Narrator: A doctor speaks with a patient in his office.
Patient: So what do the kidneys do?
Doctor: Well, you have two kidneys and they're each about the size of your fist and they're located on each side of your spine. The kidneys are usually described simply as filters but they do a lot more than that. Their job really is to maintain the composition of the blood at a constant level. They do filter the blood and they remove waste products and water and they produce urine, which is waste products and water.
But in addition to that, they have many other functions. They play a major role in controlling blood pressure, they maintain a major role in preventing you from becoming anemic, and they also have a very important role in maintaining the strength of your bones.