Anatomy of the Genitourinary System II: Bladder and Urethra

The lower urinary system comprises the bladder and urethra.

The bladder, a muscular and stretchable organ, is located behind the pubic bone.

In females, it is anterior to the vagina and uterus, while in males, it is superior to the prostate.

The primary function of the bladder is to store urine, typically between 400 to 500 milliliters.

It has four layers: the outer adventitia provides support, the detrusor muscle contracts to expel urine, the submucosa contains blood vessels and nerves, and the innermost urothelium prevents urine reabsorption.

At the base, the triangular trigone directs urine into the urethra.

Next, the urethra is a tube that carries urine from the bladder to the outside.

In females, it is about 2.5 to 5 centimeters, while in males, it extends 20 to 25 centimeters through the penis and is surrounded by the prostate.

Lastly, the flow of urine through the urethra is regulated by the involuntary internal urethral sphincter and the voluntary external urethral sphincter.