Digestion and Absorption – Solutions
1. Answer briefly:
a. Why are villi present in the intestine and not in the stomach?
b.How does pepsinogen change into its active form?
c.What are the basic layers of the wall of alimentary canal?
d.How doe bile help in the digestion of fats?
a. The villi are finger-like projections present in the mucosal wall of the small intestine. They increase the surface area for more efficient absorption of food. These villi are provided with numerous blood vessels that absorb the digested products of proteins and carbohydrates, carrying them to the blood stream.
The villi also contain lymph vessels for absorbing the products of fat-digestion. In the stomach, the mucosal wall forms irregular folds, known as rugae.
The villi, if present in the stomach, would not serve any purpose as the digestion of food in the stomach is partial..