Final answer:
The thyroid gland produces and stores thyroid hormones, including thyroxine (T4) and triiodothyronine (T3). These hormones are synthesized from tyrosine in the presence of iodine and are stored in colloid within the thyroid follicles. When needed, the hormones are released into the bloodstream for transport.
Step-by-step explanation:
The thyroid gland is responsible for producing and secreting thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3).
Thyroid hormones are synthesized from the amino acid tyrosine in the presence of iodine. Iodine ions are actively transported into the thyroid gland, where they are converted to active iodine by an enzyme called thyroperoxidase.
The thyroid gland consists of follicles that contain a viscous fluid called colloid. Inside these follicles, thyroid hormones are stored as thyroglobulin, a glycoprotein precursor. When needed, thyroid hormones are released into the circulatory system for transport throughout the body.