Which organ is primarily responsible for filtering blood in the human body?

The kidney is the organ primarily responsible for filtering blood in the human body. It plays a crucial role in the urinary system by removing waste products and excess substances from the bloodstream. As blood passes through the kidneys, they filter out toxins, urea, and other waste materials, which are then excreted as urine.

Moreover, the kidneys help maintain the body's fluid and electrolyte balance, regulate blood pressure, and produce hormones such as erythropoietin, which stimulates red blood cell production. This multifaceted functionality underscores their essential role in filtering blood and maintaining homeostasis in the body. Other organs mentioned do have important functions, but they do not perform the specific role of blood filtration in the same way the kidneys do.