Excretion is the process of removal metabolic waste product from the body cells of living organisms. The different chemical activities in the body produce many by-products several of which are wastes. These waste products if allowed to accumulate will turn out to be toxic and affect the physiological activities of the body.
The human body also has five different way of excreting unwanted waste product. These include the skin, lungs, liver, gut and the kidney. The skins is used to excrete sweat which is a solution of water, ions and urea, the lungs excrete carbon dioxide and water through the process of respiration.
The liver is used as an excretion source for bile, which contains mineral ions, bile pigments and cholesterol, the gut excretes mucus cells, water and bile waste. Last but not the least the kidney is used to excrete urine, which is a solution of urea, mineral ions, water, and other unwanted chemicals in the body.