Urethra

A tube responsible for the passage of urine and, in males, semen out of the body.

The urethra is a narrow tube that conducts urine from the bladder to the outside of the body. In males, it also serves as a passage for semen during ejaculation. This dual function makes the urethra an essential component of both the urinary and reproductive systems.

Terminologia Anatomica

urethra

System

Urinary system

Function

The primary function of the urethra is to facilitate the excretion of urine, thereby playing a critical role in the body’s waste management system. Urine is formed in the kidneys, transported to the bladder by the ureters, and stored until voluntary contraction of the bladder muscles signals the need to urinate. The urethra is equipped with an internal and external sphincter, which help control the flow of urine. In males, during sexual arousal, the urethra also becomes a conduit for semen. This dual use is vital for reproductive function, allowing for the timely expulsion of sperm into the female reproductive tract. The urethra's mucosal lining produces mucus that helps protect it and facilitates the smooth passage of both urine and semen.

Location

In females, the urethra is relatively short, measuring approximately 4 centimeters in length, and is positioned directly above the vaginal opening, entering the body just below the pubic symphysis. This leads to a straight path to the exterior, making it easier for urine to exit. In males, the urethra is significantly longer, measuring about 18 to 20 centimeters, and passes through the penis, making it more complex in structure. It consists of several segments: the prostatic urethra (passing through the prostate gland), the membranous urethra (located between the prostate and the penis), and the spongy (or penile) urethra, which runs through the penis itself. This longer route allows the urethra to serve not only as a urine passage but also as a conduit for semen during ejaculation.

Did You Know?

The male urethra performs a dual function, both as a urinary and reproductive tract.
In females, the shorter urethra increases the likelihood of urinary tract infections.
Urethral sphincters provide voluntary control over urination, making it possible to hold urine until a suitable time.
Some animals have adapted their urethra’s structure and function for different reproductive strategies.