Question

Describe how the extensive folding of the small intestine contributes to the process of digestion.

A) The undulating folds created by the muscularis mucosa do not allow undigested food to pass, to give more time for chemical digestion.
B) It greatly increases the surface area of the intestine, which aids in digestion and absorption.
C) It decreases the surface area of the digestive tract, which conserves resources and energy.
D) It traps digestive enzymes, keeping them only in areas where they are needed.

Answer 1

The extensive folding of the small intestine, including circular folds, villi, and microvilli, enhances the surface area significantly, which aids in efficient digestion and absorption of nutrients.

Step-by-step explanation:

The extensive folding of the small intestine plays a crucial role in digestion and absorption. The structure of the small intestine includes circular folds, villi, and microvilli, all of which contribute to an immense increase in surface area—up to 600 times. These adaptations allow the intestine to efficiently absorb digested nutrients. The circular folds, or plica circularis, create a spiral movement, which slows down the transit of chyme, allowing more time for nutrient absorption. The villi are projections on the mucosa that further increase the surface area and contain networks of blood and lymph vessels to transport absorbed substances away. Each villus is covered with microvilli that further increase the absorptive area and carry digestive enzymes for the final breakdown of carbohydrates and proteins.

Option B is the correct answer as it states that the extensive folding 'greatly increases the surface area of the intestine, which aids in digestion and absorption'. This increased surface area is essential for the digestive process, enabling a large amount of digested food molecules to be absorbed and to meet the body's nutritional needs.