The role of the urinary system in maintaining homeostasis is to regulate the composition of blood and remove waste products from the body. It primarily functions through the kidneys, which filter excess substances and toxins from the bloodstream, producing urine. This system balances fluid levels, electrolytes, and blood pH while controlling blood pressure through the regulation of water and solute excretion. By effectively managing these aspects, the urinary system plays a vital role in sustaining overall health and stability.