This Presentation deals with role of enzymes in gastro intestinal system

1. ROLE OF ENZYMES IN GASTRO INTESTINAL SYSTEM
DR Shridhar Savadatti
Associate Professor and HOD
Department Of Kriya Shareeera
Shri Shivayogeeshwara Rural Ayurvedic Medical College
and Hospital, Inchal
Belagavi

4. METABOLISM
 Metabolism is a 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.

5. MOUTH AND SALIVARY GLANDS

6. Salivary Amylase
Salivary amylase is 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

7. Stomach

8. Gastric juice acts mainly 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.

9. Actions of Other Enzymes 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).

10. Pancreas

11. i. Digestion of proteins: 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.

12. 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.

13. Nucleases
Nucleases of pancreatic juice 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.

14. DIGESTION OF LIPIDS by 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)

15. DIGESTION OF CARBOHYDRATES
Pancreatic amylase is the amylolytic enzyme present in pancreatic
juice. Like salivary amylase, the pancreatic amylase also converts
starch into dextrin and maltose.

16. Small Intestine

17. Secretion from small intestine 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.

18. Amylolytic Enzymes
Lactase, sucrase and 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.

19. Reference
 Section 4 – Digestive System – Text book Essential Of Medical Physiology by K
Sembulingam and Prema Sembulingam

20. Thank you