The walls of the ileum are folded with finger-like projections called villi. This increases the surface area for absorption.
The villi are about 1mm long. The villi contain muscle and are able to move and mix the contents of the ileum.The villi have thin walls lined with epithelial cells which surround a network of capillaries. The rich blood supply removes absorbed substances away from the ileum maintaining the diffusion gradient.The epithelial cells have microvilli which are finger-like projections of the cell surface membrane that further increase the surface area for absorption.As the products of digestion are absorbed from the contents of the lumen and their concentration decreases they are replaced by new material with a higher concentration of the products of digestion.This maintains the steep diffusion gradient between the lumen and the epithelial cells for absorption.
The villi are about 1mm long. The villi contain muscle and are able to move and mix the contents of the ileum.The villi have thin walls lined with epithelial cells which surround a network of capillaries. The rich blood supply removes absorbed substances away from the ileum maintaining the diffusion gradient.The epithelial cells have microvilli which are finger-like projections of the cell surface membrane that further increase the surface area for absorption.As the products of digestion are absorbed from the contents of the lumen and their concentration decreases they are replaced by new material with a higher concentration of the products of digestion.This maintains the steep diffusion gradient between the lumen and the epithelial cells for absorption.