What do kidneys do and why are they important?

You have two kidneys. Each kidney is about the size of your fist. They are located near the middle of your back, just below the rib cage. Healthy kidneys do many important jobs. For example, kidneys:
  • Remove waste products and extra water from your body
  • Help control blood pressure
  • Help make red blood cells
  • Help keep bones healthy
Think of your kidneys as a coffee filter. When you make coffee, the filter keeps the coffee grounds inside, but allows water to pass through. Your kidneys do something similar. They keep the things you need inside your body, but filter out things you don’t need.
Each of your kidneys has about 1.5 million filters called nephrons. Nephrons remove wastes and extra fluid from your blood in the form of urine. The urine flows through two tubes, called ureters, to the bladder. The urine is stored there until you go to the bathroom. The wastes come from the breakdown of what you eat or drink, medicine you take, plus normal muscle activity.