Question

All of these are true of villi except?

A. they contain lacteals of the lymphatic system
B. They propel chyme through the pyloric sphincter
C. They line the interior wall of the small intestine
D. They help absorb nutrients from ingested food

Answer 1

Villi are small, finger-like projections lining the small intestine that increase the surface area for the absorption of nutrients, whereas mechanical digestion involves the physical breakdown of food which villi do not participate.

Step-by-step explanation:

The statement about villi that is not true is that they aid in the mechanical digestion of food particles. The primary function of villi and microvilli in the small intestine is to increase the surface area for nutrient absorption. These structures provide an expansive area across which nutrients can diffuse from the digested food into the bloodstream or lymphatic system.

Villi are lined with absorptive cells that have even smaller projections called microvilli, which further enhance their capacity to absorb nutrients. While it is true that damaged villi can lead to impaired nutrient absorption, they are not directly involved in the mechanical digestion of food; that process primarily involves the physical breakdown of food by the teeth and the churning motions of the stomach and intestines.

In summary, villi and microvilli play a crucial role in facilitating the absorption of nutrients, not in mechanical digestion. It is through these specialized structures that the small intestine is able to effectively extract and transport necessary nutrients throughout the body.