Question
Sat April 18, 2015 By: Vipul_p_doshi

how is following digested in the allimentary canal
 
1 Proteins
 
2 carbohaydrates
 
3 fats

Expert Reply
Hemangi Binny
Mon April 20, 2015

Digestion of proteins:

In stomach:
  • Pepsinogen is converted into pepsin.
  • Pepsin hydrolyses proteins into proteoses and peptones (peptides).
In small intestine:
  • Trypsin, chymotrypsin and carboxypeptidase present in the pancreatic juice act on the partially digested proteins from the stomach (proteins, peptones, proteoses) into dipeptides.
  • Dipeptidases (Enzymes present in the intestinal juice) act on dipeptides and break them down into amino acids.
Digestion of carbohydrates:

In buccal cavity:

  • Saliva secreted into the buccal cavity contains electrolytes such as Na+, K+, Cl-,  enzymes such as salivary amylase and lysozyme.
  • Hydrolytic action of salivary amylase hydrolyses the starch into maltose.

In small intestine:

  • Pancreatic amylase present in the pancreatic juice hydrolyses remaining carbohydrates into disaccharides.
  • Diasccharidases (enzymes present in the intestinal juice) such as maltase, sucrase, lactase breakdown disaccharides into monosaccharides such as glucose, maltose, fructose, etc.

Digestion of fats:

In stomach:

  • Gastric lipases are secreted in very small amount. They bring about mild hydrolysis of fats into fatty acids and glycerol.

In small intestine:

  • Bile breaks down large lipid molecules into small micelles of fats. This process is called emulsification. Emulsification makes the further digestion of fats by lipases easy.
  • Pancreatic lipases break down fat micelles into diglycerides first and then monoglycerides.
  • Intestinal lipases acts on monoglycerides and break them down into fatty acids and glycerol.
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