Choose the CORRECT statement amongst the following.

Options

A. During the time of stress , cortisol acts as an anabolic hormone in muscle and adipose tissue
B. The posterior pituitary is connected to hypothalamus by a portal system
C. Prolonged lack of iodine has a significant effect on thyroxine secretion
D. Injection of calcitonin causes hypocalcaemia

Answer

To solve the question, we will analyze each of the provided statements one by one to determine which one is correct.

### Step-by-Step Solution:

1. **Statement 1: "During the time of stress cortisol acts as an anabolic hormone in muscles and adipose tissue."**
- **Analysis:** This statement is incorrect. Cortisol is primarily a catabolic hormone, meaning it promotes the breakdown of molecules. It increases the basal metabolic rate (BMR) and mobilizes energy stores, leading to the breakdown of proteins and fats rather than building them up.
- **Conclusion:** This statement is false.

2. **Statement 2: "The posterior pituitary is connected to the hypothalamus by a portal system."**
- **Analysis:** This statement is also incorrect. The anterior pituitary is connected to the hypothalamus via a portal system (the hypothalamic-pituitary portal system). In contrast, the posterior pituitary is connected to the hypothalamus through hypothalamic neurons (axons).
- **Conclusion:** This statement is false.

3. **Statement 3: "Prolonged lack of iodine has a significant effect on thyroxine secretion."**
- **Analysis:** This statement is misleading. A prolonged lack of iodine leads to insufficient production of thyroxine, which can cause the thyroid gland to swell (goiter) in an attempt to absorb more iodine. However, the statement implies a significant effect, which is not accurately described as the secretion of thyroxine is severely impaired due to iodine deficiency.
- **Conclusion:** This statement is false.

4. **Statement 4: "Injection of calcitonin causes hypocalcemia."**
- **Analysis:** This statement is correct. Calcitonin is a hormone secreted by the thyroid gland that lowers blood calcium levels (hypocalcemia) by promoting the deposition of calcium in bones and reducing calcium absorption in the intestines.
- **Conclusion:** This statement is true.

### Final Answer:
The correct statement is **Statement 4: "Injection of calcitonin causes hypocalcemia."**

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