Glucagon produced by `alpha`-cells of islets of Langerhans

Options

A. Converts glucosse to glycogen
B. Converts glycogen to glucose
C. Decreases concentration of glucose in blood
D. None of these.

Answer

To answer the question regarding the function of glucagon produced by alpha cells of the islets of Langerhans, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Source of Glucagon**:
- Glucagon is produced by the alpha cells of the islets of Langerhans, which are located in the pancreas.

2. **Understand the Function of Glucagon**:
- The primary role of glucagon is to increase blood glucose levels. It does this by promoting the conversion of stored glycogen in the liver into glucose.

3. **Mechanism of Action**:
- When blood sugar levels drop, glucagon is released into the bloodstream. It acts mainly on liver cells (hepatocytes).
- The process that glucagon stimulates is called glycogenolysis, which is the breakdown of glycogen (the stored form of glucose) into glucose.

4. **Differentiation from Insulin**:
- It is important to note that insulin, produced by beta cells of the islets of Langerhans, has the opposite effect. Insulin converts glucose to glycogen (glycogenesis) and decreases blood glucose levels.

5. **Evaluating the Options**:
- The options provided were:
- Converts glucose to glycogen
- Converts glycogen to glucose
- Decrease concentration of glucose in blood
- None of these
- Based on the function of glucagon, the correct answer is "converts glycogen to glucose".

### Final Answer:
The correct option is: **Converts glycogen to glucose**.

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