Title: The small intestine microbiota, nutritional modulation and relevance for health - ScienceDirect
Headings: The small intestine microbiota, nutritional modulation and relevance for health
Current Opinion in Biotechnology
The small intestine microbiota, nutritional modulation and relevance for health
Highlights
Graphical abstract
http://dx.doi.org/10.1016/j.copbio.2014.09.005
Introduction
Sampling of the small intestine
The human small intestinal microbiota
Microbiota-driven SI immune development in health and disease
Microbiota impacts on SI metabolism and gut-brain signaling
Targeting the SI ecosystem to improve consumer health
References and recommended reading
References

Content: Box 1
The small versus large intestine, morphometry and function
Along the length of the human small intestine three regions are recognized, that is, duodenum, jejunum and ileum, while the large intestine encompasses the cecum, the ascending-colon, transversing-colon and descending-colon, the rectum and the anal canal. The terminal ileum region is connected to the large intestine and excessive retrograde flow from the large intestine content into the small intestine is prevented by the ileocecal valve. The mucosa in the intestinal tract is composed of the lumen-exposed monolayer of epithelium that overlays the lamina propria (a layer of connective tissue) and the muscularis mucosae (a thin layer of smooth muscle). The small intestinal villi protrude into the intestinal lumen from proliferative crypts, ensuring the large surface area of the lumen-exposed small intestine mucosa that supports the main function of the small intestine, that is, the absorption of digested food. The immune system of the gut is largely organized in the gut-associated lymphoid tissue (GALT) that plays a major role in the development and maintenance of the immune system. In particular the mucosa (i.e. the lamina propria) of the ileal region of the small intestine is rich in immune cells and encompasses the Peyer's Patches. The barrier function of the mucosa is protected by innate and adaptive immune defences, as well as by the mucus layer that lies on top of the epithelial surface. The mucus layer thickness increases along the length of the small intestine, but remains patchy also in the terminal ileum. Conversely, the colonic mucus layer is a dense and thick continuous layer that is much less penetrable. The large intestine mucosa lacks villus structures and is smooth surfaced and contains proliferative crypts.