[Music] hi and welcome back to three sighs lessons co uk by the end of this video you should be able to describe how the small intestine is adapted for absorbing the products of digestion over the last few videos we've been looking at the digestive system we've seen that during digestion large food molecules are broken down into smaller molecules by enzymes so for example starch is digested into simple sugars by the enzyme amylase the products of digestion are then absorbed into the bloodstream in the small intestine so in this video we're looking at how the small intestine is adapted for absorbing the products of digestion firstly a small intestine is very long for example the human small intestine has a length of around 5 meters this means that it provides a very large surface area for the absorption of molecules produced by digestion the interior of the small intestine is covered with millions of villi like these july massively increase the surface area for the absorption of molecules this shows a close-up of villi on the surface of the lye we find micro villi and we can see these here micro villi increase the surface area even further now villi have a very good blood supply so the blood stream rapidly removes the product of digestion and this increases the concentration gradient finally the villi have a thin membrane under this ensures that there's a short diffusion path all of these features mean that there's a rapid rate of diffusion of the products of digestion into the bloodstream now any molecules which cannot be absorbed by diffusion are absorbed by active transport and we looked at that in an earlier video remember you'll find plenty of questions on the adaptations of the small intestine in my vision workbook and you can get that by clicking on the link above okay so hopefully now you should be able to describe how the small intestine is adapted for absorbing the products of digestion [Music]