Discuss the main steps in the digestion of proteins as the food passes through different parts of the alimentary canal.

(N/A) The digestion of proteins begins in the stomach and is completed in the small intestine.
The enzymes that act on proteins are known as proteases.
Digestion in the stomach:
The gastric glands in the stomach wall secrete gastric juice, which contains $HCl$, pepsinogen, and rennin. The acidic medium converts inactive pepsinogen into active pepsin. Active pepsin converts proteins into proteases and peptides.
$Proteins \xrightarrow{Pepsin} Proteases + Peptides$
Rennin is involved in the coagulation of milk proteins.
Digestion in the small intestine:
In the small intestine, pancreatic juice and intestinal juice act on the food.
Action of pancreatic juice:
Pancreatic juice contains inactive enzymes: trypsinogen, chymotrypsinogen, and procarboxypeptidases. Enterokinase, secreted by the intestinal mucosa, activates trypsinogen into trypsin.
$Trypsinogen \xrightarrow{Enterokinase} Trypsin + \text{Inactive peptide}$
Activated trypsin then activates chymotrypsinogen into chymotrypsin and procarboxypeptidases into carboxypeptidases.
$Proteins \xrightarrow{Chymotrypsin} Peptides$
$Peptides \xrightarrow{Carboxypeptidase} \text{Smaller peptide chains} + \text{Amino acids}$
Action of intestinal juice:
Intestinal juice (succus entericus) contains dipeptidases that complete the digestion of proteins.
$Dipeptides \xrightarrow{Dipeptidases} \text{Amino acids}$