Question

What are the functions of the pancreatic hormones?

Answer 1

Pancreatic hormones are the set of hormones; majorly glucagon, insulin, somatostatin, pancreatic polypeptide hormone; secreted by a specialized tissue within the pancreas, called Islets of Langerhans. Pancreatic hormones help in maintaining constant blood glucose levels, storage of carbohydrates and fats into glycogen after meals and the mobilization of energy by the breakdown of glycogen reserves upon body needs.

The islets of Langerhans contain four types of cells secreting four different hormones;

• Alpha cells/ A cells (approximately 25% of islet cells) produces glucagon. Glucagon acts in the liver and is stimulated by low blood glucose level. Glucagon increases blood glucose level by stimulating;
  

1. Glycogenolysis; the breakdown of glycogen to glucose.
2. Gluconeogenesis; the production of glucose from non-sugar molecules such as amino acids and glycerol.
3. Lipolysis; the breakdown of triacylglycerols into glycerol and fatty acids.

• Beta cells/ B cells (~60% of islet cells) produces insulin. Insulin-stimulated by higher blood glucose level lowers the blood glucose level by;

1. acts on the liver to promote glucose storage.
2. promotes glycolysis (anaerobic conversion of glucose to lactate) and glycogenesis (production of glycogen from glucose).
3. Promotes glucose uptake by skeletal muscles by increasing the amount of GLUT-4 glucose transporters.
4. Inhibits glycogenolysis and gluconeogenesis.
5. Increased uptake of amino acids and conversion of it into proteins.

• Delta cells/ D cells (~10% of islet cells) produces somatostatin. Somatostatin stimulated by higher plasma concentration of glucose and arginine. Somatostatin has multiple functions, altogether reducing the nutrient absorption rate from food in the intestine. Somatostatin;

1. inhibits gastrin and hydrochloric acid secretion in the stomach.
   
2. inhibits release of secretin and cholecystokinin from the duodenum.
3. inhibits glucagon secretion from the pancreas.

• F cells/ PP cells (~5% of islet cells) produces the pancreatic polypeptide, which reduces appetite.