Following are events taking place for blood glucose regulation -
(i) increase in blood glucose
(ii) increase in circulating from glucagon
(iii) release of glucose from glycogen
(iv) decrease in blood glucose level
Select the option depicting the correct sequence of these events.

Options

A. (iv), (iii) , (ii) , (i)
B. (iii), (i) , (ii) , (iv)
C. (iv), (ii) , (iii) , (i)
D. (i), (ii) , (iv) , (iii)

Answer

To solve the problem regarding the sequence of events for blood glucose regulation, we need to analyze the events given in the question:

1. **Increase in blood glucose** (Event i)
2. **Increase in circulating glucagon** (Event ii)
3. **Release of glucose from glycogen** (Event iii)
4. **Decrease in blood glucose level** (Event iv)

Now, let's determine the correct sequence of these events step by step:

### Step 1: Identify the Trigger
The process begins when there is a **decrease in blood glucose levels**. This typically occurs during fasting or prolonged exercise when the body needs more glucose for energy.

### Step 2: Hormonal Response
In response to low blood glucose levels, the pancreas releases **glucagon**. This is a hormone produced by the alpha cells of the pancreas and is responsible for raising blood glucose levels.

### Step 3: Glycogenolysis
Once glucagon is released into the bloodstream, it stimulates the liver to convert stored glycogen into glucose through a process called **glycogenolysis**. This means that glucose is released from glycogen stores in the liver.

### Step 4: Increase in Blood Glucose
As glucose is released into the bloodstream, the blood glucose levels begin to **increase**. This is the final step in the sequence, where the body returns to homeostasis.

### Conclusion
Now, putting these steps together, the correct sequence of events is:
1. Decrease in blood glucose level (Event iv)
2. Increase in circulating glucagon (Event ii)
3. Release of glucose from glycogen (Event iii)
4. Increase in blood glucose (Event i)

Thus, the correct order of events is:
**Decrease in blood glucose level → Increase in circulating glucagon → Release of glucose from glycogen → Increase in blood glucose.**

### Final Answer
The correct sequence of these events is: **iv → ii → iii → i.**

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