Most absorption occurs in which part of the digestive system, which features villi?

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

Answer: (D)

Most absorption happens where the lining has villi: the small intestine. Villi are tiny finger-like projections that dramatically increase the surface area available for absorbing nutrients. Each villus is rich in blood capillaries and a lymphatic vessel, so absorbed nutrients can quickly enter the bloodstream and lymphatic system. This setup lets digested carbohydrates, proteins, fats, vitamins, and minerals be taken into the body efficiently as chyme moves through the duodenum and jejunum (with continued absorption in the ileum). By contrast, the stomach mainly digests and passes some substances into the bloodstream; the esophagus just transports food; and the large intestine reabsorbs water and electrolytes but has no villi, so it isn’t the main site of nutrient absorption.