<P> Excretion is the process by which metabolic waste is eliminated from an organism . In vertebrates this is primarily carried out by the lungs , kidneys and skin . This is in contrast with secretion , where the substance may have specific tasks after leaving the cell . Excretion is an essential process in all forms of life . For example , in mammals urine is expelled through the urethra , which is part of the excretory system . In unicellular organisms , waste products are discharged directly through the surface of the cell . </P>
<P> Excretion is the process by which metabolic waste is eliminated from an organism . In vertebrates this is primarily carried out by the lungs , kidneys and skin . This is in contrast with secretion , where the substance may have specific tasks after leaving the cell . Excretion is an essential process in all forms of life . For example , in mammals urine is expelled through the urethra , which is part of the excretory system . In unicellular organisms , waste products are discharged directly through the surface of the cell . </P>
removal of excretory products from the human body
removal of excretory products from the human body
Excretion
Excretion