URINE every day.Around 1 litre of blood flows through the kidneys per minute.Kidneys also produce hormones that regulate VARIOUS bodily functions.Renin is ONE such hormone that regulates blood pressure.The basic, functional unit of kidneys are called nephrons and they help in filtering blood.The kidneys are made up of MILLIONS of nephrons.Kidney stone is a condition where minerals present in the urine clump or become crystalize, growing large enough to block the flow of urine.The average human kidney is no bigger than a closed fist and weighs just under 0.4kgs.Scientists have estimated that the number of nephrons present in the kidneys starts falling at 1% per year.Once kidney disease sets in, it cannot be REVERSED, its effects can only be slowed down.