27.29 : Pancreas

The pancreas, an essential organ in the human body, is a pinkish-gray elongated structure located posterior to the stomach. It extends laterally from the duodenum towards the spleen and is firmly bound to the posterior wall of the abdominal cavity. The organ's surface has a lumpy, lobular texture that gives it a unique appearance.

The broad head of the pancreas lies within the loop formed by the duodenum, while its slender body reaches towards the spleen. The tail of the pancreas is short and bluntly rounded. This organ plays a dual role, serving both exocrine and endocrine functions.

The exocrine part of the pancreas produces pancreatic juice, which aids in digestion. This section consists of acini and ducts. Acini are clusters of secretory acinar cells that produce an enzyme-rich component of pancreatic juice. These cells are filled with rough endoplasmic reticulum and zymogen granules, the latter containing inactive digestive enzymes. The ducts transport these secretions from the acinar cells. The large pancreatic duct delivers the secretions to the duodenum. In some individuals, an accessory pancreatic duct branches from the main pancreatic duct.

The pancreatic duct meets the common bile duct in the duodenum. Both these ducts empty into the duodenal ampulla, a chamber roughly halfway along the length of the duodenum. The passage of pancreatic juice and bile is regulated by the sphincter of the hepatopancreatic ampulla, also known as the sphincter of Oddi.

The endocrine part of the pancreas consists of scattered mini-endocrine glands called pancreatic islets. These islets secrete crucial hormones like insulin and glucagon, which regulate the body's glucose levels.