Receiving Signals from the Pituitary Gland
According to the American Thyroid Association, the thyroid gland receives signals to increase or decrease hormone production based on the levels of hormones circulating in the blood. If there aren't enough thyroid hormones in the blood, your hypothalamus releases thyrotopin-releasing hormone. This signals your pituitary gland to secrete a substance called thyroid-stimulating hormone. TSH stimulates the thyroid gland to produce more hormones. When the levels of thyroid hormones in your blood are adequate, the pituitary gland shuts off its production of TSH. In response to a drop in TSH, the thyroid stops producing the hormones.
Making T3 and T4
When the thyroid gland senses TSH, it starts to make more hormones. Oregon State University says that to produce hormones, the thyroid gland needs iodine from the foods you eat. Within the thyroid gland, iodine is combined with an amino acid called tyrosine. If the iodine joins with three tyrosine molecules, T3 or triiodothyronine is produced. If it combines with four tyrosine molecules, T4 or thyroxine is produced.
Thyroid Hormones Regulate Your Metabolism
As the thyroid gland produces more T3 and T4, they are secreted into the bloodstream and delivered to almost every cell in your body. T3 and T4 are involved in regulating metabolism, digestion, body temperature and growth. These hormones also help the brain, heart, muscles and organs functioning properly. According to the American Association for Clinical Chemistry (AACC), thyroid hormones basically tell your cells how fast to use energy. Your thyroid gland also makes calcitonin. The AACC says calcitonin is "...a hormone that helps to regulate calcium levels in the blood by inhibiting the breakdown (reabsorption) of bone and increasing calcium excretion from the kidneys."
Disease Occurs When the Thyroid Fails
The Mayo Clinic says that if the thyroid gland produces too much of a hormone, you may develop hyperthyroidism. This condition causes your body's metabolism to speed up. You may experience weight loss, fast heart rate, insomnia, tremors and irritability. If the thyroid doesn't produce enough hormone and your levels are chronically low, you may be diagnosed with hyothyroidism. In this situation, your body's metabolism slows. This can lead to weight gain, dry skin, intolerance to cold, fatigue, joint pain and heart disease. Many conditions can interfere with your thyroid's ability to function.
