Q. What are the hormones secreted by the thyroid gland? What are their functions?
The thyroid secretes the triiodothyronine (T3), hormones thyroxine (T4) and calcitonin.
T3 and T4 are iodinated substances derived from the amino acid tyrosine. They act to increase the cellular metabolic rate of the body metabolism of proteins, cellular respiration and lipids, and so on. Calcitonin inhibits the release of calcium cations by the bones therefore controlling the blood level of calcium.