Dictionary

URI Upper respiratory infection. Infection of the air passages of the nose, the throat, and/or bronchial tubes.

urethroscope A device for examining the inside of the urethra.

urethritis Inflammation of the urethra, the tube that leads from the bladder to the outside of the body. Urethritis can have a number of causes, including irritation and sexually transmitted diseases such as chlamydia. Urethritis is closely associated with bacterial infection of the bladder (cystitis).

urethral sphincter A muscular mechanism that controls the retention and release of urine from the bladder. There are two urethral sphincters: the internal and external urinary sphincters. Part of the muscular bladder wall acts as the internal urethral sphincter and prevents urine from leaving the bladder to enter the urethra. This sphincter cannot be willfully…

urethra The tube that leads from the bladder and transports and discharges urine outside the body. In males, the urethra travels through the penis and carries semen as well as urine. In females, the urethra is shorter than in the male, and it emerges above the vaginal opening.

ureter One of the two tubes that carry urine from the kidneys to the bladder. Each ureter arises from a kidney, descends, and ends in the bladder.

uremia The presence of an excessive amount of urea in the blood. Uremia may be a sign of kidney disease or even kidney failure. See also urea.

urea breath test A procedure for diagnosing the presence or absence of the bacterium Helicobacter pylori in the upper gastrointestinal tract, which causes ulcers. Abbreviated UBT. UBT may be used to demonstrate that H. pylori has been eliminated by treatment with antibiotics. UBT is based on the ability of H. pylori to break down urea,…

urea 1 A substance that contains nitrogen and is normally cleared from the blood by the kidney and excreted via the urine. Diseases that compromise the function of the kidney often lead to increased blood levels of urea, which can be measured by the blood urea nitrogen (BUN) test. See also uremia. 2 A synthetic…

urate A salt that is derived from uric acid. When the body cannot metabolize uric acid properly, urates can build up in body tissues or crystallize within joints. See also gout; uric acid.

uracil One of the nucleotide bases in RNA. Uracil takes the place in RNA that thymine occupies in DNA. Abbreviated U.

urachus A canal that connects the urinary bladder to the umbilicus (bellybutton) during fetal development. The urachus is normally obliterated, so it is usually a solid cord. Failure for the urachus to fill in leaves it open. The telltale sign of an open urachus is leakage of urine through the umbilicus. An open urachus is…