Pancreas - Islets of Langerhans

Insulin, the hormone that lowers the amount of glucose (sugar) in the blood is produced in the Beta cells that are located in the Islets of Langerhans. The Islets of Langerhans are where the endocrine (hormone-releasing) cells in the pancreas are located. The Islets are patchy and irregular shaped in the human pancreas. The Islets contain alpha, beta, delta, gamma, epsilon, and F-cells that surround the enzyme-secreting acinar cells. The Islets are evenly distributed around the pancreas and normal human pancreas contains about one million of these Islets.

Alpha cells in the Islets of Langerhans produce the hormone glucagon. Glucagon is released when glucose levels in the blood are low and glucagon stimulates the liver to convert glycogen to glucose.

Beta cells produce the hormones insulin and amylin. Beta cells make up about 70 percent of the Islets. Insulin is manufactured, stored, and secreted by the beta cells. Glucose moves from the blood into the body’s cells by the hormone insulin. Insulin assists in the metabolism of the glucose. Amylin is very similar to insulin in that it helps to reduce glucose in the blood. Amylin decreases the secretion of glucagon and moderates the emptying of the stomach,

Delta cells in the Islets produce the hormone somatostatin. The endocrine system is regulated by the peptide hormone somatostatin. Pancreatic somatostatin inhibits the release of glucagon and insulin.

Epsilon cells (ε-cells) produce the hormone ghrelin. Ghrelin stimulates appetite. Ghrelin hormones are increased before meals and are decreased after meals. The ghrelin hormone signals the hypothalamus in the brain. Body temperature, hunger, thirst, fatigue, anger, and sleep are controlled by the hypothalamus.

F Cells (PP cells) are pancreatic polypeptide producing cells. The PP cells are mainly found in the Islets of Langerhans at the head of the pancreas. The pancreatic polypeptide hormone is expressed at times when glucose levels in the blood are low. This can be created from fasting, exercising, eating protein meals, or from being hypoglycemic (low blood sugar). The increase of somatostatin and glucose in the blood decrease the PP levels. Having too little PP hormones appears to stimulate appetite, lessens the ability to resist the temptation of food, and increases the chances of a person becoming overweight.