Which of the following statements are true regarding the hypothalamus?

Options

A. It is situated at the base of rhombencephalon.
B. It has centres for breathing and respiration.
C. It has centres which control body temperature, urge for eating and drinking.
D. It is connected to the posterior pituitary with hypothalamo-hypophyseal portal system.

Answer

To determine which statements regarding the hypothalamus are true, let's analyze each option step by step:

1. **Statement 1: It is situated at the base of rhombencephalon.**
- The hypothalamus is not located at the base of the rhombencephalon. Instead, it is situated below the thalamus and above the pituitary gland, which is part of the diencephalon. Therefore, this statement is **false**.

2. **Statement 2: It has centers for breathing and respiration.**
- The control of breathing and respiration is primarily managed by the medulla oblongata, not the hypothalamus. The hypothalamus does not have centers specifically for these functions. Thus, this statement is also **false**.

3. **Statement 3: It has centers which control body temperature, urge for eating and drinking.**
- This statement is true. The hypothalamus plays a crucial role in regulating body temperature, hunger, and thirst. It contains specific centers that monitor and control these vital functions. Therefore, this statement is **true**.

4. **Statement 4: It is connected to posterior pituitary with hypothalamohypophyseal portal system.**
- The hypothalamus is connected to the posterior pituitary gland, but not via the hypothalamohypophyseal portal system. Instead, it connects through nerve fibers. The hypothalamohypophyseal portal system connects the hypothalamus to the anterior pituitary. Thus, this statement is **false**.

Based on this analysis, the only true statement regarding the hypothalamus is **Statement 3**.

### Summary of True Statements:
- **True Statement:** It has centers which control body temperature, urge for eating and drinking.