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How does the pancreas work?

Last Update: December 30, 2016; Next update: 2019.

The pancreas is 12 to 18 centimeters (about 4.7 to 7.1 inches) long and weighs about 70 to 100 grams. The pancreas is made up of a head, a body and a pointy tail. It is located in the upper abdomen behind the stomach. The organ has two major functions. It produces

Illustration: Position of the pancreas - as described in the information

Position of the pancreas

Hormones and enzymes are produced in two different groups of cells:

Exocrine pancreas cells

Over 99% of the exocrine pancreas cells produce digestive juices – about 1.5 to 2 liters per day. They are called exocrine ("secreting externally") because they secrete digestive juice "externally" into the small intestine. This clear, colorless juice is mainly made up of water and also contains salt, sodium bicarbonate and digestive enzymes. There are enzymes for breaking down fats (lipases), proteins (proteases), and carbohydrates (amylases). Proteases are inactive while inside the pancreas. They are activated once they have been secreted into the small intestine. The sodium bicarbonate neutralizes the acidic gastric (stomach) juice in the mass of semi-digested food to help the digestive enzymes work better.

The digestive juices flows from the pancreas through an excretory duct into the small intestine. In most people, this duct joins up with the the excretory duct of the gallbladder before reaching the small intestine. A sphincter muscle at the end of the duct controls the flow of digestive juice into the small intestine.

In case of pancreatitis, enzymes may be activated inside the pancreas before reaching the small intestine, causing the gland to start "digesting itself."

Illustration: Pancreas and neighboring organs - as described in the information

Pancreas and neighboring organs

Endocrine pancreas cells

Groups of endocrine cells are spread over the surface of the pancreas. They are called islets of Langerhans, because they are scattered like small islands and were discovered by pathologist Paul Langerhans. These islet cells produce insulin, glucagon and other hormones. They are called endocrine ("secreting internally") cells, because they secrete hormones directly into the blood. These hormones help to regulate blood sugar levels and keep them from getting too high or too low.

When the blood sugar levels rise, as they might after a meal, insulin is released by the islets of Langerhans. The insulin is then able to transport sugar from the blood into the cells of the body, where it can be converted into energy. Insulin also allows the liver and the muscles to store more sugar, as well as keeping the liver from producing more sugar. This has the effect of lowering blood sugar levels.

When blood sugar levels are too low, the pancreas releases glucagon into the bloodstream. This hormone acts as an antagonist to insulin. It causes the liver cells of the liver to release stored sugar and to convert proteins into sugar to make them available as a source of energy too. The flow of glucagon is stopped once blood sugar levels rise.


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    Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.

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