The urethra is the passageway between the bladder and the external part of the body, which allows urine to be excreted from the body.
The urethra is a thin, fibromuscular tube that begins at the lower opening of the bladder and extends through the pelvic and urogenital diaphragms to the outside of the body, called the external urethral orifice. The urethra also connects the to the ductus deferens in males, for the ejaculation of sperm. There is a sphincter at the upper end of the urethra, which serves to close the passage and keep the urine inside the bladder.
As the passage needs to traverse the length of the penis, it is significantly longer in males than females. It is approximately 4 cm in length for females, whereas it is about 20 cm in the male body.
The male urethra consists of three parts:
The physiological function of the ureter is to allow the passage of urine to outside the body for excretion. When the receptors in the bladder sense that it is full, a response pathway occurs to allow the sphincter to open and the urine to pass into the urethra. This process involves both voluntary and involuntary controls, which allows individuals to dictate when they urinate unless the bladder becomes overfilled when it may occur spontaneously.
The urethra serves an additional purpose in men, as it is also utilized as a passageway for semen when a man ejaculates. Similarly, this involves a complex pathway that releases the semen from the ductus deferens for ejaculation.
As mentioned previously, there are several differences in the urethra between men and women. These include:
In some circumstances, the urethra may be affected by certain factors that cause abnormalities in the area. Complications that involve the urethra that may occur include: