Question

Which of the following is true about glucagon and insulin?

• A. They are secreted from the same type of cells and have the same function.
• B. They are secreted from the same type of cells but are opposite in function.
• C. They are secreted by different types of cells but are similar in function.
• D. They are secreted from different types of cells and are opposite in function.

Answer 1

The correct option is D They are secreted from different types of cells and are opposite in function.

Insulin and glucagon are secreted by different cells of the pancreas and have opposite functions. The endocrine cells in the pancreas are the ‘islets of Langerhans’. The two main types of cells in the islet of Langerhans are called $\alpha$-cells and $\beta$-cells. The $\alpha$-cells secrete glucagon, while the $\beta$-cells secrete insulin.

Glucagon increases the blood glucose levels. It acts mainly on the liver cells and stimulates the breakdown of glycogen to form glucose. It also stimulates the process of glucose synthesis. Glucagon reduces the cellular glucose uptake and utilisation.

Insulin decreases the blood glucose levels. It acts mainly on hepatocytes and adipocytes and stimulates uptake and utilization of glucose by these cells. This causes rapid movement of glucose from blood to hepatocytes and adipocytes, resulting in decreased blood glucose levels. Insulin also stimulates the conversion of glucose to glycogen in the target cells.