Kidney anatomy, illustration. The kidneys filter waste from the blood and excrete it as urine. The ureters (cream) carry the urine to the bladder. Blood is carried to the kidneys by the renal arteries (red) and away from them by the renal veins (blue). Each kidney can be divided into four anterior segments (left) and three posterior segments. The anterior segments are the superior, or apical segment (purple), the anterior superior segment (yellow), the anterior inferior segment (red) and the inferior segment (green). The posterior segments are the superior, or apical segment (purple), the posterior segment (orange) and the inferior segment (green).