Structure and Function: Thyroid and Parathyroid Glands

The thyroid and parathyroid glands are situated close to each other in the front of the neck. The thyroid gland produces the hormone thyroxine (T4) and its more active form, T3, which act on body cells to regulate metabolism (the chemical reactions continually occurring in the body). Some thyroid cells secrete the hormone calcitonin, which lowers calcium in the blood. The parathyroid glands produce parathyroid hormone (PTH), the main regulator of calcium.

Structure of the thyroid and parathyroid glands

The thyroid gland is wrapped around the front of the trachea. The four parathyroid glands are at the back of the thyroid gland.

Thyroid and parathyroid hormones

Iodine from the diet is used to make the hormones T4 and T3. These hormones are produced by the thyroid gland and regulate body metabolism. Parathyroid hormone (PTH) and, to a lesser extent, calcitonin regulate levels of calcium and phosphate.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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