The circulatory system also serves to remove waste products from the body. Certain wastes such as excess water, urea, uric acid and carbon dioxide are transported from the liver to the kidneys, where the blood is filtered. The urea is produced in liver and released into the bloodstream. It is then transported to the kidneys by blood to be excreted out in urine. These waste products are exchanged through diffusion as blood is being filtered by kidneys.
