Which part of the digestive tract is responsible for absorbing nutrients into the bloodstream and sending waste toward the large intestine?

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

Answer: (D)

Absorption of nutrients into the bloodstream happens mainly in the small intestine. Its lining is folded into villi and microvilli, which massively increase surface area so digested nutrients like glucose, amino acids, and small fatty acids can pass into blood vessels (with fats entering the lymphatic system first). Digestive enzymes from the pancreas and bile from the liver aid this breakdown, making nutrients accessible for absorption as chyme moves through the intestine. Once most nutrients have been absorbed, the remaining material is propelled toward the large intestine by peristaltic waves, with the ileocecal valve regulating entry. The large intestine then focuses on absorbing water and electrolytes and forming solid waste. This combination of extensive nutrient uptake and transfer toward the large intestine is the reason the small intestine is the correct site.