In a human body as a result of biochemical oxidation disintegration products are formed: water, carbon dioxide, salts of nitrogen, phosphorus and some other substances. Carbon dioxide and vapors of water are removed lungs in the course of breath, and liquid products of disintegration – mainly kidneys and partially sweat glands. The excess of these substances breaks a homeostasis and therefore it is harmful to an organism.
Instruction
1. Carry lungs, skin and kidneys to eliminative organs. At the same time kidneys, mochetochnik, the bladder and an urethra which are carrying out urination play the main role. The main function of secretory bodies – maintenance of constancy of the internal environment.
2. Blood comes to kidneys on renal arteries. Here it is purified from excess substances and comes back in a blood-groove on renal veins. The hazardous substances filtered by kidneys form urine which on mochetochnik goes to a bladder. At the time of urination the circular muscle (sphincter) closing an exit in an urethra relaxes, walls of a bubble are reduced, urine is pushed out outside.
3. The kidney is a pair bean-shaped body. The concave part turned to a backbone is called kidney gate. The renal artery entering them bears the crude blood. There are kidney gate renal veins and a mochetochnik. On veins "pure" blood goes to the lower hollow vein of a big circle of blood circulation, and through a mochetochnik the released products of disintegration come to a bladder.
4. The kidney consists of external cortical and internal brain substance. The last is differentiated on the kidney pyramids adjoining the bases cortical substance, and tops sent to a kidney lokhanka. The kidney lokhanka represents the tank collecting urine to its exit in a mochetochnik.
5. Microscopic structurally functional unit of a kidney is nephron. In each kidney their about one million, and in them is filtered blood plasma. Nephron consists of the capsule passing into long wavy a tubule. Capsules and an initial part of tubules are located in cortical substance of a kidney, and their continuation – in brain substance.
6. Blood plasma a la carte gets through a thin wall of a blood vessel into a nephron capsule crack. Uniform elements (erythrocytes, leukocytes, platelets) and proteins remain in arteriola. Disintegration products, water and nutrients get into a tubule of nephron. Everything together they make primary urine. Per day about 150 l of primary urine are formed, and all blood (5 liters on average) passes through kidneys about 300 times.
7. Along a wavy tubule primary urine moves ahead further. There is the return absorption in blood of the necessary substances and the most part of water, and in the tubule there is "waste" unnecessary an organism. Secondary, final urine – the concentrated solution of urea and salts oxalic, uric, phosphoric and other acids is so formed. Follow wavy tubules collective, directing liquid to a kidney lokhanka. In day 1.5-2 liters of secondary urine are formed.