Medical doctors who specialize in the problems of the urinary tract, including urine problems, prostate conditions, impotence, and incontinence: "Urologists are experts for the bodily organs that produce, store, and discharge urine (liquid wastes produced by the kidneys that are the two bean-shaped excretory organs that filter wastes; especially, urea from the blood and excrete them and water in the form of urine. Such parts of the body include the kidneys, ureters (two tubes that convey urine from the kidneys to the urinary bladder), bladder (bag where urine collects before being passed from the body), and urethra (the duct through which urine is discharged)."