Which organ filters metabolic waste from the blood?

The kidney is the organ responsible for filtering metabolic waste from the blood. It plays a crucial role in maintaining homeostasis by regulating the body’s fluid balance, electrolyte levels, and acid-base balance. The kidneys filter out waste products, such as urea and creatinine, which are byproducts of protein metabolism and muscle metabolism, respectively. Once filtered, these waste products are excreted from the body in urine.

Additionally, the kidneys also reabsorb useful substances, such as glucose and certain ions, back into the bloodstream, ensuring that the body retains essential nutrients while eliminating unnecessary waste. This process occurs through millions of functional units called nephrons, which perform the filtration and reabsorption tasks.

In contrast, the other organs listed do not have this filtering function. The stomach is primarily involved in the digestion of food, absorbing nutrients rather than filtering blood. The small intestine also absorbs nutrients from digested food, rather than actively filtering waste. While the liver is involved in detoxifying substances and metabolizing drugs, it does not perform the direct filtration of blood like the kidneys do. The liver processes many nutrients and produces waste that eventually gets filtered by the kidneys, but the initial filtration responsibility lies with the kidneys.