The main organ involved in the filtration of blood is the kidneys. These bean-shaped organs play a crucial role in maintaining the body's homeostasis by filtering waste products, excess substances, and toxins from the bloodstream. The kidneys help regulate fluid balance, electrolyte levels, and blood pressure through the formation of urine. They contain millions of tiny filtering units called nephrons, which perform the filtration process. Proper kidney function is essential for overall health, as impaired kidneys can lead to a buildup of harmful substances in the body and various health complications.