Other than the primary excretory organs we have more organs to mention. The first one is skin that is known as sweat and oil glands that are found in our skin. The second one is the lungs that are excreted by two kinds of gaseous substances known as water vapour and carbon dioxide. This is the excretion of a few substances such as onion, garlic or other such species within whom vapour component is available to be excreted via lungs. The last one is the liver. Cells of the liver play a key role in the excretion process with the help of the conversion of more ammonia and ammonia acids of blood within the urea.