Pancreas

By Regina Bailey

Biology Expert

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Pancreas

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Pancreas. Photo Credit: Image Credit: Don Bliss / National Cancer Institute

Updated June 23, 2016.

Pancreas

The pancreas is a soft, elongated organ located in the upper abdominal area of the body. It is a component of both the endocrine system and the digestive system. The pancreas is a gland that has both exocrine and endocrine functions. The exocrine portion of the pancreas secretes digestive enzymes, while the endocrine segment of the pancreas produces hormones.

Pancreas Location and Anatomy

The pancreas is elongated in shape and extends horizontally across the upper abdomen.

It consists of a head, body, and tail region. The wider head region is located in the right side of the abdomen, nestled in the arc of the upper portion of the small intestine known as the duodenum. The more slender body region of the pancreas extends behind the stomach. From the body of the pancreas, the organ extends to the tapered tail region located in the left side of the abdomen near the spleen.

The pancreas is comprised of glandular tissue and a duct system that runs throughout the organ. The vast majority of glandular tissue is composed of exocrine cells called acinar cells. The acinar cells are assembled together to form clusters called acini. Acini produce digestive enzymes and secrete them into nearby ducts. The ducts collect the enzyme containing pancreatic fluid and drain it into the main pancreatic duct. The pancreatic duct runs through the center of the pancreas and merges with the bile duct before emptying into the duodenum. Only a very small percentage of pancreatic cells are endocrine cells.

These small clusters of cells are called islets of Langerhans and they produce and secrete hormones. The islets are surrounded by blood vessels, which quickly transport the hormones into the bloodstream.

Pancreas Function

The pancreas has two main functions. The exocrine cells produce digestive enzymes to assist in digestion and the endocrine cells produce hormones to control metabolism. Pancreatic enzymes produced by acinar cells help to digest proteins, carbohydrates and fats. Some of these digestive enzymes include:

Pancreatic proteases (trypsin and chymotrypsin) - digest proteins into smaller amino acid subunits.
Pancreatic amylase - aids in the digestion of carbohydrates.
Pancreatic lipase - aids in fat digestion.

The endocrine cells of the pancreas produce hormones that control certain metabolic functions, including blood sugar regulation and digestion. Some of the hormones produced by the islets of Langerhans cells include:

Insulin - lowers glucose concentrations in the blood.
Glucagon - raises glucose concentrations in the blood.
Gastrin – stimulates gastric acid secretion to aid digestion in the stomach.

Pancreas Hormone and Enzyme Regulation

The production and release of pancreatic hormones and enzymes are regulated by the peripheral nervous system and gastrointestinal system hormones. Neurons of the peripheral nervous system either stimulate or inhibit the release of hormones and digestive enzymes based on environmental conditions. For instance, when food is present in the stomach, peripheral system nerves send signals to the pancreas to increase the secretion of digestive enzymes. These nerves also stimulate the pancreas to release insulin so that cells can take up the glucose obtained from the digested food. The gastrointestinal system also secretes hormones that regulate the pancreas to aid in the digestive process. The hormone cholecystokinin (CCK) helps to elevate the concentration of digestive enzymes in pancreatic fluid, while secretin regulates the pH levels of partially digested food in the duodenum by causing the pancreas to secrete a digestive juice that is rich in bicarbonate.

_Sources:

_{SEER Training Modules, Introduction to the Endocrine System. U. S. National Institutes of Health, National Cancer Institute. Accessed 10/21/2013 (http://training.seer.cancer.gov/anatomy/endocrine/)}
_{What You Need To Know About Cancer of the Pancreas. National Cancer Institute. Updated 07/14/2010 (http://www.cancer.gov/cancertopics/wyntk/pancreas)}