Short / Long answer type questions.
What are the four structural features that enhance the effectiveness of the small intestine for absorption and digestion?

The structural features are:

• The inner surface of the small intestine is not flat but thrown into circular folds, which not only increase surface area but aid in mixing the food.
  
• It has a large number of finger-like projections called villi that increase surface area for absorption. Each of the epithelial cells in the surface of the villi has a brush border of microvilli that further increases the capacity of absorption by increasing the surface area and also secretes certain enzymes necessary for digestion.
• Lymphatic system (lacteals) and the blood vessels that are well connected to the villi and microvilli and aid in the absorption of food.
• It also has cells such as goblet cells and the paneth cells that secrete mucous and anti-bacterial defense substances