These are the cells that produce insulin, the hormone that helps the body store and use glucose. Think of insulin as the U.S. Postal Service and glucose as the mail; insulin is responsible for delivering that glucose (sugar) from the bloodstream into muscle, fat, liver and most other cells so that your body can use it for fuel. We wish insulin had a similar mantra as the USPS—neither blood, nor fat, nor DNA will keep insulin from delivering glucose throughout the body—but it doesn't quite work that way. Problems happen when either the pancreas doesn't make enough insulin or various parts of the body block insulin and prevent it from delivering glucose to those cells.
Alpha cells release a substance called glucagon, which forces your body to make more glucose when you're exercising (and helps break down fat in this process). And you thought that huffing, sweating and getting hit on were the only things that happened during exercise.
The Other Cells
Three other types of cells round out the team. Delta cells are part of the feedback loop in the pancreas; remember that almost all biologic processes have a built-in "off switch" like this. These cells produce somatostatin, which, among other actions, turns off the alpha and beta cells. PP cells may sound like code for preschool bathrooms, but these cells contain pancreatic polypeptide and prevent pancreatic enzymes from being secreted into the gut after a protein meal, fasting and exercise. Finally, a few epsilon cells contain the hormone ghrelin, which stimulates our hunger and very often causes us to eat like a bear in a stream of salmon.