Which portion of the small intestine is the second and where most chemical digestion is completed?

Which portion of the small intestine is the second and where most chemical digestion is completed?

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

Answer: (B)

Most chemical digestion in the small intestine is completed in the jejunum, which is the middle section. The small intestine starts with the duodenum, where chyme mixes with bile and pancreatic enzymes to kick off digestion. By the time chyme reaches the jejunum, pancreatic enzymes and brush-border enzymes have largely finished breaking down carbohydrates, proteins, and fats, and the lining’s extensive folds, villi, and microvilli provide a huge surface area for absorbing the resulting nutrients. The ileum, the final portion, continues absorption and handles specific tasks like bile acid and vitamin B12 uptake, while the cecum is part of the large intestine. So, the second portion that completes most chemical digestion is the jejunum.

Most chemical digestion in the small intestine is completed in the jejunum, which is the middle section. The small intestine starts with the duodenum, where chyme mixes with bile and pancreatic enzymes to kick off digestion. By the time chyme reaches the jejunum, pancreatic enzymes and brush-border enzymes have largely finished breaking down carbohydrates, proteins, and fats, and the lining’s extensive folds, villi, and microvilli provide a huge surface area for absorbing the resulting nutrients. The ileum, the final portion, continues absorption and handles specific tasks like bile acid and vitamin B12 uptake, while the cecum is part of the large intestine. So, the second portion that completes most chemical digestion is the jejunum.