adding on to brenna's post

Everyone has blood and you can't expect that your blood to use everything that's in it. Your blood needs to balance the amount of things you need just like a scale. Well when it balances the scale it has to have things leftover. That's where the kidneys come in. The kidneys have 1 million tiny filter called nephrons that are so tiny yo have to look through a really strong microscope to see them. The blood runs through the kidney and the nephrons go to work cleaning the blood. Once the blood is filtered it leaves the kidney and the waste gets mixed with water. The kidneys filter blood 400 times a day! Your kidneys are about the size of a computer mouse!