The main organ responsible for filtering blood in the human body is the kidneys. Located on either side of the spine, these two bean-shaped organs play a crucial role in maintaining homeostasis by regulating the body's fluid balance, electrolytes, and waste removal. Blood enters the kidneys through the renal arteries, where it is filtered through nephrons, the functional units of the kidneys. The nephrons remove waste products and excess substances, which are excreted as urine. Additionally, the kidneys help regulate blood pressure and produce hormones, such as erythropoietin, that stimulate red blood cell production.