What is the primary function of the kidneys?

The primary function of the kidneys is to filter waste products from the blood and produce urine. This essential process helps to maintain homeostasis by regulating the body’s fluid balance, electrolyte levels, and acid-base balance. As blood flows through the kidneys, waste products and excess substances are removed, while necessary components are reabsorbed back into the bloodstream. This filtration process culminates in the formation of urine, which is then excreted from the body, thereby eliminating waste and toxins effectively.

Additionally, while the kidneys do play a role in hormone production, such as the regulation of blood pressure through the secretion of renin and the production of erythropoietin for red blood cell formation, these functions are secondary to their primary role in waste filtration. Other choices, such as regulating body temperature or storing bile, are functions performed by different organs in the body and are not related to the primary function of the kidneys.