What is the pancreas?

The backyard neighbor to the liver, the pancreas primarily gets attention for its role in producing insulin. But that's not all it does.

Looking like a strip steak with a fish head, the pancreas is about six inches long. Attached to the muscles and tissues near your back (which is one of the reasons why it causes back pain when diseased), the pancreas has two very different roles with specialized exocrine and endocrine parts to carry out these tasks. (Exocrine implies it secretes and has actions locally; endocrine means it most commonly secretes into the bloodstream.)

The exocrine role is performed by acini—they're grapelike bundles of cells that secrete pancreatic juice. When food hits the first part of your small intestine, these cells squeeze out juices to digest food so it can be absorbed in the small intestines.

The pancreatic juices also neutralize the strong acids from the stomach so they don't damage the intestines downstream. (About 1,500 ml or six cups) of pancreatic juice is secreted every day. It contains water, ions, and a variety of proteins.)

Pancreatitis is often caused by a blockage of the pancreatic duct, which forces these powerful chemicals to spill over and literally digest the pancreas itself.

Pancreatic enzymes play very specific roles in how protein, fat, and carbohydrates and broken down chemically so they can be used elsewhere in the body. The good news is that although the levels of digestive juice decline as you age, you usually die with your pancreas having considerable kick to do its digestive job, so you really never have to supplement with digestive enzymes unless you get a pancreatic disease or are born without them.

Now, it's likely the endocrine part of the pancreas that you're more familiar with. This contains tissue that sounds like it belongs more on a map than in an organ—the islets of Langerhans.

These islet cells constitute less than 2 percent of the mass of the pancreas but manufacture hormones like insulin. Hormones produced in the Islets of Langerhans are secreted directly into the blood flow by (at least) four different types of cells, and you can think of them like members of a Greek fraternity, minus the pledge paddles and hazing incidents.