3. The thyroid gland, and parathyroid glands
The thyroid gland
The thyroid gland is positioned in the front of the trachea.
It produces and secretes substances important in:
- controlling the metabolic rate
- controlling the rate of normal growth and development in the young
Trace amounts of the chemical iodine are required to produce thyroid hormones. Iodine is therefore stored in the thyroid gland.