Biochemistry

water makes up about 40% of all tissue water, with 10-40% of it being bound by proteins. This water differs in its properties from ordinary: it does not freeze when the temperature drops to 0°C and lower and does not have the properties of a solvent. Most of the water in the body is concentrated between various molecules, membranes, fibrous structures and mechanically fixed, without being part of the hydration shells. Such water is called immobilized. Immobilized water freezes at temperatures below 0°C, dissolves many substances and is easily involved in metabolic reactions. There is a dynamic equilibrium between different types of water, one of its forms can pass into another. So, replenishment of the amount of hydrated water occurs due to immobilized and free water. The amount of water in individual organs and tissues varies depending on their functional state. So, with muscle work, the water content in the muscles increases. This phenomenon is explained by a rush of blood and an increase in the hydrophilicity of the proteins of the working muscles. Water exchange and regulation of water metabolism. The main sources of water for the body are food and drinking water. The water that comes with food is called exogenous and makes up 6/7 of all body water. The rest (1/7) of the total mass of water is formed in human tissues as the final product of the oxidation of nucleic acids, proteins, lipids, carbohydrates. This is endogenous water. It was found that with the complete oxidation of 100 g of fat, the body receives 107.1 g, carbohydrates - 55.6 g and proteins 41.3 g of water. Every day, an adult needs about 2.5-3 liters of water. However, this amount can vary greatly depending on the person ’ s age, nature of his work, ambient temperature and type of food. Typically, about 1 liter of water is introduced into the body as part of the so-called solid food (bread, meat, potatoes, etc.), the rest is in the form of drink (water, tea, soup, milk, etc.) and liquid dishes. The exchange of water in the body is part of the general metabolism and is closely related to the exchange of nucleic acids, proteins, lipids and carbohydrates. Kidneys, lungs, skin, and the canal participate in water metabolism. Water is absorbed by the mucous membrane of the alimentary canal along its entire length, but mainly in the colon. Water molecules along with digested substances penetrate deep into the epithelial cells of the mucous membranes as a result of diffusion and osmosis, as well as partially through active transport, which is carried out by blood proteins - albumin and globulins. Water is excreted from the body mainly with urine - about 1.2-1.5 liters, which is about 60% of all excreted water. A small amount of it, about 0.2-0.3 liters, is secreted through the lungs during breathing. This is due to the fact that 22