 Have you ever wondered how a bite of cereal can be converted to energy for your body to use? These foods are carbohydrates, and they begin digestion in the mouth. Carbohydrates are foods rich in sugars. These sugars are called saccharides. Carbohydrates are many sugars linked together, such as cellulose, starch, and glycogen. Dysaccharides are two sugars linked together, such as sucrose, maltose, and lactose. Monosaccharides are single sugars, such as glucose, fructose, and lactose. Most foods have complex polysaccharides and need special tools and enzymes to break them into smaller disaccharides and monosaccharides. The enzymes break bonds, releasing energy. This process begins in the mouth with the enzyme salivary amylase secreted from the cirrus cells of these salivary glands, peritid, submandibular, and buccal. The food that was broken down in the mouth by being chewed into smaller pieces and mixed with salivary amylase and other salivary juices will now be swallowed and passed through the esophagus to the stomach. No chemical carbohydrate digestion happens here because the actions of salivary amylase are stopped by the acid secretions in the stomach. Now those chains of polysaccharides will split into disaccharides. The mixture, known as chyme, once it enters the stomach, now enters the beginning portion of the small intestine, the duodenum. It is here that pancreatic amylase is released from the pancreas in response to the presence of carbohydrates in the chyme. This will continue the breakdown of carbohydrates to disaccharides. Again, you may be thinking, hmm, how did the pancreas know that there were carbohydrates in the chyme of the duodenum? The presence of the chyme entering the small intestine activates the anterior endocrine cells to release CCK, cholecysticlinin, and that hormone tells the acinar cells of the pancreas to release pancreatic amylase. There are also brushed border enzymes in the mucosa of the small intestine, including lactase, maltase, and sucrase. These enzymes complete the breakdown of disaccharides to monosaccharides. Do you know the disaccharides that the enzymes lactase, maltase, and sucrase will work on? Lactose, sucrose, and maltose. Carbohydrate digestion in action. Carbohydrates begin digestion in the mouth, travel through the esophagus and stomach, and then travel to the duodenum, where they will be chemically digested further. The pancreas secretes enzymes to break the polysaccharides into disaccharides. The liver absorbs the monosaccharides. The monosaccharides can now be used for energy. The cells use breakdown products for energy to build new cell parts, or to build products to be used by that cell, or exported out of that cell for use elsewhere or for muscle contraction. Congratulations! You have completed this learning activity, Carbohydrate Digestion.