Various Types of Urinary Tract Structures

Description: The kidney is a bean shaped organ made of intricate webs of blood vessels and drainage canals for filtering wastes from the blood. Humans have two kidneys, but can function with just one in the absence of disease. Kidneys are cushioned in the human abdomen by fatty tissue called peri-nephric fat, which also protects the adrenal gland which is on top of the kidney. Waste filtered out by the kidney drains into the bladder as urine.

Description: The ureters are muscular tubes, or ducts, that carry liquid waste, or urine, from the kidneys to the bladder. Each kidney drains into a single ureter in humans. Backflow of urine is prevented by valves in the duct and pressure in the bladder.

Description: The urinary bladder is a sterile muscular sac, covered with transitional epithelium, where urine collects after filtration in the kidneys. The bladder is present in the pelvic region and swells like a balloon as it fills. An adult human bladder can hold 200-400 mL of urine before putting pressure on the sphincter to open for release. The most the bladder can hold is usually less than 800 mL. Urination is promoted by the detrusor muscle, the muscle layer of the bladder, which squeezes the fluid out.

Description: The urethra is a tube, or duct, that carries urine from the urinary bladder to be expelled out of the body. It travels through the shaft of the penis in men and through the clitoris in women. The urethra is shorter in women, making them more susceptible to urinary tract infections. There are often commensal bacteria that populate outside the external urethra sphincter.