Thyroid Hormone Production and Function - Topic Overview
thyroid gland uses iodine from food to make two
thyroid hormones: triiodothyronine (T3) and thyroxine (T4). It also stores
these thyroid hormones and releases them as they are needed. The
hypothalamus and the
pituitary gland, which are located in the brain, help
control the thyroid gland. The hypothalamus releases thyrotropin-releasing
hormone (TRH), which stimulates the pituitary gland to release
thyroid-stimulating hormone (TSH). When the hypothalamus and pituitary are
working normally, they sense when:
- Thyroid hormone levels are low, so they secrete
more TRH and TSH, which stimulates the thyroid to make more
- Thyroid hormone levels are too high, so they secrete
less TRH and TSH, which reduces hormone production by the thyroid.
Disease or tumors of the pituitary gland can affect this
See a picture of
thyroid hormone production .
Thyroid hormones affect every cell and all the organs of the body.
- Regulate the rate at which calories are burned,
affecting weight loss or weight gain.
- Can slow down or speed up the
- Can raise or lower body
- Influence the rate at which food moves through the
- Control the way muscles contract.
Control the rate at which dying cells are replaced.