Which region is the major site of nutrient absorption?

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

Answer: (A)

Most nutrient absorption happens where the surface area for exchange is greatest and the absorptive cells are highly active. In the jejunum, the mucosa is thickly folded and lined with countless finger-like villi and tiny microvilli, creating a vast surface area and a rich brush border with many transporters and enzymes. This setup lets monosaccharides, amino acids, fatty acids, glycerol, vitamins, and minerals be efficiently taken up as chyme moves through. The duodenum mainly handles chemical digestion and only begins substantial absorption, while the ileum specializes in reabsorbing bile acids and vitamin B12, and the cecum in the large intestine handles water absorption. So the jejunum stands out as the major site of nutrient absorption.