How is blood cleared in the kidneys?

The body contains 4 to 6 liters of blood. It is constantly circulating and passing through the kidneys. The kidneys cleanse about 1500 liters of blood per day. Filtration takes place with the help of nephrons. There is water, salts and processed substances in the blood. Proteins and blood elements remain in it. The rest is excreted as primary urine. Then the tubular cells return water and salts to the blood. All that remains is the final urine. With the help of the kidneys, the water-salt balance is regulated and they affect the pressure.