The kidneys are organs located on either side of the spine, at the
small of the back. Kidneys filter the blood and help balance water, salt, and
mineral levels in the blood. They also produce hormones that help regulate
blood pressure and blood supply.
Waste from the kidneys is carried out of the body in urine. Urine
flows through tubes (ureters) to the bladder, where it is stored until a person
is ready to urinate. The waste and urine then leave the bladder to exit the
body through a tube called the urethra.