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 are converted to glucose in an attempt to support energy production.
Suppose excessive fat metabolism occurs in conjunction with inadequate carbohydrate metabolism. In that case, there are inadequate amounts of metabolites to react with acetyl CoA, leading to excess levels of acetyl CoA. The increased levels of acetyl CoA produce 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 insulin release into the bloodstream from the pancreatic beta cells. The released insulin in the bloodstream 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 decrease overnight or because of a lack of food ingestion or heavy exercise, the pancreatic alpha cells begin releasing glucagon into the bloodstream. Glucagon signals the liver and muscle tissue to degrade or break down 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).
