Expert: John Locke - 4/22/2007

Question
1. what is insulin?
2. what is the use of a pancreas?

Answer
Thank you for using AllExperts, and I'd be happy to answer your question.

The body has two general ways of regulating the activities of its organs and body systems: the nervous system and the endocrine system. The nervous system, of course, controls body systems by nerve impulses (when I say "control the body," I mean that the nervous and endocrine systems speed up or slow down the organs that they target); these signals (which are basically electrical impulses) travel along the nerve fibers. The endocrine system works by hormones that travel through the blood; these are basically chemical signals that attach to their target cells and tell those targets to do something specific. Insulin is a hormone, and part of the endocrine system.

Insulin itself is a protein hormone made by the pancreas. When released into the bloodstream, it travels to muscle cells and tells them to absorb glucose from the bloodstream. It also signals them to make glycogen with that glucose, which is a complex structure made of many glucose molecules strung together. The body stores glucose in the form of glycogen when it is not using it directly. Thus, insulin regulates the amount of glucose present in the blood, more commonly referred to as blood sugar. Because more sugar is going to be present in the blood after a meal, insulin release takes place in the highest amounts after eating.

The function of the pancreas is tied directly to the regulation of blood glucose levels, as the pancreas makes the hormones that control it. Both insulin and glucagon (which is a hormone that has exactly the opposite functions of glucose--it causes the breakdown of glycogen into glucose) are manufactured by cells in the pancreas, and indeed not having a properly functioning pancreas causes the disease diabetes. The blood glucose regulation side of the pancreas is known as its endocrine function.

In addition, the pancreas also manufactures enzymes that break down different parts of food. The human body must first break down the food it eats into its simplest, most basic components before they can be absorbed into the bloodstream. The pancreas, liver, and small intestine all secrete chemicals that promote this process, starting in the small intestine, with the pancreas working specifically on proteins and fats. This is known as the exocrine function of the pancreas.

As you might have guessed, the pancreas is an essential organ; its functions are basic to human life, and life without a functional pancreas is extremely difficult. To put it in perspective, pancreatic cancer (which in most cases results in the failure of the pancreas) has the highest mortality rate of all cancers known. Such is not the case even with cancers in other essential organs, like the lungs or liver.