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

The primary function of the kidneys is to eliminate water and waste products from the body. They play a crucial role in the urinary system by filtering the blood to remove excess substances, including urea, creatinine, and various toxins. This process not only helps in maintaining the body's fluid and electrolyte balance but also ensures that harmful waste does not accumulate in the bloodstream.

The kidneys work through a complex system of nephrons, where blood is filtered, and the necessary substances are reabsorbed while waste and excess water are excreted as urine. This filtering mechanism is vital for regulating homeostasis in the body, as it ensures proper levels of hydration and balances electrolytes such as sodium and potassium.

While the kidneys do also produce hormones and contribute to blood pressure regulation and red blood cell production, these functions are secondary to their primary role of waste elimination. Regulating body temperature is primarily the function of other systems, such as the integumentary system. Therefore, eliminating water and waste products is the fundamental function of the kidneys, emphasizing their importance in maintaining overall health and homeostasis.