The urinary system includes the kidneys, bladder and tubes and acts as the filtering mechanism for the blood. These organs control the amount of water and salts that are absorbed back into the blood and what is taken out as waste.
One of the major functions of the Urinary system is the process of excretion. Excretion is the process of eliminating, from an organism, waste products of metabolism and other materials that are of no use. The urinary system maintains an appropriate fluid volume by regulating the amount of water that is excreted in the urine. Other aspects of its function include regulating the concentrations of various electrolytes in the body fluids and maintaining normal pH of the blood.
The urinary system removes a type of waste called urea from the blood. Urea is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys.
Each kidney is made of numerous (about 1 million) called tubules known as nephrons, which are the functional unit of the kidneys. About 180 liters of blood, which run through these nephrons, are reduced to urine by the process of filtration, re-absorption and secretion by the nephrons.
Human beings on an average excrete about 1 to 1.5 liters of urine per day. The Human Biology site features a detailed info about the Urinary System.
