Glycogen
Glycogen is a branched polysaccharide used as a readily available storage of glucose largely found in liver and muscle cells. It consists of a chain of alpha glucose molecules joined together mostly by 1-4 glycosidic bonds but 1-6 clycosidic linkages are also present approximately every 10 glucose residues, these linkages form the 'branches'.[1]
The glycogen store in muscle is released for muscle cells, whereas the glycogen released by liver cells is released for other cells. Glycogen is broken and used when cells require more ATP than they can produce from the bloodstream [2].