They have very thin walls, only one cell thick, this enables molecules to pass through easily.
They also increase the surface area of the small intestine wall meaning that there is a lot of surface for diffusion to happen through.
On the outside of villi there are capillaries which pick up the diffused food into the blood stream.
no on cares
ReplyDeletestop being rude.
ReplyDeleteVilli also have microvilli each villus is about 1-2 mm long and there are millions of them this means the surface area of the ileum is very large meaning lots of digested food molecules can be absorbed into the capillaries very quickly
ReplyDeleteThere is also the lacteal which absorbs the products of fat digestion and the ileum is quite long around 3-4 metres meaning more absorption can occur
ReplyDeleteI don't think we need to know it in that much detail for gcse but thank you for your input anyway.
Deletei care
ReplyDeleteThe Biology Syllabus has changed.... New Syllabus Blog:
ReplyDeletehttp://igcse-biology-2017.blogspot.hk
More can be found here
ReplyDeletehttp://igcse-biology-notes.blogspot.hk/2017/06/231-describe-structure-of-villus-and.html
this is a comment section for advice and comments to Hannah
ReplyDeleteIf u don't care you don't need to reply
thank you , i have my igcse biology exam tomorow and this question usually comes wit 6 marks ... thank you
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