Two types of pancreatic nuclease are responsible for their digestion: deoxyribonuclease, which digests DNA, and ribonuclease, which digests RNA. The nucleic acids DNA and RNA are found in most of the foods you eat. The fatty acids include both short-chain (less than 10 to 12 carbons) and long-chain fatty acids.
#DIGESTED PROTEINS FREE#
Pancreatic lipase breaks down each triglyceride into two free fatty acids and a monoglyceride. However, because the pancreas is the only consequential source of lipase, virtually all lipid digestion occurs in the small intestine.
The three lipases responsible for lipid digestion are lingual lipase, gastric lipase, and pancreatic lipase. Small amounts of dietary cholesterol and phospholipids are also consumed. The most common dietary lipids are triglycerides, which are made up of a glycerol molecule bound to three fatty acid chains. Lipid DigestionĪ healthy diet limits lipid intake to 35 percent of total calorie intake. Proteins are successively broken down into their amino acid components. Insufficient lactase can lead to lactose intolerance.įigure 4. Sucrase splits sucrose into one molecule of fructose and one molecule of glucose maltase breaks down maltose and maltotriose into two and three glucose molecules, respectively and lactase breaks down lactose into one molecule of glucose and one molecule of galactose. Three brush border enzymes hydrolyze sucrose, lactose, and maltose into monosaccharides. After amylases break down starch into smaller fragments, the brush border enzyme α-dextrinase starts working on α-dextrin, breaking off one glucose unit at a time. In the small intestine, pancreatic amylase does the ‘heavy lifting’ for starch and carbohydrate digestion (Figure 2). The chemical digestion of starches begins in the mouth and has been reviewed above. While indigestible polysaccharides do not provide any nutritional value, they do provide dietary fiber, which helps propel food through the alimentary canal. Your bodies do not produce enzymes that can break down most fibrous polysaccharides, such as cellulose. Your digestive system is also able to break down the disaccharide sucrose (regular table sugar: glucose + fructose), lactose (milk sugar: glucose + galactose), and maltose (grain sugar: glucose + glucose), and the polysaccharides glycogen and starch (chains of monosaccharides). Glucose, galactose, and fructose are the three monosaccharides that are commonly consumed and are readily absorbed. The average American diet is about 50 percent carbohydrates, which may be classified according to the number of monomers they contain of simple sugars (monosaccharides and disaccharides) and/or complex sugars (polysaccharides). *These enzymes have been activated by other substances. Triglycerides that have been emulsified by bile salts Α-Dextrins, disaccharides (maltose), trisaccharides (maltotriose) Deoxyribonuclease: deoxyribonucleic acids.Aminopeptidase: amino acids and peptidesĪmino acids at the carboxyl end of peptides.Aminopeptidase: amino acids at the amino end of peptides.Phosphates, nitrogenous bases, and pentoses The Digestive Enzymesįree fatty acids, and mono- and diglycerides The many enzymes involved in chemical digestion are summarized in Table 1. This is accomplished by enzymes through hydrolysis. Large food molecules (for example, proteins, lipids, nucleic acids, and starches) must be broken down into subunits that are small enough to be absorbed by the lining of the alimentary canal. Most absorption occurs in the small intestine. Digestion begins in the mouth and continues as food travels through the small intestine.
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