If the proteases such as pepsin and trypsin, digest protein, why don't they digest the stomach and small intestine, since the stomach and small intestine are both made from protein?
1 Answer
Jul 28, 2017
- Pepsin is secreted as pepsinogen in stomach and converted into active pepsin by HCl present in gastric juice. HCl and pepsin both could be corrosive on stomach lining: but to prevent that a thick layer of mucus keeps the stomach lining covered all the time.
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Stomach juice is secreted regularly during the meal time; hence if one skips a meal chances of damage to the stomach wall goes up. Action of pepsin on gut wall causes ulcer.
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Trypsin is secreted as inactive trypsinogen from pancreatic tissue. Once it reaches small intestine, it is converted in active trypsin by enterokinase enzyme.
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Trypsin acts in alkaline medium and it is prevented from taking any damaging action on intestinal lining of lumen due to presence of protective mucus layer on it.
