Briefly outline the role of the liver in glucose metabolism.
Liver cells carryout many different metabolic pathways and employ a good number of enzymes that are alternatively turned on or off depending on blood glucose levels. For example Excess glucose entering the blood after a meal is rapidly taken up by the liver and being converted to glycogen(glycogenesis) and stored there. Later, when blood concentrations of glucose begin to decline, the liver activates other pathways which lead to the conversion of glycogen to glucose (glycogenolysis) and export of glucose back into the blood for transport to all other tissues.
When liver glycogen reserves are exhaused, as occurs when an animal has not eaten for several hours/days, The liver cells recognize the problem and activate additional groups of enzymes that begin synthesizing glucose out of other molecules like amino acids and non-hexose carbohydrates (gluconeogenesis). This later thing is useful/very much essential in animals with non-carbohydrate diets.