Location: The head of the pancreas lies in the curve of duodenum, the body crosses the midline of the body, and the tail extends towards the hilum of the spleen.
Function: secretion of enzymes:
Composition: epithelium of pyramidal serous acinar cells rich of acidophilic zymogen granules with inactive enzymes or proenzymes.
Function: secretion of large volume of fluid rich in sodium and bicarbonate.
Location: islets of Langerhans are scattered throughout the pancreas, constitute about 1-2% of the volume, and are most numerous in the tail.
Composition and function: polygonal endocrine cells are arranged in short, irregular cords that are profusely invested with a network of fenestrated capillaries.
Function: secrete insulin that lowers blood glucose. Its principal effects are on liver, skeletal muscle, and adipose tissue. Insulin stimulates uptake of glucose from circulation, utilization and storage of glucose by all cells, phosphorylation of glucose and synthesis of glycogen.
Function: secrete glucagon. It stimulates: release of glucose into the bloodstream, gluconeogenesis and glycogenolysis in the liver, proteolysis, lipolysis.
Function: secrete somatostatin. It is identical to hypothalamic hormone that regulate somatotropin release from anterior pituitary gland. It inhibits both insulin and glucagon secretion.
PP (F) cells secrete Pancreatic polypeptide, that stimulates gastric chief cells, inhibits bile and pancreatic secretion, and intestinal motility.
D-1 cells secrete Vasoactive intestinal peptide (VIP) that actions are similar to those of glucagon, and stimulates pancreatic exocrine secretion.
EC cells (enterochromaffin cells) secrete secretin (stimulates bicarbonate and pancreatic enzyme secretion), motilin (increases gastric and intestinal motility) and substance P (?).