The thyrotropin releasing hormone (TRH) from the `ul(" (1) ")` stimulates the `ul(" (2) ")`to secrete the thyroid stimulating hormone (TSH), which in turn stimulates the thyroid gland to secrete thyroxine. A `ul(" (3) ")` amount of thyroxine in the blood exerts `ul(" (4) ")`effect on (1) so that `ul(" (5) ")` TRH and TSH are produced. This eventually `ul(" (6) ")` the amount of thyroxine. It is called `ul(" (7) ")` feed back control.
Select the option that correctly fills up the blanks in the above passage.

Options

A. (1)-Posterior lobe of pituitary gland, (2)-Hypothalamus, (3)-Low (4)-Inhibitory, (5)-Lesser, (6)-Decreases, (7)-Negative
B. (1)-Hypothalamus, (2)-Posterior lobe of pituitary gland, (3)-Low, (4)-Stimulatory, (5)-More, (6)- Increases, (7)-Positive
C. (1)-Hypothalamus, (2)-Anterior lobe of pituitary gland, (3)-High, (4)- Inhibitory, (5)-Lesser, (6)-Decreases, (7)-Negative
D. (1)-Anterior lobe of pituitary gland, (2)-Hypothalamus, (3)-High, (4)-Stimulatory, (5)-More, (6)- Increases, (7)-Positive

Answer

To solve the question, we need to fill in the blanks in the passage with the appropriate terms related to the hormonal regulation of thyroxine secretion. Let's break it down step by step:

1. **Identify the source of TRH (Thyrotropin Releasing Hormone)**:
- TRH is released from the **hypothalamus**.
- **Fill in the blank (1)**: Hypothalamus

2. **Identify the target of TRH**:
- TRH stimulates the **anterior lobe of the pituitary gland** to secrete TSH (Thyroid Stimulating Hormone).
- **Fill in the blank (2)**: Anterior lobe of pituitary gland

3. **Identify the effect of TSH**:
- TSH stimulates the thyroid gland to secrete **thyroxine**.
- **Fill in the blank (3)**: High amount

4. **Determine the effect of thyroxine on TRH production**:
- A high amount of thyroxine in the blood exerts an **inhibitory effect** on the hypothalamus.
- **Fill in the blank (4)**: Inhibitory effect

5. **Determine the consequence of this inhibitory effect**:
- This inhibitory effect leads to **less** TRH and TSH being produced.
- **Fill in the blank (5)**: Less

6. **Identify the final effect on thyroxine levels**:
- This eventually **decreases** the amount of thyroxine.
- **Fill in the blank (6)**: Decreases

7. **Identify the type of feedback control**:
- This mechanism is known as **negative feedback control**.
- **Fill in the blank (7)**: Negative feedback

Putting it all together, the filled passage would read:

"The thyrotropin releasing hormone (TRH) from the **(1) hypothalamus** stimulates the **(2) anterior lobe of pituitary gland** to secrete the thyroid stimulating hormone (TSH), which in turn stimulates the thyroid gland to secrete thyroxine. A **(3) high** amount of thyroxine in the blood exerts **(4) inhibitory** effect on **(1) hypothalamus** so that **(5) less** TRH and TSH are produced. This eventually **(6) decreases** the amount of thyroxine. It is called **(7) negative** feedback control."