The liver helps maintain physiological homeostasis by regulating blood sugar and converting nitrogenous waste to a form that can be safely excreted, explains Wikipedia. The liver stores excess blood sugar and releases it back into the bloodstream when levels fall.
The liver replenishes its energy stores during the ingestion of energy-rich foods such as carbohydrates, explains Robert S. Sherwin of the American Diabetes Association. The energy stores are in the form of glycogen and triglycerides, notes Van Den Berghe G. in a report titled "The role of the liver in metabolic homeostasis: implications for inborn errors of metabolism," published on PubMed. Triglycerides are stored in the body's adipose tissue.
During fasting, such as the period between evening meals and breakfast, the liver breaks down glycogen and gluconeogenic amino acids sourced from muscle tissue into glucose that is then released into the bloodstream. Fasting also causes the liver to manufacture ketone bodies. These act as energy sources when glucose is unavailable, explains Wikipedia. Ketone bodies are produced from fatty acids and ketogenic amino acids, notes Berghe G. These processes are regulated by glucose, glucagon and insulin and help keep blood sugar levels constant.
The liver also plays a critical role in the excretion of nitrogenous waste from the human body, explains Elmhurst College. The liver metabolizes ammonia, an extremely toxic chemical derived from the breakdown of proteins, into a nitrogenous product called urea. Urea is then filtered out of the bloodstream by the kidneys.