Question

Write short notes on the functions of Insulin and Glucagon.

Answer 1

Hint: Insulin and glucagon both are hormones that regulate the level of the same substance in the blood but in an antagonistic manner.

Complete Answer:
(I) Insulin and glucagon are the hormones that play an important role in the maintenance of glucose levels in the blood. Both the hormones are produced by different types of cells in the pancreas.
- Insulin is a hormone produced by β-cells of the islets of Langerhans in the pancreas. The stimulus that induces the secretion of insulin is hyperglycemia, the high glucose concentrations in the blood.
- Insulin reduces the blood glucose levels immediately by increasing the transport of glucose in adipose tissue, skeletal muscle cells and liver cells. Insulin stimulates the uptake of the glucose in these cells from the blood. Although it does not affect glucose uptake into the liver directly, it enhances the long-term uptake of glucose as a result of its actions on the enzymes controlling glycolysis, glycogenesis, and gluconeogenesis.
- When the concentration of blood glucose reaches the normal level, the levels of insulin in the blood also become reduced. Type 1 and type 2 diabetes are caused due to deficiency of Insulin.

(II) Glucagon is a hormone produced by the α-cells of the pancreatic islets. and stimulates the breakdown of glycogen. The secretion of glucagon is stimulated by hypoglycemia, the low concentration of glucose in the blood.
- Glucagon mostly affects liver cells. In the liver it stimulates the process of glycogenolysis, i.e., release of glucose from glycogen into the blood-stream. Glucagon also enhances gluconeogenesis from amino acids and lactic acid in the liver.
- Gluconeogenesis is the process in which glucose is synthesized from non-carbohydrate substances. Both processes hepatic glycogenolysis and gluconeogenesis contribute to the hyperglycemic effect of glucagon and causes release of glucose into the blood. The deficiency of Glucagon causes hypoglycemia.

Note: Insulin and glucagon both play an important role in maintaining steady state inside the body i.e. homeostasis. When the sugar level in blood becomes high, the pancreas starts secreting more insulin. And when sugar level in blood is low, the pancreas secretes glucagon in more quantity. In this way a balance in blood glucose level is maintained that provides sufficient energy to the cells for their metabolic activities and also prevents the damages that can happen due to consistent high levels of blood sugar.