Digestive system (Carbohydrate, Protein, fat)
36 likes•21,008 views
The document explains the digestion processes of carbohydrates, proteins, and fats, highlighting the role of hydrolysis and specific enzymes in each stage of digestion. Carbohydrate digestion begins in the mouth and continues in the duodenum and small intestine, while protein digestion primarily occurs in the stomach and small intestine. Fat digestion is notably facilitated by pancreatic lipase and bile salts in the small intestine, emphasizing the importance of emulsification in increasing fat surface area for enzyme action.
Digestive system (Carbohydrate, Protein, fat)
- 1. DIGESTION Carbohydrates, Proteins, Fats Md. Saiful Islam Dept. of Pharmaceutical Sciences North South University Facebook Group: Pharmacy Universe YouTube Channel: Pharmacy Universe
- 2. The chemistry of digestion is simple because, in the case of all three major types of food (carbohydrates, proteins and fats), the same basic process of hydrolysis is involved. The only difference lies in the types of enzymes required to promote the hydrolysis reactions for each type of food. Hydrolysis is a reaction involving the breaking of a bond in a molecule using water.
- 3. DIGESTION OF CARBOHYDRATE • Only three major sources of carbohydrates exist in the normal human diet. They are sucrose, which is the disaccharide known popularly as cane sugar; lactose, which is a disaccharide found in milk; and starches, which are large polysaccharides present in almost all non-animal foods, particularly in potatoes and the different types of grains. • The diet also contains a large amount of cellulose, which is a carbohydrate. However, no enzymes capable of hydrolyzing cellulose are secreted in the human digestive tract. • The digestions of carbohydrate in different parts of digestive system occur as follows: • In the mouth: We take carbohydrate in the form of disaccharide and polysaccharide. No change of disaccharide occurs in the mouth cavity but only boiled starch is digested by the salivary amylase (ptyalin) into maltose. • In the stomach: In the acid media, the function of ptyalin is lost. So no change of carbohydrate occurs in the stomach. HCl hydrolyze some sucrose only.
- 4. • In the duodenum: The acidity is neutralized by the help of local hormone secretin and facilitates the action of pancreatic amylase and converts all form of starch into maltose. Starch → Maltose • In the Intestine: The carbohydrate splitting enzyme of small intestine (maltase, lactase, and sucrose) digest all the disaccharide in the following way: maltase • Maltose Glucose + Glucose lactase • Lactose Glucose + Galactose sucrase • Sucrose Glucose + Fructose
- 5. • The digestion of protein in different parts of digestive system occurs as follows: • In the mouth: No digestion of protein in the mouth. • In the stomach: In presence of pepsin and gastric HCl, protein is converted into peptone. Pepsin • Protein Peptone HCl DIGESTION OF PROTEIN
- 6. • In the duodenum: Here trypsin and chymotrypsin of pancreatic juice act on broken and unbroken peptone and converts it into polypeptide. Chymotrypsin • Protein/peptone Polypeptide. Trypsin • In the small intestine: Here the intestinal juice mainly the erepsin (proteolytic enzyme) hydrolyzes the peptone and converts the polypeptide into end products of protein digestion i.e. amino acid. This amino acid is absorbed in the gut by active and passive process. • So the protein digestion occurs in the following form: Protein → peptone → Polypeptide → Amino acid
- 7. DIGESTION OF FAT • We take fat in the form of neutral fat (triglyceride). The digestion of fat in different parts of the digestive system occurs as follows: • In the mouth: No digestion of fat occurs in the mouth cavity. • In the stomach: Fat digestion may occur in the stomach because the fat splitting enzyme (gastric lipase) is present in the gastric juice but this enzyme is inactive in the acid media.
- 8. • In the small intestine: the main digestion of fat occurs in the small intestine by pancreatic lipase with the help of bile salts. • The first step in fat digestion is physically to break the fat globules into very small sizes so that the water-soluble digestive enzymes can act on the globule surfaces. This process is called emulsification of the fat. • Most of the emulsification occurs in the duodenum under the influence of bile. However, bile does contain a large quantity of bile salts as well as the phospholipid lecithin. Both of these, but especially the lecithin, are extremely important for emulsification of the fat. • The polar parts (the points where ionization occurs in water) of the bile salts and lecithin molecules are highly soluble in water, whereas most of the remaining portions of their molecules are highly soluble in fat. • Therefore, the fat-soluble portions of these liver secretions dissolve in the surface layer of the fat globules, with the polar portions projecting.
- 9. The polar projections, in turn, are soluble in the surrounding watery fluids, which greatly decreases the interfacial tension of the fat and makes it soluble as well. A major function of the bile salts and lecithin, especially the lecithin, in the bile is to make the fat globules readily fragmentable by agitation with the water in the small bowel. Each time the diameters of the fat globules are significantly decreased as a result of agitation in the small intestine, the total surface area of the fat increases manyfold. Because the average diameter of the fat particles in the intestine after emulsification has occurred is less than 1 micrometer, this represents an increase of as much as 1000-fold in total surface areas of the fats caused by the emulsification process.
- 10. • The lipase enzymes are water-soluble compounds and can attack the fat globules only on their surfaces and splits into free fatty acids and monoglycerides. Bile+agitation pancreatic lipase Fat Emulsified fat Monoglycerides & fatty acids • Fats are digested in the following way: Triglyceride → Diglyceride + Fatty acid Diglyceride → Monoglyceride + Fatty acid Monoglyceride → Glycerol + Fatty acid
- 11. THANK YOU