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 about the hypothalamus are true, let's analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement 1: "It is situated at the base of rhombencephalon."**
- This statement is **false**. The hypothalamus is located at the base of the diencephalon, not the rhombencephalon. The rhombencephalon forms the hindbrain, while the hypothalamus is part of the forebrain.

2. **Statement 2: "It has a center for breathing and respiration."**
- This statement is **false**. The centers for breathing and respiration are primarily located in the pons and medulla oblongata, which are parts of the hindbrain. The hypothalamus does not control these functions directly.

3. **Statement 3: "It has centers for control of body temperature, eating, and drinking."**
- This statement is **true**. The hypothalamus plays a crucial role in regulating body temperature, hunger, and thirst. It contains specific nuclei that are responsible for these functions.

4. **Statement 4: "It is connected to the posterior pituitary with the help of the hypothalamo-hypophysal portal system."**
- This statement is **false**. The hypothalamus is connected to the anterior pituitary via the hypothalamo-hypophysial portal system. The posterior pituitary is connected to the hypothalamus through nerve fibers, not through this portal system.

### Summary of True Statements:
- Only **Statement 3** is true regarding the hypothalamus.