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 need to evaluate each statement provided and determine which one is correct.

### Step-by-Step Solution:

1. **Evaluate the First Statement:**
- The statement claims that "during the time of stress, cortisol acts as an anabolic hormone in muscles and adipose tissue."
- **Analysis:** Cortisol is known to be a catabolic hormone, especially during stress. It promotes the breakdown of proteins and fats to provide energy, rather than building them up.
- **Conclusion:** This statement is **incorrect**.

2. **Evaluate the Second Statement:**
- The statement claims that "the posterior pituitary is connected to the hypothalamus by the portal system."
- **Analysis:** The portal system refers to a network of blood vessels that connects the hypothalamus to the anterior pituitary. The posterior pituitary is connected to the hypothalamus via nerve fibers, not a portal system.
- **Conclusion:** This statement is **incorrect**.

3. **Evaluate the Third Statement:**
- The statement claims that "prolonged lack of iodine has a significant effect on thyroxine secretion."
- **Analysis:** Iodine is an essential component of thyroxine (T4) hormone. A prolonged deficiency in iodine leads to reduced production of thyroxine, which can result in conditions like goiter and hypothyroidism.
- **Conclusion:** This statement is **correct**.

4. **Evaluate the Fourth Statement:**
- The statement claims that "injection of calcitonin causes hypocalcemia."
- **Analysis:** Calcitonin is a hormone that helps lower blood calcium levels. However, it primarily works to decrease calcium levels rather than causing hypocalcemia directly. It regulates calcium levels but does not induce hypocalcemia in the way described.
- **Conclusion:** This statement is **incorrect**.

### Final Conclusion:
The only correct statement among the options provided is the **third statement**: "Prolonged lack of iodine has a significant effect on thyroxine secretion."