What is the thyroid gland?

The thyroid gland is an organ that is considered to be part of the endocrine system. The endocrine system is made up of a number of different glands situated in different locations in the body. These glands function to produce biochemical substances called hormones that enter the bloodstream and travel throughout the body. Most of these hormones exert different effects in different tissues throughout the body to help regulate the metabolism, chemical balance, and reproductive function of the body. Other glands that make up the endocrine system include the pituitary gland, the parathyroid glands, the adrenal glands, the ovaries, the testicles, and the pancreas.

Where is it located?

The thyroid gland is located in the lower front part of the neck, just below the Adam\'s apple and above the top edge of the breastbone. It is made up of two lobes which are designated as the right lobe and the left lobe. These lobes are connected by a narrow band called the isthmus. A thin band of tissue called the pyramidal lobe extends upward from the isthmus. The overall configuration resembles a butterfly with the lobes representing the two wings. The thyroid gland wraps around portions of the larynx (voice box) and trachea (windpipe) that pass through the lower front part of the neck. The lobes are usually tucked behind the angular muscles in the neck that are connected to the top edge of the breastbone. It is usually difficult to see the outlines of the thyroid gland beneath the skin, though they may become more apparent if there is enlargement of one or both lobes.

What does it do?

The thyroid gland functions to produce thyroid hormone, a biochemical substance that enters the bloodstream and travels throughout the body to exert effects in a number of different organs and tissues. Thyroid hormone helps to regulate the body temperature and the overall rate of metabolism and energy expenditure. It also helps to maintain normal functioning of the cardiovascular system and the central nervous system. The thyroid gland itself is regulated by a hormone produced by the pituitary gland called TSH. In response to signals provided by TSH, the thyroid hormone takes up iodine and uses it to produce two forms of thyroid hormone called T3 and T4. Both T3 and T4 are released into the bloodstream. Most of the T4 that is released is eventually converted to T3, which is the form of thyroid hormone that is most active in different organs and tissues throughout the body.

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