Trivia: What is the urinary system’s primary function?
Filtering the blood
Producing white blood cells
Defending against pathogens
Absorbing nutrients
Correct Answer: Filtering the blood
So why is this answer correct? : The urinary system filters blood, creating waste (urine) as a byproduct. This system also balances the levels of certain substances (such as potassium, water, and sodium) in the body. Organs in this system include the kidneys, ureters, bladder, urethra, and sphincter.