What is the primary function of the renal system?

The primary function of the renal system, also known as the urinary system, is to filter impurities from the blood. This process is essential for maintaining homeostasis within the body. The kidneys, which are the main organs of the renal system, perform this filtration by removing waste products, excess electrolytes, and toxins from the bloodstream, which are then excreted as urine. Additionally, the renal system plays a crucial role in regulating fluid balance, blood pressure, and the acid-base balance of the body.

While the production of hormones is an aspect of the renal system—specifically, the kidneys produce hormones like erythropoietin and renin—the primary and most significant role is still the filtration of blood. Digesting food is a function associated with the digestive system, and regulating body temperature is primarily managed by the integumentary and nervous systems. Thus, the answer highlighting the filtering of impurities accurately reflects the most central role of the renal system.