Which organ is primarily involved in filtering waste from the blood?

• A. Liver
• B. Heart
• C. Kidneys
• D. Spleen

Answer: (C)

The kidneys play a critical role in filtering waste from the blood. They are part of the urinary system, specifically designed to remove waste products and excess substances to maintain homeostasis in the body. Blood enters the kidneys through the renal arteries, where it is filtered in units called nephrons. The nephrons remove toxins, urea, and excess ions from the blood, which are then excreted as urine. This process not only eliminates waste but also helps regulate electrolyte balance, blood pressure, and fluid balance.

In contrast, the liver is primarily responsible for metabolizing nutrients and producing bile, not for filtering waste from the blood in the same way the kidneys do. The heart's primary function is to pump blood throughout the body and maintain circulation, while the spleen focuses on filtering blood related to immune response and recycling iron from hemoglobin, but it does not filter waste from the blood like the kidneys. Therefore, the kidneys are uniquely specialized for waste filtration and play an essential role in the body's overall homeostasis.