The pancreas is an elongated, flattened glandular organ with two vital responsibilities. It produces enzymes necessary to digest carbohydrates, fats and proteins, and it produces insulin, a hormone that is essential in the regulation of glucose (blood sugar), the body's main source of energy.

This oblong gland, which measures about 5 to 6 inches (13 to 15 centimeters) long, is located between the stomach and the spine. It is composed of glandular tissue and a system of ducts, which are tubes that carry the fluids secreted by glands. The main duct is known as the pancreatic duct. It transports fluid and enzymes from the gland to the duodenum, the upper part of the small intestine.

The pancreas is usually described either by the function of its cells or by its parts. It has two functional components:

• Endocrine cells (also known as the islets of Langerhans, islet cells or beta-islet cells). “Endo” means within. There are about 100,000 endocrine cells scattered throughout the pancreas. The pancreatic hormones produced in the islets of Langerhans are composed of various types of cells, including alpha, beta and delta cells. These are responsible for producing and secreting hormones into the bloodstream, including insulin (produced by beta cells), which lowers glucose levels, and glucagon (produced by alpha cells), which raises glucose levels. These hormones maintain proper glucose levels within the bloodstream and help the body use that sugar for energy within the cells. Delta cells in endocrine tissue secrete somatostatin, a hormone that inhibits the release of insulin and glucagon. The pancreas also produces gastrin, a hormone that stimulates the stomach to produce digestive acid.
  
  
• Exocrine cells (also known as acinar cells or non-endocrine cells). “Exo” means outward. These cells make up the majority of the pancreas. They produce and transport proteins (known as enzymes) and fluids that assist in digestion of carbohydrates, fats, proteins and acids in the duodenum. The enzymes are secreted into ducts joined to the main pancreatic duct that is found along the length of the pancreas. The enzymes then travel down into the area where the pancreatic duct enters the duodenum together with the bile duct within a bulbous structure known as the ampulla of Vater. Finally, the enzymes enter the duodenum and become activated. Exocrine tissue also secretes bicarbonate that neutralizes stomach acid and inhibits the formation of ulcers.

The pancreas can also be categorized by its five sections:

• Head. The gland’s widest part, it is on the right side of the abdomen and lies in the curve of the duodenum.
  
  
• Neck. A thin section located between the gland’s head and body.
  
  
• Body. The middle part of the pancreas, it is found between the neck and tail. The body is located in front of the superior mesenteric blood arteries and veins, which supply the intestines with blood.
  
  
• Tail. The thin tip, it is found on the left side of the abdomen near the spleen.
  
  
• Uncinate process. This part bends backward and is found underneath the pancreas’ head. The superior mesenteric arteries and veins cross in front of this part.

When food is digested, it is transported through the esophagus and into the stomach. There, digestive juices break down (digest) food. The food then flows into the duodenum where digestion continues.

At this point, bile, a greenish-yellow liquid produced in the liver that assists in digesting fats and pancreatic fluids is secreted into the small intestine. These liquids, along with the food, continue through the small intestine, where glucose travels into the bloodstream, and then through the large intestine and rectum.