Urinary system. Coloured intravenous urogram (IVU) Xray image of the abdominal region of a person showing a normal urinary tract. The kidneys are seen (purple, top left and right) with the two ureters leading down to the bladder (yellow, bottom centre). In the background the bones of lower spine and pelvic girdle are seen. The urinary tract produces and disposes of urine. Urine is produced in the kidneys and channeled down to the bladder from where it is expelled via the urethra. IVU images are produced by injecting the patient with an iodinebased radioopaque contrast medium prior to Xray.