What is the primary function of the urinary system?

• A. Control digestion
• B. Regulate blood pressure
• C. Remove waste products of metabolism from the blood by excreting them in the urine
• D. Produce hormones

Answer: (C)

The urinary system’s main job is to remove waste products from metabolism by excreting them in urine. The kidneys filter the blood, forming urine that contains wastes such as urea, creatinine, and uric acid, along with excess water and electrolytes. Through filtration, reabsorption, and secretion in the nephrons, the body eliminates these wastes while preserving essential substances, helping maintain fluid balance, electrolyte levels, and acid-base balance. The system also supports regulating blood pressure via the renin-angiotensin-aldosterone system and can produce hormones like erythropoietin, and activate vitamin D, but these are secondary to the primary task of waste removal.