Biological Systems MCAT Practice Exam

Which component of the urinary system is responsible for storing urine?

1. Kidney

2. Ureter

3. Urinary bladder

4. Urethra

The correct answer is: Urinary bladder

The urinary bladder is the component of the urinary system responsible for storing urine. It is a muscular sac located in the pelvis and can expand and contract to hold varying amounts of urine, typically up to 500 mL in adults. As urine is produced by the kidneys, it flows down the ureters into the bladder, where it is temporarily held until the body is ready to release it. When the bladder fills, stretch receptors signal the nervous system, prompting the urge to urinate. During urination, the bladder contracts, and urine is expelled through the urethra, which is the tube that leads to the outside of the body. In contrast, the kidneys are responsible for filtering blood to produce urine, the ureters transport urine from the kidneys to the bladder, and the urethra serves primarily as a conduit for urine to exit the body, but does not have a storage function. Thus, the urinary bladder's role in temporarily holding urine make it the correct answer.