Question

Why is the inner wall of alimentary canal not digested although the digestive enzyme can digest all the materials that make cells?

Answer 1

Mucus:

1. The mucus is a substance secreted along the walls of the alimentary canal.
   
2. Mucus helps food to slide through the canal without causing damage to the lining.
   
3. It also acts as a protective covering which keeps the digestive juices away from the walls of the alimentary canal.
   
4. The digestive juices can digest the internal cellular structures of the body and due to the barrier caused by the mucus it is not able to reach the cells and only digests the food.
   
5. This is why the inner walls of the alimentary canal are not digested.