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

The mucus is a substance secreted along the tube by cells lining its walls .Mucus helps food to slide through the canal without doing too much damage to the lining. It also forms a protective covering which keeps the digestive juices, which are inside the lumen of the canal, from coming into contact with the living cells of the walls. So the inner wall of alimentary canal is not digested.

Answer 2

the inner wall of alimentary canal is not digested because it has the following protective mechanism:

the gastric mucin secreted by the gastric mucosa act as a buffer which reduces high gastric acidity and prevents injury to inner wall of alimentary canal .

the enzymes are secreted only when food is present in the alimentary canal and they are in an inactive form.