Where does absorption take place in the digestive system?

• A. Stomach
• B. Large intestine
• C. Esophagus
• D. Small intestine

Answer: (D)

Absorption happens primarily in the small intestine because its lining is built for it. The inner surface is folded into villi, and each villus is covered with microvilli, giving a huge surface area for contact with digested food. Nutrients cross the intestinal lining through enterocytes and then enter the bloodstream (for sugars, amino acids, minerals) or the lymphatic system via lacteals (for fats). Digestive juices from the pancreas and bile also help break things down so they can be absorbed more efficiently.

The other parts of the digestive tract don’t specialize in nutrient absorption. The stomach does most of the chemical and mechanical digestion of food and only absorbs small amounts of substances like water, some drugs, and alcohol. The esophagus is mainly a passageway for moving food to the stomach. The large intestine mainly absorbs water and electrolytes and serves as a site for gut bacteria; most nutrients have already been absorbed earlier in the digestive tract.