Question

Describe the exocrine and endocrine functions of the pancreas?

Which type of the cells in the pancreas secrets insulin?

The pancreas is allowed to regenerate fully after 70% pancreatectomy, what type of cells are the regenerated insulin-producing cells derived from? What study did people do to demonstrate this.

Answer 1

• Pancreas is elongated in shape and lies behind stomach above first loop of duodenum.
• Pancreas acts as both endocrine as well as exocrine gland.
• Endocrine portion of pancreas is formed by islets of Langerhans secrete insulin and glucagon into blood stream.
• Endocrine portion consists of three types of cells which function in response to glucose levels in the blood.
• α cells : secrete glucagon
• β cells : secrete insulin
• ∆ cells. : Secrete somatostatin
• Exocrine function of pancreas include secretion of pancreatic juice, this secretion is considered exocrine as it is not directly secreted into blood but into ducts which join to form the pancreatic duct.
• Exocrine part is formed by acinar cells (which secrete pancreatic enzymes for eg. Lipase, amylase, nuclease and proteolytic enzymes) and duct cells( secrete alkaline solution).
• Pancreatectomy is surgical removal of complete (mostly due to presence of cancerous lesions) or a part of pancreas(field defects).
• Pancreas possess limited potential to regenerate itself, it has been reported that either regenerate from pre existing β cells in proximity of network of pancreatic duct or from other types of pancreatic endocrine cells.
• For demonstration of regenerative potential of pancreas the most commonly used model is the injury model, in which 90% and 90-95% of portion of pancreas is removed in adult rats and snails respectively, after which the remaining part is allowed to regenerate, the results of which elucidate that pancreatectomy results in upregulation of expression of Pdx 1 by IGF/PI3K pathway which result in limited recovery of the organ mostly proportional to the size of excised portion, first by rapid proliferation of ductal cells followed by differentiation into other pancreatic cell types.