Biochemistry

As part of this complex, thyroid hormones are distributed to different organs and tissues. Upon contact with cells, hormones are cleaved from the “ carrier ” protein, enter the cells through the membrane, and are distributed between cell structures. Thyroid hormones have anabolic effects and are necessary for normal growth, mental and physical development. Almost all body tissues are sensitive to them. Thyroid hormones have a regulatory effect on energy metabolism, mainly on oxidative processes. The increased content of thyroxine in the blood leads to the separation of cellular respiration and phosphorylation: the biosynthesis of macroergic compounds, especially ATP, is disrupted. Most of the energy generated is dissipated in the form of heat, which can cause an increase in body temperature. Thyroid hormones have a pronounced effect on the genetic apparatus of the cell. This is due to its activating effect on the biosynthesis of matrix and ribosomal RNA and, therefore, on the biosynthesis of various proteins. Inactivation of thyroid hormones is carried out mainly in the liver, as well as in peripheral tissues, as a result of deiodination and deamination. The loss of the amino group by the molecules of thyroid hormones occurs during the transamination with a-keto acids, as a result of which inactive pyruvate analogues of thyroid hormones are formed. In case of impaired thyroid function, hypo- or hyperthyroidism is noted . Hypothyroidism is characterized by a low metabolic rate: basic metabolism and body temperature decrease, oxygen consumption decreases. At an early age with hypothyroidism, the development of irreversible changes in the nervous system is possible - cretinism. Congenital hypothyroidism can be caused by several reasons: a violation of the formation of thyroid hormones (including deficiency of iodine in food and water), the functioning of enzymes involved in the biosynthesis of thyroid hormones, disturbances in thyroglobulin proteolysis, etc. The pathological condition for hypothyroidism is called myxedema. With increased thyroid function - hyperthyroidism , a decrease in body weight, sweating, palpitations, increased blood pressure, exophthalmia (exophthalmia) are observed . Hyperglycemia, glucosuria, negative nitrogen balance may also develop. Tissue hormones. In addition to the hormones synthesized by the endocrine glands, there are hormones that are formed in various organs and tissues, as well as in the blood. This group includes kallikreins, angiotensin, prostaglandins, gastrin , secretin, enterogastrin . Some of them form systems. So, kallikrein - the kinin system is represented by peptides that are formed in various organs and tissues, including in the blood. As a rule, they are in an inactive state and are activated under the influence of enzymes catalyzing limited proteolysis reactions. 291