Thyroid (thyroid) gland gets its name from the Greek words tireos - shield and idos-view. It is on the front of the neck in front of the larynx and trachea rings. It consists of two thyroid lateral lobes and the isthmus occasionally occurs in some people extra slice. Gland tissue consists of many small bubbles (follicles). In the follicle accumulates iodine, which comes into contact with food and water. Thyroid weight about 25 grams.
Thyroid gland - this is one of the most important organs of internal secretion. It produces thyroid hormones (thyroid hormones). Thyroid hormones have an effect on virtually all types of metabolism and affect all the organs and tissues.
The thyroid gland secretes mainly two types of hormones: triiodothyronine (T3) and thyroxine tetraiodothyronine or (T4). The blood is usually greater than 95% of thyroxine and triiodothyronine about 5%. Both of these substances are formed in the follicles of the thyroid gland of iodine and one of the essential amino acids - tyrosine.
The daily human need for iodine is 200-220 micrograms. If a person does not get enough iodine from food and water, then after a while disturbed synthesis of thyroid hormones and reduced their number in the blood. The capture of iodine from the blood, the synthesis and secretion of hormones regulated by the pituitary hormone - thyrotropin, the amount of which in turn is controlled by the hormones of the hypothalamus - and tireoliberina tireostatina.
When the amount of thyroid hormones in the blood decreases in the hypothalamus, located in the brain released tireoliberin, which stimulates the production of TSH from the pituitary gland. A thyroid-stimulating hormone stimulates directly the synthesis of thyroid hormones.
In addition to the regulation of thyroid function are involved and other parts of the brain, and these complex processes are not yet fully understood.
In addition to the thyroid gland and affect other organs of internal secretion, and their hormones. Thyroid hormones are released into the bloodstream, are transported through the body by special transport proteins of blood plasma. Then, thyroid hormones cross the membranes of target cells and affect all types of metabolism.
Under the influence of thyroid hormones amplify all aspects of carbohydrate metabolism, increased glucose absorption in the gastrointestinal tract, increasing the effect of insulin. Enhanced synthesis and more fat breakdown, which manifests a decrease in reserve of body fat and weight loss. Accordingly, with decreasing amounts of thyroid hormone increases body weight. There is a growing exchange of body protein.
Excessive thyroid hormone function can be signs of protein deficiency, which manifests the weakness and decreased muscle mass. Excessive function of thyroid hormones increase the body's need for vitamins. Enhancing all types of metabolism is accompanied by increased tissue demand for oxygen, increases heat production.
Thyroid hormones are necessary for normal mental development of man. With their failure in childhood child lags behind not only physically, but also in mental development. In adults, it is shown slowing of mental processes, reduction of memory. Another hormone produced by special parafollicular cells, which are located in the space between the bubbles (follicles) and is called tireokaltsitonin. He has been involved in the regulation of calcium metabolism.
Thyroid diseases are among the most frequent endocrine diseases. Increase or decrease in the thyroid gland diagnosed in 2% of the adult population. In addition, there are diseases of the thyroid gland, which do not show an increase or decrease its function. Almost all thyroid diseases begin quietly and continuously occur without marked clinical manifestations.