The Pancreas An Integrated Textbook of Basic Science, Medicine, and Surgery Ebook PDF
The Pancreas An Integrated Textbook of Basic Science, Medicine, and Surgery Ebook PDF The pancreas is a unique exocrine and endocrine organ disparate cell types come together to form the pancreas. located in the retroperitoneal region of the upper abdominal cavity.
In humans, when fully formed, the organ has a distinct head, body, and tail, with the head of the pancreas contacting the duodenal region of the intestines (the main pancreatic duct drains into the duodenum) and the tail of the pancreas abutting the spleen. The greatest mass of the organ is present in the head, which is composed of tissue derived from two independent anlagen (see later). In other mammals, such as dogs and mice, the organ has a far less distinct structure and is identified as an amorphous pink tissue adjacent to the mesentery that runs along the upper intestinal wall.
The cells of the pancreas are arranged into distinct lobules composed primarily of the digestive enzyme‐producing cells of the exocrine pancreas, which are arranged into acini (so‐called acinar cells), the ductal structures that conduct these digestive enzymes to the intestines, and distinct clusters of endocrine cells, the islets of Langerhans, that secrete hormones and function to regulate glucose uptake and release and serum glucose levels. There are five recognized cell types within the islets, the α, β, δ, ε, and PP cells, which produce the hormones glucagon, insulin, somatostatin, ghrelin, and pancreatic polypeptide, respectively.
The majority of the pancreatic tissue mass (more than 90–95%) is present within the exocrine compartment of the organ, with the islets of Langerhans, scattered throughout the tissue. The pancreas also has connective tissue, derived from the embryonic mesenchyme, which forms the septa that separate the many lobules of the organ.