The pancreas is both an endocrine and exocrine organ.  The endocrine portion of the pancreas makes the hormones insulin and glucagon that are distributed throughout the body by way of the bloodstream.  The exocrine pancreas creates digestive enzymes and bicarbonate, a chemical that neutralizes stomach acid.  The cells that provide endocrine and exocrine functions are different from each other but are evenly dispersed throughout the pancreas.  Without pancreatic bicarbonate, stomach acid would harm the small intestines.  The pancreas creates enzymes that help break down the components of food.  Trypsin, chymotrypsin, and peptidases break down proteins.  Amylase breaks down carbohydrates.  Lipase breaks down fats.  Nucleases break down RNA and DNA.

What is the endocrine function of the pancreas?

The endocrine pancreatic tissue makes insulin and glucagon.  These two hormones help regulate the use of sugar by the body.  Insulin and glucagon help keep the level of blood sugar relatively constant whether a person is eating or between meals.  Insulin is secreted in response to a meal, instructing the body cells to increase adsorption of sugar and to store the extra sugar as glycogen.   Glucagon is secreted when the body is fasting (i.e., between meals).  Higher glucagon levels instruct the body to release sugar from glycogen (which is a sugar storage molecule), and to create sugar from other sources.

What happens when the endocrine pancreas does not work?

Childhood diabetes (type I diabetes) occurs when the body loses function of the endocrine pancreas.  Decreased production of insulin causes the blood sugar level to rise.  Because insulin is not available to help the body's cells adsorb sugar, the cells of the body begin "starving," despite the large amount of sugar in the bloodstream.

What is the exocrine function of the pancreas?

The exocrine pancreatic tissue helps the body digest food.  Enzymes are created in response to eating and released into the small intestines.  The major enzymes are:

• Trypsin, chymotrypsin, peptidases - break down proteins
• Amylase - breaks down carbohydrates
• Lipase - breaks down fats
• Nucleases - break down DNA and RNA

Why does the pancreas make bicarbonate?

Bicarbonate is a chemical that helps neutralize stomach acid.  As stomach acid empties into the small intestines, bicorbonate is released from the pancreas.  The small intestines do not have a mucous layer like the stomach to protect against acid.  Without bicarbonate, the small intestines would become injured by stomach acid, causing inflammation and ulcers.

Photo - The pancreas.  Gray's Anatomy.