What is the primary function of the kidneys?

The primary function of the kidneys is to filter waste products and excess substances from the blood. This process is crucial for maintaining homeostasis in the body. The kidneys perform several essential functions, including the regulation of electrolyte balance, the maintenance of acid-base balance, and the removal of urea, creatinine, and other metabolic waste products from the bloodstream. As blood passes through the kidneys, nephrons—functional units of the kidneys—filter out these waste products, which are then excreted as urine. Additionally, the kidneys play a vital role in regulating blood pressure and producing essential hormones, like erythropoietin, which stimulates red blood cell production. However, their primary and most critical function remains the filtration and excretion of waste products, reinforcing their importance in overall health and bodily functions.