Pancreas, exocrine

The pancreas is a vital organ in the digestive system and the endocrine system of vertebrates. It is both an endocrine gland—producing several important hormones, including insulin, glucagon, and somatostatin—and a digestive organ, secreting pancreatic juice containing digestive enzymes that assist in the absorption of nutrients and digestion in the small intestine.

Anatomy

The pancreas is located in the abdomen and is approximately 15 cm long. It is situated behind the stomach and is connected to the duodenum via the pancreatic duct. The pancreas is divided into four parts: the head, neck, body, and tail.

Head

The head of the pancreas is nestled in the curve of the duodenum. It is the broadest part of the pancreas and is connected to the duodenum by the ampulla of Vater.

Neck

The neck of the pancreas is the constricted part of the organ that lies between the head and the body. It is located anterior to the superior mesenteric vessels.

Body

The body of the pancreas extends from the neck to the tail and lies behind the stomach.

Tail

The tail of the pancreas is the narrowest part and extends to the hilum of the spleen.

Exocrine Function

The exocrine function of the pancreas involves the secretion of digestive enzymes into the duodenum. These enzymes are crucial for the digestion of carbohydrates, proteins, and lipids.

Acinar Cells

The exocrine pancreas is composed of clusters of cells known as acinar cells. These cells produce zymogens, which are inactive enzyme precursors. The zymogens are secreted into the pancreatic duct and activated in the duodenum.

Pancreatic Duct

The pancreatic duct is a major duct that runs the length of the pancreas and drains the pancreatic juice into the duodenum. The duct of Wirsung is the main pancreatic duct, and it joins the common bile duct to form the ampulla of Vater.

Digestive Enzymes

The pancreas secretes several key digestive enzymes:

• Amylase: Breaks down starch into sugars.
• Lipase: Breaks down fats into fatty acids and glycerol.
• Proteases: Such as trypsin and chymotrypsin, which break down proteins into peptides and amino acids.

Regulation of Secretion

The secretion of pancreatic juice is regulated by both hormonal and neural mechanisms. The hormone secretin stimulates the pancreas to secrete a bicarbonate-rich fluid, while cholecystokinin (CCK) stimulates the secretion of enzyme-rich pancreatic juice. The vagus nerve also plays a role in stimulating pancreatic secretion.

Clinical Significance

The exocrine function of the pancreas can be affected by various diseases, including:

Pancreatitis

Pancreatitis is the inflammation of the pancreas, which can be acute or chronic. It is often caused by gallstones or alcohol abuse.

Pancreatic Insufficiency

Pancreatic insufficiency occurs when the pancreas does not produce enough digestive enzymes, leading to malabsorption and nutritional deficiencies.

Cystic Fibrosis

Cystic fibrosis is a genetic disorder that affects the exocrine glands, including the pancreas, leading to thick secretions that block the pancreatic ducts.

See Also

• Endocrine pancreas
• Insulin
• Glucagon
• Somatostatin