The organ in the human body responsible for filtering blood is the kidneys. The kidneys are two bean-shaped organs located in the lower back, and they play a crucial role in maintaining the body's internal balance. They filter waste products, excess substances, and toxins from the blood, producing urine for excretion. Additionally, the kidneys help regulate electrolyte levels, blood pressure, and red blood cell production. They also play a role in maintaining the body's pH balance. Due to their essential functions, kidney health is vital to overall well-being, and kidney disease can have serious health implications.