Question

How is the small intestine adapted for digestion?

Answer 1

The small intestines are well adapted for absorbing nutrients during digestion by: being very long, having villi and microvilli that increase surface area, using muscular contractions to move and mix food, and receiving and housing digestive enzymes and bile that help the breakdown of food.

1. Long length
   The average length of the small intestines in an adult is around 23 feet. It takes food around 8 hours to pass from beginning to end of the small intestines, which ensures there is enough time for digestion to occur.

2. Villi and microvilli
   The small intestines are packed with villi and microvilli that increase surface area of the small intestines, which helps with absorption.
   

3. Muscular contractions
   The small intestines are lined with smooth muscule tissue allowing for a process called Peristalsis which is the wavelike muscular contraction that propels food through the small intestines.

4. Digestive Enzymes
   Enzymes secreted by the pancreas and bile from the gallbladder enter the small intestines and break down nutrients, the three main types of which are proteins, lipids, and carbohydrates.

Sources:
LearnThings, Wikipedia