The thyroid gland is a small, butterfly-shaped organ in your throat, and it is very important to your health and well-being. The thyroid is part of the endocrine system, which is essentially a collection of glands. Your thyroid produces hormones that regulate growth, maturation, and metabolism.
Thyroid gland uses iodine to make thyroid hormone. Iodine comes from food, mainly seafood and dairy products. It is also added to salt since it can be hard to get enough from food. The function of the thyroid gland is to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3).
Thyroid cells are the only cells in the body which can absorb iodine. These cells combine iodine and the amino acid tyrosine to make T3 and T4. T3 and T4 are then released into the blood stream and are transported throughout the body where they control metabolism (conversion of oxygen and calories to energy).
Every cell in the body depends upon thyroid hormones for regulation of their metabolism. Thyroid hormones affect every cell and all the organs of the body.
They:
• Regulate the rate at which calories are burned, affecting weight loss or weight gain
• Can slow down or speed up the heartbeat
• Can raise or lower body temperature
• Influence the rate at which food moves through the digestive tract
• Control the way muscles contract
• Control the rate at which dying cells are replaced
• Central nervous system
• Reproductive system and menstrual cycles
• Cholesterol levels
• Fat, carbohydrate and protein metabolism.
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 hormones.
• 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 process.
Another hormone that’s produced in your thyroid gland is called calcitonin. The biological role of calcitonin is not as well understood as that of T3 or T4. Because of this, calcitonin is often neglected in discussions about thyroid hormones. This hormone, secreted by a small population of cells known as C cells, is involved in regulating the level of calcium and phosphate in your blood. Calcium and phosphate are both involved in the formation of bones.
References:
http://www.webmd.com/women/tc/thyroid-hormone-production-and-function-topic-overview
https://www.endocrineweb.com/conditions/thyroid/how-your-thyroid-works
http://www.mydr.com.au/health-images/thyroid-gland-and-thyroid-hormones
