Glycogen many respects serves as a countersignal to insulin. In response to insulin levels being below normal (when blood levels of glucose begin to fall below the normal range), glucagon is secreted in increasing amounts and stimulates both glycogenolysis (the breakdown of glycogen) and gluconeogenesis (the production of glucose from other sources). Muscle cell glycogen appears to function as an immediate reserve source of available glucose for muscle cells. Other cells that contain small amounts use it locally, as well. As muscle cells lack glucose-6-phosphatase, which is required to pass glucose into the blood, the glycogen they store is available solely
Glucose paradox small absorption of glucose. After the body's digestion of carbohydrates and the entering the circulatory system in the form of glucose, some will be absorbed directly into the muscle tissue and will be converted into lactic acid throughout the anaerobic energy system, rather than going directly to the liver and being converted into glycogen. The lactic acid is then taken and converted by the liver, forming the material for liver glycogen. The majority of the body's liver glycogen is produced indirectly, rather than directly from glucose in the blood. Under normal physiological conditions, glucose is a poor precursor compound and