Proper regulation of carbohydrate metabolism
Normally, over 80% of the energy produced by the body is derived from the combustion of carbohydrates. When carbohydrate metabolism is severely limited, the cells begin to oxidize fat reserves for energy. Also, proteins are degraded to amino acids which in turn are converted to glucose in an attempt to support energy production. If excessive fat metabolism occurs in conjunction with inadequate carbohydrate metabolism, there are inadequate amounts of metabolites to react with acetyl CoA, in turn leading to excess levels of acetyl CoA. The increased levels of acetyl CoA produces a build up of ketone bodies, leading to ketosis. Since ketone bodies are also acids, this leads to a condition known as acidosis. Severe acidosis, if not counteracted, can result in coma and death.
The roles of insulin and glucagon in normal blood glucose regulation
In a healthy individual, blood glucose concentrations are maintained within a normal range through the processes of glycogenolysis, glycolysis, glycogenesis, and gluconeogenesis. The regulation of blood glucose levels is mainly under the control of the pancreatic hormones, insulin and glucagon. After a meal, blood glucose levels rise and trigger the release of insulin into the blood stream from the pancreatic beta cells. The released insulin into the blood steam enables glucose to be absorbed into the liver and muscle tissue and stores the excess glucose in the form of glycogen (glycogenesis). When blood glucose levels begin decreasing overnight or because of a lack of food ingestion or due to heavy exercise, the pancreatic alpha cells begin releasing glucagon into the blood stream. Glucagon signals the liver and muscle tissue to degrade or breakdown the stored glycogen into glucose which then enters the bloodstream and raises blood glucose levels (glycogenolysis). As the body needs more glucose, glucagon stimulates the liver to produce more glucose from amino acids (gluconeogenesis).