Title: Small Intestine - Digestive System - MCAT Content
Headings: Small intestine
Small intestine
Practice Questions
Khan Academy
MCAT Official Prep (AAMC)
Key Points
Key Terms

Content: It is where most chemical digestion using enzymes takes place. The jejunum is the middle section of the small intestine. It has a lining which is designed to absorb carbohydrates and proteins. The inner surface of the jejunum, its mucous membrane, is covered in projections called villi, which increase the surface area of tissue available to absorb nutrients from the gut contents. The ileum is the final section of the small intestine. The function of the ileum is mainly to absorb vitamin B12, bile salts, and any products of digestion that were not absorbed by the jejunum. The wall of the small intestine has numerous finger-like protrusions known as villi. On these villi, numerous absorptive cells are present on which microvilli are present. The villi and microvilli increase the surface area of the small intestine that helps in the absorption of food molecules. The small intestine is the site where the digestion of the food, including carbohydrates, fats, and proteins is completed, and the digested food is absorbed.