Year 10 triple science pupils have demonstrated their fine dissecting skills on lamp kidneys. The pupils were so interested in seeing them in real life as opposed to a book! Kidneys are organs of excretion, their structure and their arrangement of tissues are vital for their function. The primary function of the kidneys is the elimination of excess water and wastes from the bloodstream by the production of the liquid waste known as urine . The main structural and functional units of the kidneys are tiny structures called nephrons.