Chapter 3 - Carbohydrate Metabolism and Its Diseases

Abstract

This chapter focuses on the biochemical mechanisms underlying diseases associated with carbohydrate metabolism. The major function of ingested carbohydrates is to serve as energy sources. Carbohydrates are also precursors of essential intermediates for use in synthetic processes. The digestion of carbohydrates in animals begins with the initial contact of the carbohydrates in their food with the enzymes of salivary juice. Starch of plant foods and glycogen of meat are split into their constituent monosaccharides by the action of amylase and maltase. This activity ceases as the food matter passes into the stomach, where the enzymatic action is destroyed by hydrochloric acid. Within the stomach, only a small portion of the ingested carbohydrate is hydrolyzed before passing into the small intestine. In the small intestine, digestion of carbohydrates takes place quickly by the carbohydrate-splitting enzymes contained in the pancreatic juice and in the succus entericus. This chapter begins with a discussion on digestion, absorption, and metabolism of absorbed carbohydrates. The chapter also elaborates concepts related to insulin and carbohydrate metabolism. The subject of blood glucose and its regulation is also explained. The chapter concludes with presenting an overview of the disorders of carbohydrate metabolism and disorders of ruminants associated with hypoglycemia.