Describe 3 adaptations the ileum has that allow it to maximise the absorption of nutrients from its lumen into surrounding blood vessels.

The ileum is lined with simple cuboidal epithelium. This means there is a short diffusion pathway from the lumen of the gut to the surrounding blood vessels. The lining epithelia also has villi and the epithelial cells have microvilli. Both of these features help to increase the surface area of the ileum to maximise absorption. Finally the ileum has a good blood supply. This enables rapid uptake of nutrients as a concentration gradient is maintained between the lumen of the ileum and surrounding blood. This means nutrients rapidly diffuse from the lumen into the surrounding cells and then blood.