The human kidneys are located against the back muscles in the upper abdominal cavity with one on either side of the spine. The right kidney typically sits lower than the left kidney to accommodate the liver, and both kidneys are connected to the bladder through thin tubes called ureters.
The main function of each kidney is to filter waste products from the blood, such as urea, excess salts and other toxins. As they do this, the kidneys create urine, which travels down the ureters and into the bladder. Kidneys also help regulate blood pressure, help in the creation of red blood cells and help keep bones healthy.