The thyroid regulates the metabolism of all cells in the body.
The pituitary and thyroid glands are components of the body's endocrine system, which secretes hormones to regulate body processes (such as those involved in cell growth, immunity and reproduction). Although the pituitary and thyroid glands have their own individual functions, they also interact with each other.
Pituitary Gland Functions
The pituitary gland is about the size of a pea, and is attached the hypothalamus, which is a part of the brain located just above the brain stem. It regulates the other glands in the endocrine system, including the thyroid gland.
In addition to its role as a regulator, it produces several hormones: growth hormones that regulate the body's development; prolactin, which initiates milk production in new mothers; luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which stimulate the testes and ovaries; adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands; melanocyte-stimulating hormone, which controls pigmentation of the skin; antidiuretic hormone (ADH), which increases the reabsorption of water in the kidneys; oxytocin, which causes the uterus to contract during childbirth; and thyroid-stimulating hormone (TSH), which stimulates the thyroid gland.
Thyroid Gland Functions
The thyroid weighs about an ounce, and is located in the front of the throat, just below the larynx. The thyroid regulates the metabolism, or chemical activity, of every cell in the body. It also regulates the amount of calcium in the body.
The cells of the thyroid gland are the only cells that can absorb iodine. By combining this element with an amino acid called tyrosine, the thyroid produces the hormones triiodothyronine (T3) and thyroxine (T4). These hormones control the body's metabolism.
Interaction of the Pituitary and Thyroid Glands
The pituitary gland acts as a regulator or controller of the thyroid gland, in much the same way that a thermostat regulates an air conditioning system. The pituitary gland monitors the levels of T3 and T4 hormones in the blood; when they drop too low, it increases its production of TSH, stimulating the thyroid gland to increase production of T3 and T4. When T3 and T4 levels return to normal, the pituitary gland suppresses production of TSH.
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