To better understand urinary retention, it helps to understand the anatomy of the bladder and genitourinary system.

In an adult, the bladder can hold 10 to 20 ounces of urine--about as much liquid as in one can of soda. Urine is carried out of the body through the urethra, a tube at the bottom of the bladder.

As the bladder fills, it pushes against the rest of the organs in the abdomen. Urine empties from the bladder through the urethra. Muscles located in the base of the urethra control the flow of urine. During urination, these muscles relax, and urine is allowed to pass.

Anatomy examples:

• Genitourinary system
• Bladder and lower urinary tract in women
• Bladder and lower urinary tract in men