||The Excretory System removes waste that collects in the body during metabolism. Metabolism is when the bady takes in air, food and liquid. The body uses most of these things to grow and make energy, but the body can’t use all of it. The leftovers are called waste. These waste products can be toxic if they are not eliminated. Major organs of the excretory system include the kidneys, liver, bladder, lungs and large intestine. Yes, even the lungs – when you exhale, the lungs eliminate gases your body can’t use.