Which region is the major site for oral absorption?

Which region is the major site for oral absorption?

• A. Stomach
• B. Duodenum
• C. Jejunum/ileum
• D. Colon

Answer: (C)

Absorption from the gut depends on surface area and blood flow. The small intestine provides by far the largest absorptive surface because of the many folds, villi, and microvilli, plus a rich blood supply and many transport mechanisms. Within the small intestine, the jejunum and ileum handle most of the uptake of nutrients and drugs, making them the primary sites for oral absorption. The duodenum contributes some absorption, but not as much as the mid-to-distal small intestine. The colon mainly reabsorbs water and electrolytes and is not a major site for most drug absorption.

Absorption from the gut depends on surface area and blood flow. The small intestine provides by far the largest absorptive surface because of the many folds, villi, and microvilli, plus a rich blood supply and many transport mechanisms. Within the small intestine, the jejunum and ileum handle most of the uptake of nutrients and drugs, making them the primary sites for oral absorption. The duodenum contributes some absorption, but not as much as the mid-to-distal small intestine. The colon mainly reabsorbs water and electrolytes and is not a major site for most drug absorption.