Page 13 - LN-CH-16

increases the surface area of fat available for digestion by the lipase (as bile also
activates lipases).
Enzymes from Intestine
Intestinal mucosal epithelium has goblet cells (secretes mucus). Thus, the
secretions of the brush border cells of mucosa together with the goblet cell
secretions forms the intestinal juice (also known as succus entericus).
The succus entericus thus, contains various enzymes
(a) Disaccharidases, e.g., Maltase for digestion of maltose into glucose.
(b) Dipeptidases
(c) Lipases
(d) Nucleosidases
Pancreatic and intestinal lipases together helps in the emulsification of fats.
The mucus along with the bicarbonates from the pancreas helps in protecting the
mucosal layer of intestine from the action of acid and also provides an alkaline
medium (pH-7.8) for enzymatic activities.
Glands (Brunner’s gland) from sub-mucosal layer of intestine also helps in this.
Hence, all the enzymes in the succus entericus acts on the end products of the
above mentioned reactions in order to form their respective simpler forms.

All these final steps takes place very close to mucosal epithelial cells of the
intestine.
All the biomacromolecules mentioned above breakdown in the duodenum region of
small intestine, while the simpler forms are absorbed in the other two regions of
small intestine, i.e., jejunum and ileum.
Digestion in Large Intestine
The last stage of chemical simplification of food occurs in the last part of the
alimentary canal, i.e., large intestine. This is carried out by bacterial action. Glands of
this region tends to secrete mucus, i.e., enzymes are not secreted into this part of
the digestive system.
The undigested and the unabsorbed substances are finally passed on to the large
intestine.
Note:
* There are more than 500 species of bacteria found in the colon region of the large
intestine which are not usually harmful as long as they remain in the large intestine.