Hormones of thyroid and parathyroid glands

Hormones of thyroid and parathyroid glands

The thyroid gland produces the hormones thyroxine and triiodothyronine. Both hormones have a similar multifaceted effect on the body, increases need tissues of oxygen, increase energy processes, stimulate growth and differentiation of tissues, affect the functional state of the nervous and cardiovascular systems, liver, kidneys and other organs, increase the absorption of glucose and its utilization. The effect of thyroid hormones may vary depending on the dose. So, small doses of thyroxine have an anabolic effect, large doses lead to increased protein breakdown. In high doses, thyroid hormones inhibit the feedback mechanism of the pituitary thyroid stimulating activity.

Triyodtironin 3-5 times more active than thyroxine, and operates faster as less of proteins associated with blood (circulates in blood mainly in free form), and quickly penetrate the cell membrane. The latent period triyodtironina is equal to 4-8 h, and tiroksina 24-48 h In clinical practice using synthetic analogues of thyroxine (levothyroxine) and triiodothyronine (liothyronine). Prescribed levothyroxine and liothyronine (in relatively small doses) in case of insufficient function of the thyroid gland and in higher doses (not causing hyperthyroidism, but sufficient to suppress thyroid-stimulating activity) when excess thyroid-stimulating pituitary function. To fill the deficit of iodine in the composition of these products often include potassium iodide or designate it further. Also used a combination of drugs containing thyroid hormones and in some cases the addition of potassium iodide.

Antagonists of thyroid hormones are antithyroid drugs.

Hyperproduction of thyroid hormone — thyroxine leads to the development of severe disease (thyrotoxicosis, Graves ' disease, thyrotoxic goiter), which is treated with drug therapy, surgery or combinations thereof.

Antithyroid drugs (pharmacotherapy) for the treatment of hyperthyroidism is widely used. One of the main synthetic means the group is tiamazol, but so are propylthiouracil and some other drugs. The mechanism of action is associated with a decrease in the iodination of thyroxine in the thyroid gland by the blockade of the inclusion of iodine atoms to the molecule of thyroxine. They accelerate the excretion from the thyroid gland of iodide inhibit the activity of enzyme systems involved in the oxidation of iodides with inhibition of iodination of thyroglobulin and delay the conversion of diyodtirozina three and tetrajodtironina, or inhibition of release of thyroid stimulating hormone.

The thyroid gland also produces calcitonin — a hormone gipokaltsiemicheskogo action. Currently known 8 types of calcitonin, of which medical importance calcitonin salmon, pigs and humans (see PROOFREADERS METABOLISM of BONE AND CARTILAGE). Calcitonin is produced by parafollicular cells of the thyroid gland and cells of the thymus and parathyroid glands. The technology of production of synthetic calcitonin.

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