Which sections comprise the small intestine?

• A. Duodenum, Jejunum, Ileum
• B. Cecum, Ascending, Transverse
• C. Pylorus, Cardia, Fundus
• D. Esophagus, Stomach, Duodenum

Answer: (A)

Understanding the parts of the small intestine helps explain where digestion finishes and where nutrients are absorbed. The small intestine is made up of three sections: the duodenum, the jejunum, and the ileum. The duodenum is the first segment where chyme mixes with bile and pancreatic juices to begin final digestion. The jejunum follows and is the primary site for most nutrient absorption because of its highly folded lining and large surface area. The ileum comes last, absorbing bile acids and vitamin B12, and it ends at the ileocecal valve where contents move into the large intestine. The other options refer to parts of the large intestine, or to sections of the stomach or esophagus, and are not sections of the small intestine.