Digestion is the process of conversion of complex substances into simple absorbable forms. The human digestive system comprises the gastrointestinal tract or alimentary canal and associated glands such as the liver pancreas. Digestion occurs by both mechanical and chemical processes. Food gets mixed with various enzymes in the different parts of the digestive tract, which cause the breakdown of carbohydrates, proteins, fats present in the food.
Digestion of food starts in the mouth itself. Salivary amylase secreted by salivary glands is the first enzyme to mix with the food in the mouth. Salivary amylase catalyses the hydrolysis of starch into maltose, a disaccharide. The optimum pH for its activity is 6.8.
Salivary glands are one of the associated glands present in the buccal cavity. There are mainly three pairs of salivary glands, which produce saliva. They are parotid, submaxillary or submandibular and sublingual. Saliva contains electrolytes, salivary amylase and lysozyme. About 30% of starch present in the food is hydrolysed by salivary amylase. Lysozyme kills bacteria and prevents infection.
Further down in the digestive tract, the carbohydrate present in the chyme is acted on by pancreatic amylase, which converts polysaccharides to disaccharides. Succus entericus, the intestinal juice also contains carbohydrate digesting enzymes such as maltase, which converts maltose (disaccharide) to glucose, sucrase, which converts sucrose to glucose and fructose, etc.
Explore more: Digestive Enzymes
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