..... Click the link for more information. and small quantities of the other closely related thyroid hormones. The amount of thyroxine production (and therefore the metabolic rate) is dependent on a sufficient intake of iodine and on stimulation by thyroid-stimulating hormone (TSH) from the pituitary gland pituitary gland, small oval endocrine gland that lies at the base of the brain . It is sometimes called the master gland of the body because all the other endocrine glands depend on its secretions for stimulation (see endocrine system ).
..... Click the link for more information. . Metabolic disorders result when the thyroid secretes too little or too much thyroxine. Deficiencies in thyroid secretion (hypothyroidism) occur when there is insufficient iodine in the diet. A disease known as goiter results from the deficiency, although it has been virtually eliminated by the use of iodized salt. Hypothyroidism that results from glandular malfunction is known as myxedema in the adult and cretinism cretinism (krē`tənĭz'əm), condition produced in infants and children due to lack of thyroid hormone.
..... Click the link for more information. in infancy and childhood. Treatment is by administration of thyroxine. Excessive secretion of thyroxine, or hyperthyroidism, causes an increased metabolic rate, loss of weight despite good appetite, protrusion of the eyeballs, rapid pulse, and irritability. The condition, also known as Graves' disease, may be accompanied by enlargement of the thyroid. The thyroid gland also produces the hormone calcitonin, which is involved in the regulation of serum calcium in the body. See also endocrine system endocrine system (ĕn`dəkrĭn)
..... Click the link for more information. .
thyroid gland
Endocrine gland in the throat that secretes hormones vital to metabolism and growth. Secretion of thyroid hormones—mostly thyroxine (T4)—is controlled by thyroid-stimulating hormone (TSH), released by the pituitary gland when the level of thyroid hormones in the blood drops below a certain threshold (see endocrine system). These hormones' primary action in adults is to regulate cellular oxygen consumption (metabolic rate). They also lower blood cholesterol and are necessary for normal growth and development in children. The thyroid also produces calcitonin, a hormone that stimulates deposition of calcium from the blood into the bones, balancing the action of parathyroid hormone. See also goitre; Graves disease; iodine deficiency.
thyroid gland
thyroid gland [′thī‚rȯid ‚gland]
Thyroid gland
An endocrine gland found in all vertebrates that produces, stores, and secretes the thyroid hormones. In humans, the gland is located in front of, and on either side of, the trachea (see illustration). Thyrocalcitonin, one hormone of the thyroid gland, assists in regulating serum calcium by reducing its levels. The iodine-containing hormones thyroxine and triiodothyronine regulate metabolic rate in warm-blooded animals and are essential for normal growth and development. To produce these, the thyroid gland accumulates inorganic iodides from the bloodstream and unites them with the amino acid tyrosine. This activity is regulated by thyrotropic hormone from the anterior lobe of the pituitary gland. See Thyroid hormone, Thyroxine
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