Food and oxygen are combined in the cells of the body to produce energy (catabolism). In the process, however, the substance of the food and oxygen is not destroyed. Instead, the small particles of which the food and oxygen are made are actually rearranged into new combinations. These are waste products. When foods like sugars and fats which contain particles of carbon, hydrogen, and oxygen combine with oxygen in cells, the wastes produced are gases called carbon dioxide (carbon and oxygen) and water (hydrogen and oxygen) in the form of vapor. These gases are removed from the body by exhalation through the lungs.
Protein foods are more complicated than sugars and fats. They contain carbon, hydrogen, and oxygen plus nitrogen and other elements. The waste that is produced when proteins combine with oxygen is called nitrogenous waste, and it is more difficult to excrete (to separate out) from the body than are gases like carbon dioxide and water vapor.
The body cannot efficiently put the nitrogenous waste into a gaseous form and exhale it, so it excretes it in the form of a soluble (dissolved in water) waste substance called urea. The major function of the urinary system is to remove urea from the bloodstream so that it does not accumulate in the body and become toxic.
Urea is formed in the liver from ammonia, which in turn is derived from the breakdown of simple proteins (amino acids) in the body cells. The urea is carried in the bloodstream to the kidneys, where it passes with water, salts, and acids out of the bloodstream and into the kidney tubules as urine. Urine then travels down the ureters into the bladder and out of the body.
Besides removing area from the blood, another important function of the kidneys is to maintain the proper balance of water, salts, and acids in the body fluids. The kidney does this by secreting some substances into the urine and holding back other necessary substances in the body.
Exercise 1.Match the following terms in a) with their meanings in b):
a) 1. essential hypertension; 2. hematuria; 3. pyelonephritis; 4. micturition;
5. renal ischemia; 6. specific gravity.
b) 1. condition of holding back blood from the cells of the kidney; 2. a determination of the amount of wastes, minerals, and solids in the urine; 3. high blood pressure in the kidney due to no apparent cause; 4. inflammation of a kidney; 5. blood in the urine; 6. urination.
Exercise 2.Translate into English:
Вуглекислий газ; нирки; канали; сечовина; сечовий міхур; необхідні речовини; сечовидільна система; розчинний; продукти виділення; частка; рідкі компоненти організму.