What wastes are removed by the excretory system?

The excretory system removes harmful or unnecessary substances to keep the body in chemical balance. The kidneys are the main players, filtering blood to remove urea, a byproduct of protein breakdown. They also eliminate creatinine (from muscle metabolism), uric acid (from nucleic acid breakdown), excess salts, and water. The lungs expel carbon dioxide and some water vapor, while the skin releases small amounts of salts and urea through sweat.

The liver contributes by detoxifying chemicals and converting harmful ammonia into urea before it reaches the kidneys. The intestines help by excreting solid waste through feces. Altogether, this system prevents the buildup of toxic materials that could poison cells or disrupt metabolism. For example, if urea or creatinine accumulate due to kidney malfunction, the body can experience fatigue, nausea, and confusion.

By continuously filtering and eliminating waste, the excretory system ensures the body maintains clean blood, stable fluid levels, and proper pH balance—vital for healthy organ function and overall well-being.