When cells in the body break down proteins into forms they can utilize, they produce ammonia wastes that the liver turns into urea (a chemical compound of carbon, hydrogen, nitrogen, and oxygen). When cells break down carbohydrates, they produce water and carbon dioxide as waste products. If these useless waste products were allowed to accumulate in the body, they would become dangerous to the body's health. The body eliminates these wastes (and solid wastes, also) in a process known as excretion. The body system most responsible for waste excretion is the urinary system, which eliminates water, urea, and other waste products from the body in the form of urine. Because of this main function, it is often referred to as the excretory system.

Design: Parts of the Urinary System

The main organs of the urinary system are the kidneys, which form urine. The other...