The pancreas has two functions:
a. Exocrine gland – Glands that discharge hormones into ducts
b. Endocrine gland – Glands that secret hormones into the bloodstream
The pancreatic endocrine function is to release the hormones insulin and glucagon into the bloodstream to regulate glucose levels.
The pancreatic exocrine function releases digestive enzymes into the duodenum (first, connected to the stomach, and smallest part of the small intestine).
The pancreas is located benefit the stomach and the pancreatic head is wrapped around by the duodenum.
Bile, an alkaline fluid that helps digest lipids, is transmitted from the gall bladder to the pancreas through the common bile duct connecting to the pancreas at the pancreatic duct or duct of Wirsung. The pancreatic duct collections this alkaline fluid and digestive juices: trypsin, chymotrypsin, pancreatic lipase, and pancreatic amylase, and empties into the duodenum just prior to the ampulla of Vater. The ampulla of Vater regulates the flow of bile and pancreatic juices into the duodenum.
A smaller duct (duct of Santorini) also empties into the duodenum. Enzymes active in the digestion of carbohydrates, fat, and protein flow through these ducts continuously and at an increased rate when food is present in the small intestine. About 41 fluid ounces of digestive juices are secreted daily. Flow is controlled by the vagus nerve and by the hormones secretin and pancreozymin, produced in the intestinal mucosa.
When food enters the duodenum, secretin and pancreozymin (cholecystokinin / pancreozymin hormone) are released in the bloodstream by the duodenum secretary cells. When these hormones reach the pancreas, the pancreas cells are stimulated to produce and release large amounts of digestive enzymes, which then flow into the intestine. When the enzymes reach the intestine, the duodenum stops producing secretin and pancreozymin hormones.
The pancreas cells that produce digestive enzymes are called acinar cells (Latin acinus – grape), so named because the cells aggregate to form bundles appear much like a cluster of grapes. The base of the cell has fine tubules (endoplasmic reticulum) that produce the secretary granules. These granules are transported from the tubules to a more complex tubular apparatus (Golgi) that concentrate the secretions. The Golgi encases the enzymes in a thin membrane and sends them to the top of the cell. The enzyme granules pass through the acinar cell wall into a complicated network of ducts that eventually reaches the small intestine.
Located between the clusters of the acinar cell area are scatched patches of another type of secretary tissue called the islands (islets) of Langerhans, named after the 17th century German pathologist Paul Langerhans. The islets are responsible for the secretion of insulin and glucagon, which control the amount of sugar stored in the body. Unlike the acinar tissue, the islets of Langerhans secret their substances directly into the blood stream.
Insulin is vital in carbohydrates (sugar) metabolism. Insulin causes the body to store glucose as glycogen. Insulin stimulates the body's cells to remove glucose sugar from the blood stream and utilize it. Diabetes mellitus is caused when there is a shortage of insulin in the bloodstream. Sugar then remains in the blood and glucose is not converted into glycogen stores for the body. Too much insulin reduces the amount of sugar in the blood.
Glucagon has the opposite effects of insulin. Glucagon is also a hormone used for carbohydrate metabolism. Glucagon is released into the bloodstream when the glucose levels are low (hypoglycemia) causing the liver to convert glycogen to glucose in the bloodstream Glucagon releases stored sugar and increase the blood sugar level. Glucagon acts as a control mechanism when the body produces too much insulin.