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urethra(yo͝orē`thrə), canal in most mammals that carries urine from the bladderbladder, urinary,
muscular sac located in the pelvis that stores urine and contracts to expel it from the body. Urine enters the bladder from the kidneys through the ureters and is discharged from the body via the urethra. The bladder of the adult human can hold over a pint (0.
..... Click the link for more information. to the outside of the body; in the male it also serves as a genital duct. The urethra is about 1 1-2 in. long (3.8 cm) in women, terminating above the vaginal opening. In men the urethra is about 8 in. (20 cm) long and terminates in an opening at the end of the penis. In the male the urethra is connected to the prostate glandprostate gland,
gland that is part of the male reproductive system. It is an organ about the size of a chestnut and consists of glandular and muscular tissue. It is situated below the neck of the bladder, encircling the urethra.
..... Click the link for more information. and to the seminal vesicles and testes. It transports semen received from those organs as well as urine. See also urinary systemurinary system,
group of organs of the body concerned with excretion of urine, that is, water and the waste products of metabolism. In humans, the kidneys are two small organs situated near the vertebral column at the small of the back, the left lying somewhat higher than the
..... Click the link for more information. .
the terminal section of the urinary tract in some invertebrates, in all vertebrates, and in man. The urethra is a tube whose wall consists of an internal mucous membrane, a muscular membrane, and a connective tissue membrane.
In males the urethra emerges from the urinary bladder, descends through the prostate gland, passes between the two layers of the urogenital diaphragm under the pubic arch, enters the corpus spongiosum of the penis, and opens to the exterior of the body at the tip of the penis. The male urethra is about 20 cm long and about 7 mm in diameter. In females the urethra is much shorter—about 5 cm—and follows an almost straight path that ends in an external opening in the vestibule of the vagina. The section of the urethra that emerges from the urinary bladder is surrounded by a sphincter—a ring-shaped constrictor muscle.
The walls of the empty urethra are normally touching, becoming distended only during urination. In males the orifices of the deferent ducts and of the prostate gland open into the urethra at the point where the urethra passes through the prostate; thus, both urine and semen are expelled through the male urethra. The mucous membrane of the urethra contains glands. Inflammatory processes in the urethra can result in constriction caused by scarring, a condition that requires surgical treatment.