Absorption in the small intestine

• The products of digestion are absorbed in the bloodstream in the small intestine
• The small intestine is very long (5m) this provides a large surface area for the absorption of products
• The interior of the small intestine is covered with villi these largely increase the surface area for absorption of molucles
• On the surface of villi there are microvilli which increase the surface area further
• Villi have a good blood supply so the bloodstream rapidly removes the products of digestion this increases the concentration gradient for difussion
• The villi have a thin membrane this insures a short diffusion path
• Any molecules that can not be absorbed by diffusion are absorbed by active transport