerol, fattyacids and monoglycerides.
(4) Nucleases:
Ribonuclease and deoxyrib-onucleases – splitting nucleic acids (RNA & DNA) into simple nucleotides of respective types. These are later acted upon by nucle-otidases, splitting them into nucleosides of RNA & DNA and PO
