Question

Iodine is a component of which one of the following endocrine glands?

• A. Pituitary gland
• B. Thyroid gland
• C. Adrenal gland
• D. Hypothalamus

Hint:

Iodine $\rightarrow$ Essential for Thyroid hormones ($T_3$ and $T_4$). Deficiency causes Goitre and Cretinism.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Iodine is an essential trace mineral required for the biosynthesis of thyroid hormones that regulate basal metabolic rate.
Key Formula or Approach:
\[ \text{Thyroglobulin} + \text{Iodine} \longrightarrow \text{Thyroxine } (\text{T}_4) + \text{Triiodothyronine } (\text{T}_3) \]

Step 2: Detailed Explanation:
The Thyroid gland actively traps circulating iodide ($I^-$) from the bloodstream via sodium-iodide symporters (NIS).
Thyroid peroxidase incorporates iodine into tyrosine residues of thyroglobulin to synthesize the iodinated hormones:
- Triiodothyronine ($\text{T}_3$, containing 3 iodine atoms)
- Thyroxine ($\text{T}_4$, containing 4 iodine atoms)
Dietary iodine deficiency causes compensatory thyroid hypertrophy (endemic goitre).

Step 3: Final Answer:
Hence, Iodine is a component of the Thyroid gland, corresponding to option (B).