The thyroid gland is a butterfly shaped organ located in the neck. All vertebrates have a thyroid gland, but it is not always located in the same position. It is an endocrine gland, which means that it is part of the endocrine system and secretes hormones directly into the blood. This organ is probably best known for the conditions hyperthyroidism (overactive gland) and hypothyroidism (underactive gland) that can cause a number of serious symptoms. The thyroid gland has a number of important functions in the body and is essential to life and development.
What does the thyroid gland do?
The primary function of the thyroid gland is to synthesize and secrete two special hormones. The first of these is known as thyroxine (T4) and the second is triiodothyronine (T3). These hormones are synthesized from iodine and an amino acid known as tyrosine. The most active of these hormones is T3 and although T4 has some effect the majority (80%) is converted to T3 by other organs such as the liver and kidney. These hormones act like messengers to deliver instructions to tissues and organs via the blood. The cells then respond by slowing or speeding up their actions. The reason that the thyroid is so important is that responsible for the rate of metabolism in the body. This means it affects every organ, tissue and cell in the body. Some of the roles that the hormones have in the body include controlling:
- How quickly the body uses its available energy (speed of metabolism)
- Protein production
- Body temperature and circulation
- Growth and skeletal development
- Energy levels
- Agility and muscle tone
- Heart rate
- Blood sugar level
- Bowel function
- Cholesterol levels
- Fluid Balance
- Nervous system function
- The regulation of fat, carbohydrate and protein metabolism
Another function of the thyroid is the production of the hormone calcitonin. This hormone helps to regulate the levels of calcium in the body.
Did you know?
The rate of thyroid production is regulated by the pituitary gland. It secrets more thyroid stimulating hormone to increase production or less to reduce production as needed by the body.
Iodine is essential for the proper functioning of the thyroid. If it is lacking in the diet then the gland can become enlarged, a condition known as goiter. Children born to mothers lacking in iodine usually show a deficiency of thyroid hormones, which may impact negatively on their growth, mental capacity and health.