The liver has 4 main functions. In detoxification, toxins (poisonous chemicals produced by living cells or organisms) are broken down, often by enzymes found in the liver, for example catalase which breaks down hydrogen peroxide, a product of metabolism. The liver is also responsible for the breakdown of excess amino acids to form keto acids and ammonia, which is then processed in the ornithine cycle to produce urea as a waste product. (Here the whiteboard would be used to produce a diagram of the ornithine cycle and to answer any questions)Another role involves the breakdown of red blood cells by kupffer cells found in the sinusoids of the liver, a process that produces bile pigments. The final role is the metabolism of carbohydrates. This involves the synthesis of glycogen in glycogenesis, and the formation of glucose by the processes of glycogenolysis and gluconeogenesis. (Whiteboard used to draw structure of liver)