Urinary bladder,urethra

Urinary Bladder

The urinary bladder is a hollow, muscular, expandable organ collecting urine. The bladder sits on the pelvic floor and is held in place by ligaments attached to other organs and the pelvic bones. The bladder stores urine until nerves from the bladder send a message to the brain that the bladder is full and the urge to empty the bladder intensifies. When you urinate, the brain signals the bladder muscles to tighten, squeezing urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax. As these muscles relax, urine exits the bladder through the urethra.

Urethra

The urethra is a tube connecting the urinary bladder to the outside of the body. In the male, the urethra is the conduit for fluid waste and semen. It is shaped like an S to follow the line of the penis. The portion of the urethra passing through the prostate gland is known as the prostatic urethra. The prostatic portion of the urethra passes along the neck of the urinary bladder (vesical or bladder neck) and through the prostate gland. This section of the urethra is designed to accept the drainage from the tiny ducts within the prostate and is equipped with two ejaculatory tubes. The female urethra is straight, approximately 4 cm long, and leads out of the body via the urethral orifice and has no reproductive function. Due to the location of the prostate in males relative to the urethra, male patients with prostate issues tend to exhibit urinary dysfunction.

At the time of urination, the bladder muscles will tighten and squeeze urine from the bladder into the urethra. The urethra is the outlet for urine to exit the body. The proximal opening of the urethra is called the bladder neck. In men, it is adjacent to the prostate gland. If the bladder neck does not open appropriately or completely during voiding, the bladder neck may become obstructed. This can be caused in men by an enlarged prostate. In women, vaginal or pelvic prolapse is the most common cause of bladder neck obstruction.