Final answer:
T3 and T4 hormones, essential for bodily functions, are produced by the thyroid gland and require iodine for their synthesis.
Step-by-step explanation:
Unlike other hormones, T3 and T4 hormones require iodine for production. The hormones secreted by the thyroid gland include Thyroxine (T4) and Triiodothyronine (T3) which are synthesized from tyrosine in the presence of iodine. The thyroid follicles actively transport iodine ions from the bloodstream into the follicle cells, resulting in a concentration that is significantly higher than that of the blood. This process is vital for the synthesis of T3 and T4, which are essential for the regulation of the body's basal metabolic rate.