Pancreas

The pancreas is a long, soft organ that sits behind the stomach in the upper belly. In an adult, it is about six inches long and shaped a bit like a flat fish. The pancreas is part of two body systems at once. It helps the digestive system break down food, and it helps the endocrine system control sugar in the blood. Few organs do two such different jobs.

The first job is digestion. After you eat, food leaves your stomach and enters your small intestine. The pancreas sends a special juice into the small intestine through a thin tube called the pancreatic duct. This juice contains chemicals called enzymes. Enzymes act like tiny scissors. They cut food into pieces small enough for your body to use. Different enzymes cut different things. Some chop up proteins from meat or beans. Others break down fats from butter or oil. Others split starches from bread or potatoes.

The second job is controlling blood sugar. Deep inside the pancreas are tiny clusters of cells called the islets of Langerhans. These cells make two important hormones, insulin and glucagon. A hormone is a chemical messenger that travels through the blood. When you eat a sandwich, your blood sugar goes up. The pancreas releases insulin, which tells your body's cells to pull sugar out of the blood and use it for energy. When you have not eaten in a while and your blood sugar drops, the pancreas releases glucagon instead. Glucagon tells the liver to send stored sugar back into the blood.

If the pancreas stops making enough insulin, a person can develop diabetes. In type 1 diabetes, the body's own immune system attacks the insulin-making cells by mistake. In type 2 diabetes, the cells stop responding to insulin the way they should. People with diabetes have to keep careful track of their blood sugar. Many of them take insulin as medicine. Before insulin was discovered in 1921, type 1 diabetes was almost always deadly. Today, millions of people live long lives with it.

Doctors are still working on better treatments. Some scientists are trying to grow new insulin-making cells in the lab and put them into patients. Others are testing tiny machines that act like a robot pancreas, measuring blood sugar and giving insulin all on their own. Your pancreas may be hidden behind your stomach, but it works hard every time you eat.