page_title: Small intestine
section_title: Microanatomy
hierarchical_section_title: Small intestine / Structure / Microanatomy
caption_attribution_description: English: This is a cross-section of a small intestine showing the layers, from the serosa into the lumen.
context_page_description: The small intestine or small bowel is an organ in the gastrointestinal tract where most of the end absorption of nutrients and minerals from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion.
  The small intestine has three distinct regions – the duodenum, jejunum, and ileum. The duodenum, the shortest, is where preparation for absorption through small finger-like protrusions called villi begins. The jejunum is specialized for the absorption through its lining by enterocytes: small nutrient particles which have been previously digested by enzymes in the duodenum. The main function of the ileum is to absorb vitamin B₁₂, bile salts, and whatever products of digestion were not absorbed by the jejunum.
context_section_description: The three sections of the small intestine look similar to each other at a microscopic level, but there are some important differences. The parts of the intestine are as follows:
caption: This cross section diagram shows the 4 layers of the small intestine wall.
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