The Pancreas and Liver
One of the endocrine glands, the pancreas, actually pulls double duty as a digestive organ. Sitting behind the stomach, the spongy pancreas secretes both digestive enzymes and endocrine hormones. It is long and tapered with a thicker bottom end (or head), which is cradled in the downward curve of the duodenum — the first portion of the small intestine or bowel. The long end (or tail) of the pancreas extends up behind the stomach toward the spleen. A main duct, or channel, connects the pancreas to the duodenum.
In the pancreas, specialized cells known as exocrine tissue secrete digestive enzymes into a network of ducts that join the main pancreatic duct and end up in the duodenum, where they are key in processing carbohydrates, proteins, and other nutrients.
The endocrine tissues of the pancreas contain cell clusters known as islets of Langerhans, named after Dr. Paul Langerhans, who first described them in medical literature. Islets (pronounced EYE-lets) are constructed of three cell types:
Alpha cells manufacture and release glucagon (pronounced glue-co-gone), a hormone that raises blood glucose levels.
Beta cells monitor blood sugar levels and produce glucose-lowering insulin in response.
Delta cells produce the hormone somatostatin, which researchers believe is responsible for directing the action of both the beta and alpha cells.
People with type 1 diabetes should have an emergency glucagon injection kit on hand. Glucagon is a hormone that prompts the liver to release glycogen and convert it into glucose. It is used to treat a severe hypoglycemic episode, or low blood sugar, in someone who has lost consciousness.
Another Key Player: The Liver
Located toward the front of the abdomen near the stomach, the liver is the center of glucose storage. This important organ converts glucose — the fuel that the cells of the human body require for energy — into a substance called glycogen. Glycogen is warehoused in muscle and in the liver itself, where it can later be converted back to glucose for energy with the help of the hormones epinephrine (secreted by the adrenal glands) and glucagon from the pancreas.
Together, the liver and pancreas preserve a delicate balance of blood glucose and insulin, produced in sufficient amounts to both fuel cells and maintain glycogen storage.