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How does the pancreas work?

The pancreas is 12 to 18 centimeters (about 4.7 to 7.1 inches) long and weighs about 70 to 80 grams. This gland is located across the upper abdomen behind the stomach. It plays an important role in digestion and in regulating blood sugar levels. To do this it produces

enzymes, which break down foods in the intestine, as well as
hormones such as insulin, which maintain a constant blood sugar level.

The pancreas is made up of a head, a body and a pointy tail. Inside of the pancreas there are many small glandular cells. Over 99% of these glandular cells produce digestive juices – about 1.5 to 2 liters per day. This clear, colorless “pancreatic juice” is then released into the intestine. It is mainly made up of water and also has salt, sodium bicarbonate and digestive enzymes in it. Sodium bicarbonate neutralizes the acidic gastric (stomach) juice in the mass of semi-digested food, ensuring that the digestive enzymes can work optimally. Pancreatic juice also helps to break down protein, sugar, and fats.

Between the glandular cells that produce digestive juice, there are tiny collections of different glandular cells like islands (also called islets of Langerhans). These islet cells produce insulin, glucagon and other hormones and release them into the bloodstream. The hormones make sure that the blood sugar level is neither too high nor too low.

When the blood sugar level rises, for instance following a meal, the pancreas releases insulin. Insulin enters the bloodstream and ensures that the sugar in the food and drinks we consume is transported from our blood to our cells, where it is transformed into energy for the body. Insulin also causes the liver and the muscles to store sugar, and inhibits new production of sugar in the liver. This is how the blood sugar level falls.

When blood sugar levels are low, the pancreas releases glucagon into the bloodstream. This hormone causes the cells of the liver to release stored sugar. Glucagon also ensures that the cells of the liver produce new sugar from other substances in the body. When the blood sugar level has risen, the release of glucagon is stopped once again.

Author: Institute for Quality and Efficiency in Health Care (IQWiG)