The urethra is a tube responsible for allowing urine to leave the body as it empties from the bladder. In men, semen also leaves the body through the urethra.
Because of the differences between male and female genitals, the urethra is slightly different in each gender. The female urethra is much shorter than its male counterpart. The opening is between the clitoris and the vagina in a woman. Infection is more common in a female urethra than a male urethra. Viral and bacterial infections tend to cause urethritis, which is marked by inflammation and painful urination.
Once a man's bladder is full, the urethra carries urine to the penis and out the meatus, which is located at the tip of the penis. The male urethra also carries semen and sperm out of the body during sexual acts. The male urethra is much longer than that of the female. The tube is not solely responsible for moving urine and semen, however. The urethral sphincter controls voluntary and involuntary urination. Those muscles include the internal and external sphincter muscles of the urethra. The male urethra is made of four main parts: the preprostatic urethra, the prostatic urethra, the membranous urethra and the spongy urethra.