Question

How is our gut lining protected from its own secretion of proteases?

Answer 1

Gut secretes mucus which inactivates the proteases and thereby protects the gut lining from their action. In addition, most of the proteases are secreted in their inactive form e.g: trypsin is secreted in its inactive form (trypsinogen), such that they do not act on the gut lining and this also helps protect the gut lining.