The human organ responsible for filtering blood is the kidneys. The kidneys are a pair of bean-shaped organs located on either side of the spine, just below the rib cage. They play a critical role in maintaining homeostasis by filtering waste products, excess substances, and toxins from the blood, which are then excreted as urine. Additionally, the kidneys help regulate blood pressure, electrolyte balance, and the body's acid-base balance. They also produce hormones such as erythropoietin, which stimulates the production of red blood cells. Proper kidney function is essential for overall health.