Which of the following is a function of the urinary system?

• A. Regulating blood pressure
• B. Urine formation
• C. Digestion of nutrients
• D. Oxygen transport

Answer: (B)

The urinary system’s main job is to remove waste from the blood and maintain fluid and electrolyte balance by producing urine. The kidneys do this through urine formation, which involves filtering the blood, reabsorbing what the body still needs, and secreting waste into urine to be excreted. This direct action—creating and eliminating urine—is the primary function of the urinary system.

While regulating blood pressure can be influenced by the kidneys (through fluid balance and hormonal signals), and digestion and oxygen transport are handled by other systems (digestive and circulatory/respiratory, respectively), urine formation is the function that most directly defines the urinary system.