Which organ is primarily responsible for filtering blood in mammals?

The kidneys are the primary organs responsible for filtering blood in mammals. They play a crucial role in homeostasis by removing waste products, excess substances, and toxins from the bloodstream. As blood flows through the kidneys, it is filtered in structures called nephrons, which remove waste while retaining necessary components such as proteins and cells. The filtered waste is then excreted as urine, while important substances are reabsorbed back into the bloodstream. This filtration process is vital for regulating electrolyte balance, blood pressure, and fluid homeostasis, which are essential for maintaining overall health.

In contrast, the liver primarily processes nutrients, detoxifies harmful substances, and produces bile, while the heart is responsible for pumping blood throughout the body. The lungs are involved in gas exchange, primarily oxygenating the blood and removing carbon dioxide. Each of these organs has specific functions that are essential for bodily functions, but the filtration of blood is uniquely performed by the kidneys.