So far we talked about the structure and activities of agencies that provide assimilation, i.e. the absorption of nutrients and oxygen. Along with assimilation, in the body is constantly going on and the destruction process of splitting of living matter, the formation of chemical compounds that have toxic properties, accumulation of which leads to poisoning. These include, for example, ammonia (NH3)resulting from the exchange of protein, lactic acid produced during muscle work, and many other substances. On the other hand, with food can do some substances in excessive quantities or completely unnecessary or even harmful. In all these cases, the body must ensure the elimination of unnecessary chemical products, and this is achieved total activity of many organs.
For example, all the water-insoluble substances excreted through the intestine, from faeces; gaseous products, such as carbon dioxide and water vapor, some drugs, alcohol, stand out light. Some substances, in particular drug, derived mucosa of the gastrointestinal tract. Water and dissolved in it substances excreted in the urine by the kidneys, then, through the sweat glands of the skin *, with milk and saliva. However, along with the elimination of harmful substances, excretory organs carry out one more important task - preservation of a constancy of the internal environment of the body - blood and tissue fluid around every cell of our body. The fact that the most complicated chemical processes which ensure the functioning of the body are normal only in conditions of constant (stable) relations between all the many substances that are part of these fluids. Violation of these correlations leads to serious disorders of the main vital functions of the organism. Unable to go into detail on this complex issue, we will try to illustrate its value is one example. It is known that the most important part of any living organism is water. Life on our planet was born in water, and all the life processes of any body occur in the water, so water is the main mass of every cell, tissue and organism. The total number of its body is about 70%. This means that the body weight is 75 kg contains about 53 kg of water! "It would seem, " wrote Professor A. G. Genetiski, that with such a large supply of the body can easily cope with the loss of a quantity of water or a small excess. In reality, however, the excess or shortage of water, accounting for only 1% of the total amount, i.e. about 0.5 l, already causes significant health problems". Of all the agencies involved in the administration of excretory functions, the most important aspect of the urinary system (Fig. 19), which consists of the kidneys, ureters, bladder and urethra.
Fig. 19. Urinary system:
Want to delete products are excreted in the urine, which is formed by the kidney, and the rest of the bodies above this system are used only for carrying out urine. Kidneys, therefore, are the main body of the urinary system; in the excretion of a number of substances and especially in the regulation of the constancy of the internal environment of the body they are indispensable.
* In the skin of the adult person has about 2.5 million sweat glands, which are distributed; their greatest number is in the areas of maximum friction: the palms, armpits, on the soles. These glands during the day in the conditions of temperate climate emit approximately 500-600 ml of sweat.