Normal kidneys. Coloured axial (horizontal) CT (computed tomography) scan through a human abdomen at the level of the kidneys. The front of the body is at top. The two kidneys (blue) lie either side of the spine (brown/white, lower centre). Part of the liver (green, upper left) and parts of the intestines (brown, upper right) are also seen. The kidneys filter the blood, removing and excreting nitrogenous waste materials as urine. The liver is a large organ that helps to detoxify the blood and also makes and stores important body chemicals. It also makes bile, a digestive fluid that is passed into the intestines, part of the digestive system.