Role of Enzymes in GIT.pptx

Role of Enzymes in GIT.pptx

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  ROLE OF ENZYMESIN GASTRO INTESTINAL SYSTEM DR Shridhar Savadatti Associate Professor and HOD Department Of Kriya Shareeera Shri Shivayogeeshwara Rural Ayurvedic Medical College and Hospital, Inchal Belagavi
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  METABOLISM  Metabolism isa kind of chemical activity that happens between different types of cells. In this article, we will try to know about the role of enzymes in metabolism and how different metabolism enzymes work.  Metabolism is of two different kinds that include:  Anabolism: In this process, all molecules follow the synthesis process to make bigger molecules.  Catabolism: in the process of catabolism, the larger molecules break into smaller molecules.
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  MOUTH AND SALIVARYGLANDS
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  Salivary Amylase Salivary amylaseis a carbohydrate-digesting (amylolytic) enzyme. It acts on cooked or boiled starch and converts it into dextrin and maltose. Though starch digestion starts in the mouth, major part of it occurs in stomach because, food stays only for a short time in the mouth. Optimum pH necessary for the activation of salivary amylase is 6. Salivary amylase cannot act on cellulose. Maltase Maltase is present only in traces in human saliva and it converts maltose into glucose. Lingual Lipase Lingual lipase is a lipid-digesting (lipolytic) enzyme. It is secreted from serous glands situated on the posterior aspect of tongue. It digests milk fats (pre-emulsified fats). It hydrolyzes triglycerides into fatty acids and diacylglycerol
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  Stomach
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  Gastric juice actsmainly on proteins. Proteolytic enzymes of the gastric juice are pepsin and rennin. Pepsin Pepsin is secreted as inactive pepsinogen. Pepsinogen is converted into pepsin by hydrochloric acid. Optimum pH for activation of pepsinogen is below 6. Action of pepsin Pepsin converts proteins into proteoses, peptones and polypeptides. Pepsin also causes curdling and digestion f milk (casein). Gastric Lipase Gastric lipase is a weak lipolytic enzyme when compared to pancreatic lipase. It is active only when the pH is between 4 and 5 and becomes inactive at a pH below 2.5. Gastric lipase is a tributyrase and it hydrolyzes tributyrin (butter fat) into fatty acids and glycerol's.
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  Actions of OtherEnzymes of Gastric Juice. 1. Gelatinase: Degrades type I and type V gelatin and type IV and V collagen (which are proteoglycans in meat) into peptides. 2. Urase: Acts on urea and produces ammonia 3. Gastric amylase: Degrades starch (but its action is insignificant) 4. Rennin: Curdles milk (present in animals only).
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  Pancreas
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  i. Digestion ofproteins: Trypsin is the most powerful proteolytic enzyme. i. It is an endopeptidase and breaks the interior bonds of the protein molecules and converts proteins into proteoses and polypeptides ii. Curdling of milk: It converts caseinogen in the milk into casein iii. Blood clotting: It accelerates blood clotting iv. It activates the other enzymes of pancreatic juice, viz. a. Chymotrypsinogen into chymotrypsin b. Procarboxypeptidases into carboxypeptidases c. Proelastase into elastase d. Procolipase into colipase v. Trypsin also activates collagenase, phospholipase A and phospholipase B vi. Autocatalytic action: Once formed, trypsin itself converts trypsinogen into trypsin.
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  Actions of chymotrypsin Digestion of proteins: Chymotrypsin is also an endopeptidase and it converts proteins into polypeptides  Digestion of milk: Chymotrypsin digests caseinogen faster than trypsin. Combination of both enzymes causes rapid digestion of milk. Carboxypeptidases  Carboxypeptidases are carboxypeptidase A and carboxypeptidase B.  Carboxypeptidases are exopeptidases and break the terminal bond of protein molecules. Exopeptidases split the polypeptides and other proteins into amino acids.
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  Nucleases Nucleases of pancreaticjuice are ribonuclease and deoxyribonuclease, which are responsible for the digestion of nucleic acids. These enzymes convert the ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) into mononucleotides. Elastase Elastase is secreted as inactive proelastase, which is activated into elastase by trypsin. Elastase digests the elastic fibres. Collagenase Collagenase is secreted as inactive pro collagenase, which is activated into collagenase by trypsin. It digests collagen.
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  DIGESTION OF LIPIDSby Pancreatic Juice Pancreatic lipase  Pancreatic lipase is a powerful lipolytic enzyme. It digests triglycerides into monoglycerides and fatty acids. Activity of pancreatic lipase is accelerated in the presence of bile.  Digestion of fat by pancreatic lipase requires two more factors: A. Bile salts, which are responsible for the emulsification of fat, prior to their digestion B. Colipase, which is a coenzyme necessary for the pancreatic lipase to digest the dietary lipids.  About 80% of the fat is digested by pancreatic lipase. Deficiency or absence of this enzyme leads to excretion of undigested fat in feces (steatorrhea)
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  DIGESTION OF CARBOHYDRATES Pancreaticamylase is the amylolytic enzyme present in pancreatic juice. Like salivary amylase, the pancreatic amylase also converts starch into dextrin and maltose.
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  Small Intestine
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  Secretion from smallintestine is called succus entericus. Enzymes of succus entericus act on the partially digested food and convert them into final digestive products. Enzymes are produced and released into succus entericus by enterocytes of the villi. Proteolytic Enzymes Proteolytic enzymes present in succus entericus are the peptidases, these peptidases convert peptides into amino acids.
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  Amylolytic Enzymes Lactase, sucraseand maltase convert the disaccharides (lactose, sucrose and maltose) into two molecules of monosaccharides Dextrinase converts dextrin, maltose and maltriose into glucose. Trehalase or trehalose glucohydrolase causes hydrolysis of trehalose (carbohydrate present in mushrooms and yeast) and converts it into glucose. Lipolytic Enzyme Intestinal lipase acts on triglycerides and converts them into fatty acids.
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  Reference  Section 4– Digestive System – Text book Essential Of Medical Physiology by K Sembulingam and Prema Sembulingam
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  Thank you