Small intestines

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The small intestines are part of the digestive system and are the site were around 90% of all nutrients are absorbed. The small intestine is comprised of 3 key components:

  1. the duodenum
  2. the jejunum
  3. the ileum

The walls of the small intestine are made up of four tissue layers:

  1. the mucosa is specialised in order to absorb nutrients more efficiently
  2. the submucosa layer, which provides the vessels and nerves[1]
  3. the muscularis layer, that is made up of smooth muscle tissue in orderr to aid contraction and move the small intestines
  4. the serosa which is the last layer of the epithelial cells[2].

In order to maximise the rate of absorbtion the walls of the small intestines are folded so that it incresaes the surface area with many finger like projections called villi. To further increase the surface area and the rate of absorbtion, villi also have microvilli on the cell membrane of the epithelial cells, subsequently the rate of absorbtion increases greatly, and more nutrients are taken up.

References

  1. Intestine S. Small Intestine [Internet]. InnerBody. 2016 [cited 5 December 2016]. Available from: http://www.innerbody.com/image_digeov/dige10-new3.html#full-description
  2. Intestine S. Small Intestine [Internet]. InnerBody. 2016 [cited 5 December 2016]. Available from: http://www.innerbody.com/image_digeov/dige10-new3.html#full-description


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