1. Hormone secretion: Pancreatic islets of Langerhans consist of a cluster of 100,000 cells.
(i) Alpha cells: 20% of human islets are alpha cells. It secretes glucagon hormone and increases blood glucose levels.
(ii) Beta cells: 50-70% of human islets are beta cells. It secretes the hormone insulin and lowers blood glucose levels. Lack of this hormone causes diabetes mellitus.
(iii) Delta cells: 10% of human islets are delta cells. It secretes the hormone somatostatin which regulates the secretion of alpha and beta cells.
(iv) Gamma cells: It secretes pancreatic polypeptide.
2. Enzyme secretion: Amylase, trypsin and lipase are secreted from this gland. Besides, chymotrypsin, collagenase, erepsin, elastase, phospholipase, esterase, carboxypeptidase, aminopeptidase, dipeptidase, tripeptidase etc. are secreted from this gland.
3. Salt secretion: Bicarbonate salt is secreted from this gland. It removes stomach discomfort.
4. Water balance: It regulates water balance in the body.
5. Acid-base balance: It maintains acid-base balance in the body.