Anatomy and Physiology II Practice Test

Which organ is primarily responsible for filtering blood and removing waste products?

1. Liver

2. Kidneys

3. Spleen

4. Gallbladder

The correct answer is: Kidneys

The kidneys are primarily responsible for filtering blood and removing waste products. They play a crucial role in the body's excretory system, maintaining homeostasis by regulating water and electrolyte balance, and removing waste products through the formation of urine. As blood passes through the kidneys, nephrons— the functional units of the kidneys—filter out excess ions, urea, and water. This filtration process separates important substances the body needs from waste products that should be expelled. Following filtration, the kidneys reabsorb necessary substances back into the bloodstream, ensuring that essential nutrients and particles are not lost. The liver, while it plays an important role in metabolic processes and detoxification, particularly processes substances like drugs and alcohol, primarily functions in processing nutrients and does not filter blood in the same way as the kidneys. The spleen is involved in filtering blood but focuses on the removal of old or damaged blood cells, and the gallbladder stores bile but does not participate in waste filtration. Hence, the kidneys are uniquely positioned as the primary organs for filtering blood and removing waste products effectively.