Biochemistry

addition to the thyroid gland, a significant amount of iodine contains the adrenal cortex, liver, spleen, lungs, and other organs of animals and humans. A decrease in the activity of the thyroid gland associated with a lack of iodine in food and drinking water causes a serious illness - endemic goiter. The risk of developing diseases caused by iodine deficiency is more than 1.5 billion people on Earth, and 150 million people already suffer from endemic goiter. The term "endemic" indicates the confinement of diseases to certain geographical areas. The fact is that some areas arb characterized by low iodine content in soils, waters and plant products, including animal feed. In Ukraine, areas of Transcarpathia and Donetsk region are unfavorable on this basis. Farm animals — mammals and birds — are very sensitive to iodine deficiency. In cows with iodine deficiency, fertility decreases, in sheep a sharp growth lag is observed, in birds egg production decreases. To prevent iodine deficiency, a small amount of this element is added to food and animal feed (15-20 mg of Nal or KI to 1 kg of table salt). Iodine preparations as antiseptics in medical practice began to be used in the second half of the nineteenth century. Nowadays, tincture of iodine (its 5% alcohol solution) is an obligatory accessory of any first-aid kit. But, using iodine, it must be remembered that in large doses it causes bums and poisoning. With prolonged use of iodine preparations, the phenomenon of iodism can occur - inflammation of the mucous membranes of the nose, larynx, frontal sinuses, swelling of the tonsils and salivary glands. The patient suffers from increased nervous excitability, insomnia, and exhaustion of the body. An even greater danger to the body is the radioactive isotope iodine-131 ( >21 I), which is a f- and ү -emitter with a half-life of 8.14 days. Environmental pollution with this isotope can be observed, for example, in violation of the rules for the disposal of radioactive waste. Its biological effect is due to selective irradiation of the thyroid gland and damage to its tissues. At high doses of l3l I in animals and humans, symptoms of radiation sickness are also observed, affecting also the parathyroid and sometimes salivary glands. Iron. The chemical element, in reserves in the - earth's crust, takes fourth place after oxygen, silicon and aluminum. The most important source of iron is minerals. In biological media, iron, as a rule, exhibits an oxidation state of +2 or +3, forming complexes with bioorganic molecules. Iron-containing complexes of the body are responsible for the transport and storage of oxygen, for the transfer of electrons in redox reactions and other key biochemical processes. One of the most famous compounds of Fe (II) is the respiratory blood pigment hemoglobin and myoglobin protein located in the muscles. In the 13