Pancreas is a composite gland.
It acts as both exocrine and endocrine gland.
The endocrine pancreas consists of ‘Islets of Langerhans’.
There are about 1 to 2 million Islets of Langerhans in a normal human pancreas representing only 1 to 2 per cent of the pancreatic
In the Islet of Langerhans, two main types of cells are called α-cells and β-cells.
The α-cells secrete a hormone called glucagon.
The β-cells secrete insulin.
Glucagon is a peptide hormone.
It plays an important role in maintaining the normal blood glucose levels.
Glucagon acts mainly on the liver cells (hepatocytes) and stimulates glycogenolysis resulting in an
increased blood sugar (hyperglycemia).
Insulin acts mainly on hepatocytes and adipocytes (cells of adipose tissue), and enhances cellular glucose
uptake and utilisation.
Insulin stimulates conversion of glucose to glycogen (glycogenesis) in the target cells.
Prolonged hyperglycemia leads to a complex disorder called diabetes mellitus.
It is associated with loss of glucose through urine and formation of harmful compounds known as ketone bodies.
Diabetic patients are successfully treated with insulin therapy.