This animation shows how your thyroid gland can become underactive, causing a condition known as underactive thyroid hypothyroidism. the navigation arrows below the animation screen to play, pause, rewind or fastforward the animation. This animation contains sound. Here we show the position of the thyroid gland. Your thyroid gland produces two hormones. These hormones are called triiodothyronine T3 and thyroxine T4. The two hormones are released from your thyroid gland and enter your bloodstream. They play an important role in controlling the rate of metabolism, the chemical reactions that take place in your.
Body. The amount of the hormones T3 and T4 that your thyroid gland produces is controlled by the pituitary gland, which is in your brain. Your pituitary gland produces a hormone called thyroid stimulating hormone TSH. TSH stimulates your thyroid gland to produce the thyroid hormones. An underactive thyroid hypothyroidism, is most often caused by a problem in the thyroid gland itself. It can also occur because the pituitary gland isn’t producing enough TSH, but this is less common. Your symptoms will depend on how much of the thyroid hormones your body is producing. You may not notice any symptoms at first. As your thyroid gland.