What is the primary function of the kidneys in the human body?

The primary function of the kidneys is to filter blood and remove waste products. This vital role involves the kidneys processing the blood to eliminate harmful substances, such as urea and creatinine, which are byproducts of metabolism. The kidneys also regulate the balance of electrolytes and fluids in the body, maintaining homeostasis, which is essential for overall health.

Their filtering process takes place in millions of tiny structures called nephrons, where blood is filtered, and essential substances are reabsorbed into the bloodstream while waste products are excreted in urine. This function is crucial not only for waste removal but also for regulating blood pressure, electrolyte balance, and acid-base homeostasis.

While the kidneys do participate in the production of hormones that regulate metabolism, that is not their primary function. Similarly, while they play a role in the storage and management of water and electrolytes, the core of their role revolves around filtering blood. Assisting in digestion is not a role associated with the kidneys, as that function is primarily managed by the gastrointestinal system. This clarifies why filtering blood and removing waste products is recognized as the kidneys' main function.