What is the main purpose of the urinary system?

The main purpose of the urinary system is waste elimination. The urinary system plays a crucial role in filtering out waste products and excess substances from the bloodstream, which are then excreted from the body through urine. This process is vital for maintaining homeostasis, as it regulates the body's fluid balance, electrolytes, and pH levels by removing metabolic wastes, toxins, and other substances that the body no longer needs.

While the other functions mentioned, such as gas exchange, metabolic regulation, and hormonal regulation, are important in their own rights, they do not encapsulate the primary role of the urinary system. Gas exchange pertains primarily to the respiratory system, while metabolic regulation involves various processes throughout the body to maintain energy balance. Hormonal regulation does occur within the urinary system, notably through the kidneys producing hormones like erythropoietin and renin, but these functions support the primary goal of waste elimination rather than defining it.