Pancreas

It is an endocrine and exocrine gland of the digestive system. The exocrine part’s pancreatic cells accumulate a viscous, clear secretion in their secretory vesicles – pancreatic juice. The pancreas secretes 0.5-1 liters of juice into the duodenum per day, with a pH of 7.3-8.7. Pancreatic juice contains NaHCO₃, which neutralizes chyme, making the pH of small intestinal juices weakly alkaline. The higher pH protects the intestinal mucosa from pepsin digestion (an enzyme in the stomach) and provides an optimal environment for the activity of intestinal and pancreatic enzymes. Water makes up to 99% of pancreatic juice, while dry substances make up about 1%. The main inorganic substances in pancreatic juice are: HCO^–₃, Cl^–, Na⁺, K⁺, Ca²⁺, etc. Organic substances include digestive enzymes: proteases (trypsin, chymotrypsin, carboxypeptidases, elastase, and collagenase), lipases, enzymes that break down polysaccharides, and nucleases. These enzymes are secreted into the duodenum as proenzymes. Here, they are converted into active enzymes – activated by partial proteolysis.

The endocrine part of the pancreas consists of 1-2 million Langerhans islets (1-2% of the pancreatic mass). The islets are made up of several types of cells: b (or B; up to 70%), α (or A; about 20%), δ (or D; 5-10%), and F cells (about 2%), which synthesize and release specific hormones into the bloodstream: insulin, glucagon, somatostatin, and pancreatic polypeptide (see Hormones).

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė