The main function of Carbohydrates is to provide energy but they also play an important role in: The construction of the body organs and Nerve cells The definition of persons physiological identity such as their blood group 1. Energy source and storage Starch and sugars are the main energy-providing carbohydrate sources and supply 4 kilocalories per gram. Simple sugars are absorbed directly by the small intestine into the bloodstream, where they are, then, transport to their place of use. Disaccharides are broken down by the digestive enzyme into simple sugars. The body also needs the help of digestive enzymes to break down the long chains of starches into their constituent sugars, which are then absorbed into the bloodstream. The human body uses carbohydrates in the form of glucose. Glucose can also be converted to glycogen, a polysaccharide similar to starch, which is stored in the liver and the muscles and is a readily available source of energy for the body. Th...