Editing Glycogen (section)

===Liver===
As a meal containing [[carbohydrate]]s or protein is eaten and [[digestion|digested]], [[blood glucose]] levels rise, and the [[pancreas]] secretes [[insulin]]. Blood glucose from the [[portal vein]] enters liver cells ([[hepatocyte]]s). Insulin acts on the hepatocytes to stimulate the action of several [[enzyme]]s, including [[glycogen synthase]]. Glucose molecules are added to the chains of glycogen as long as both insulin and glucose remain plentiful. In this [[postprandial]] or "fed" state, the liver takes in more glucose from the blood than it releases.

After a meal has been digested and glucose levels begin to fall, insulin secretion is reduced, and glycogen synthesis stops. When it is needed for [[Food energy|energy]], glycogen is broken down and converted again to glucose. [[Glycogen phosphorylase]] is the primary enzyme of glycogen breakdown. For the next 8–12 hours, glucose derived from liver glycogen is the primary source of blood glucose used by the rest of the body for fuel.

[[Glucagon]], another hormone produced by the pancreas, in 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).