Which pair of organs filters waste from the blood to produce urine?

The pair of organs that filters waste from the blood to produce urine is the kidneys. Located behind the abdominal cavity, the two bean-shaped organs continuously process blood and help keep the body’s internal chemistry balanced.

Each kidney contains roughly one million nephrons, its microscopic filtering units. In a nephron, blood pressure drives water and small dissolved substances through the glomerulus, while blood cells and most large proteins remain in the bloodstream. The tubules then reabsorb useful materials such as glucose, amino acids, sodium, and much of the water, while secreting additional unwanted substances.

The resulting urine contains metabolic wastes such as urea and uric acid, along with excess water and electrolytes. It travels from each kidney through a ureter to the urinary bladder. The liver also processes toxins and produces waste, but it does not form urine; the spleen filters blood cells, and the lungs remove carbon dioxide.

The kidneys have several other jobs, including regulating blood pressure, maintaining acid-base balance, controlling fluid levels, activating vitamin D, and producing hormones such as erythropoietin.