what does this gland do?
The primary function is the production of the iodine-containing thyroid hormones, triiodothyronine (T) and thyroxine (T) and the peptide hormone calcitonin.
Thyroid
he primary function of the thyroid is the production of the iodine-containing thyroid hormones, triiodothyronine (T) and thyroxine (T) and the peptide hormone calcitonin. 
where is thyroid gland situated in human body Neck
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Thyroid [SEP] Thyroid hormones
The primary function of the thyroid is the production of the iodine-containing thyroid hormones, triiodothyronine (T) and thyroxine (T) and the peptide hormone calcitonin. The thyroid hormones are created from iodine and tyrosine. T is so named because it contains three atoms of iodine per molecule and T contains four atoms of iodine per molecule. The thyroid hormones have a wide range of effects on the human body. These include: After secretion, only a very small proportion of the thyroid hormones travel freely in the blood. Most are bound to thyroxine-binding globulin (about 70%), transthyretin (10%), and albumin (15%). Only the 0.03% of T and 0.3% of T traveling freely have hormonal activity.