Kidneys Simplified
Kidneys are organs we all have. They act as biological filters, getting rid of excess "stuff" we don't need in our blood. Humans have two kidneys, located on either side of the spine below the ribcage. Although they are each only about 12 cm long, together, they are able to filter half a cup, or about 118 mL of blood every minute. They get rid of acid, extra water, and unneeded minerals in our blood. You may be wondering where the filtered waste goes. Well, that waste ends up becoming our urine.
Put simply, kidneys are fist sized filters.