What is the correct order of the three major regions of the small intestine from the stomach outward?

What is the correct order of the three major regions of the small intestine from the stomach outward?

• A. Duodenum, Jejunum, Ileum
• B. Duodenum, Ileum, Jejunum
• C. Jejunum, Duodenum, Ileum
• D. Ileum, Duodenum, Jejunum

Answer: (A)

After leaving the stomach, the small intestine is arranged in a fixed sequence: the first section is the duodenum, followed by the jejunum, and then the ileum. The duodenum is the mixing and initial digestion zone, where chyme meets bile and pancreatic enzymes. The jejunum has the greatest absorptive surface, handling the bulk of nutrient uptake. The ileum completes absorption, including bile acids and vitamin B12, before material moves into the large intestine. That sequence—duodenum, then jejunum, then ileum—explains why this option is correct.

After leaving the stomach, the small intestine is arranged in a fixed sequence: the first section is the duodenum, followed by the jejunum, and then the ileum. The duodenum is the mixing and initial digestion zone, where chyme meets bile and pancreatic enzymes. The jejunum has the greatest absorptive surface, handling the bulk of nutrient uptake. The ileum completes absorption, including bile acids and vitamin B12, before material moves into the large intestine. That sequence—duodenum, then jejunum, then ileum—explains why this option is correct.