Pancreas

The pancreas is a gland located within the abdomen, found in both vertebrate animals and humans. It sits behind the lower part of the stomach, near the beginning of the small intestine (duodenum). The pancreas has two major functions: the production of enzyme-rich digestive juices that break down food, and the production of hormones that circulate in the blood and regulate blood sugar levels.

Because the pancreas combines two functions, it is described as both an "exocrine" and "endocrine" organ. The exocrine portion releases enzymes through small ducts that join together into a larger duct emptying into the small intestine. The endocrine portion, which produces hormones, releases them directly into the blood.

Structure

The pancreas is typically divided into four parts: the head, neck, body, and tail. The head is the widest section, lying against the small intestine; the tail extends toward the heart on the left side and lies close to the left kidney (spleen). The most numerous cell type in the pancreas is the acinar cells, which produce enzymes, while hormone-producing cells are clustered in small groups called the islands of Langerhans.

Digestive function

Pancreatic digestive juices contain enzymes that break down food: those that break down protein (such as trypsin and chymotrypsin), those that break down fat (lipase), and those that convert starch into sugar (amylase). The juices also contain bicarbonate, which neutralizes acid coming from the stomach, allowing the enzymes to work at the proper pH level. Most enzymes are released in an inactive form and are activated in the small intestine—a mechanism that prevents the pancreas from digesting itself.

Hormones

The most common hormones are insulin and glucagon. Insulin, produced by beta cells, lowers blood sugar levels when they rise, enabling cells to take up glucose. Glucagon, produced by alpha cells, works oppositely: when blood sugar falls, it stimulates the liver to release glucose. The pancreas also produces somatostatin and other hormones that affect digestion and nutrient processing.

Associated diseases

When insulin production is insufficient or the body cannot use it effectively, diabetes mellitus results. Pancreatic inflammation (pancreatitis) can be acute or chronic; causes include gallstones and alcohol use. Pancreatic cancer is often diagnosed late because early symptoms are not distinctive.