The thyroid is an organ that is considered part of the endocrine, or hormone, system. It is located in the neck below the Adam's apple. The thyroid's main purpose is to produce thyroid hormones. These hormones then travel through the bloodstream to all the other tissues and organs to help control metabolism in adults and growth, development, and metabolism in children.
- The thyroid is shaped like a butterfly. The two "wings" of the butterfly are the right and left lobes of the thyroid, with lie on both sides of the trachea or main breathing tube. The connection between the wings is called the isthmus.
- The two hormones that the thyroid produces are L-thyroxine (T4) and
- The thyroxine (T4) and tri-iodothyronine (T3) hormones regulate your body's metabolic functions such as heat
generation, and the utilization of carbohydrates, proteins, and fats. In
children, thyroid hormones are responsible for growth and development.
- Regulatory hormones from different parts of the brain control the thyroid's production of T4 and T3. In the pituitary gland, thyrotropin-stimulating hormone (TSH) is released when more thyroid hormone is needed and travels via the bloodstream to the thyroid gland. TSH then stimulates the thyroid to produce T4 and T3.
- The pituitary gland acts like a thermostat. When there is too much
thyroid hormone in the bloodstream, the pituitary releases less TSH to
signal the thyroid to produce less thyroid hormone. When there is too
little thyroid hormone in the bloodstream, the pituitary releases more
TSH to signal the thyroid to increase thyroid hormone production.
Through this "feedback" system, the production of thyroid hormone is
Location and picture of the thyroid gland.
Note two lobes of the thyroid, similar to butterfly wings.
Stephanie L Lee, MD, PhD, FACE
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