Question

Why are villi present in the intestine and not in the stomach?

Answer 1

Hint: They increase the surface area for the absorption of various nutrients and water and occurs in the small intestine.

Complete step-by-step solution:
1. Villi are the small, finger-like projections that extend into the lumen of the small intestine. The villi was approximately 0.5-1.6 mm in length. These villi consist of many small projections from its epithelium; these projections are called microvilli. The villi increase the surface area of the intestinal walls for absorption.
2. The large surface area is required for absorption because the digestive nutrients like amino acids are transported through the process of diffusion via a semipermeable membrane. This decreases the distance, which has to be traveled by the digestive nutrients molecules. These villi are connected to the blood vessels, which helps the supply of nutrients to various body parts.
3. The epithelium of the villi in the small intestine consists of two main cells which are enterocytes and goblet cells. On the surface of the epithelium, enzymes for digestion are also present. They help in absorption due to the presence of thin-wall for shorter and effective diffusion along with efficient absorption of fatty acids and glycerol into the bloodstream. The inflammation in the villi causes coeliac diseases.

          The lumen of the small intestine

Note: The stomach collects the food through the esophagus and adds gastric acid and enzymes in it for the digestion of food. The stomach does not absorb any nutrients, absorption of nutrients occurs only in the intestinal region. It is only the region where substances are mixed together. Thus, the stomach does not require a large surface area and villi for nutrients absorption.