What metabolic waste is primarily voided by the urinary system?

The urinary system is primarily responsible for the excretion of metabolic waste in the form of urine. Urine is produced by the kidneys as they filter blood, removing excess substances, toxins, and waste products resulting from metabolic activities. The composition of urine includes urea, creatinine, uric acid, and various ions, which are by-products of protein metabolism and other cellular processes.

While blood plasma is part of the bodily fluid that is filtered by the kidneys, it is not directly voided. Instead, it is processed to form urine. Interstitial fluid and lymphatic fluid also play roles in the body's fluid balance and immune response but are not metabolic wastes eliminated through the urinary system. Therefore, urine is distinctly the primary method through which the body expels metabolic waste, making it the correct choice in this context.