Which organ is primarily responsible for filtering waste from the blood?

The kidneys are primarily responsible for filtering waste from the blood. They play a crucial role in the body's excretory system by removing toxins, excess salts, and urea, which is a byproduct of protein metabolism, from the bloodstream. This filtration process occurs in the nephrons, the functional units of the kidneys, where blood is filtered, and necessary substances like water, electrolytes, and nutrients are reabsorbed while waste products are excreted as urine.

The kidneys also help regulate blood pressure, maintain the body’s acid-base balance, and control electrolyte levels, illustrating their multifaceted role in homeostasis. This highlights their importance not only in waste removal but also in overall metabolic health.