urinäärikanali

The urinäärikanali, also known as the urethra, is a tube that connects the bladder to the outside of the body. Its primary function is to expel urine from the body during urination. In males, the urethra is longer and also serves as a passageway for semen during ejaculation. In females, it is much shorter and located anterior to the vagina.

The lining of the urethra is composed of mucous membrane, which helps to protect it from infection and irritation. Smooth muscle in the wall of the urethra allows for controlled expulsion of urine. At the opening to the outside of the body, the urethra is surrounded by sphincter muscles that help to control the flow of urine and prevent leakage.

The length of the male urethra is approximately 20 centimeters, passing through the prostate gland and the penis. The female urethra is about 3-4 centimeters long and opens just above the vaginal opening. Due to its shorter length, females are more susceptible to urinary tract infections (UTIs) as bacteria can more easily travel from the external environment to the bladder.

The process of urination, or micturition, is a complex reflex involving the nervous system. When the bladder fills with urine, stretch receptors send signals to the brain, triggering the urge to urinate. Voluntary control over the external sphincter allows individuals to delay urination until an appropriate time and place.