Which statement about small intestine protection against autodigestion is NOT accurate?

• A. Mucous barrier protects mucosa
• B. Tight junctions prevent leakage
• C. Rapid epithelial turnover
• D. Enzymes are secreted in active form

Answer: (D)

The key idea here is how the small intestine guards itself from its own digestive enzymes. To prevent autodigestion, the system relies on several protective features that work together: a sturdy mucous barrier that lines and protects the mucosa, tight junctions between epithelial cells that seal the lining and stop leakage, and very rapid turnover of the epithelial lining so damaged cells are quickly shed and renewed. In addition, digestive enzymes are not released in their active form. They are secreted as inactive precursors, or zymogens, so they won’t start digesting the tissue where they’re produced. Activation happens later, in the intestinal lumen, by specific enzymes such as enterokinase activating trypsinogen to trypsin, which then can activate other enzymes. This controlled activation keeps powerful enzymes away from the mucosa until they’re safely in the lumen, helping to prevent self-digestion.