2.32 understand how the small intestine is adapted for absorption, including the structure of a villus

Villus: the inside of small intestine is lined with villi and microvilli, folded to increase surface area.
Function: absorb digested soluble molecules into circulatory system for use.

Adaptation	Function
Thin walls	- short diffusion distance so there is an efficient rate of diffusion
Larger surface area due to villi and microvilli	- villi folded to increase surface area so more molecules can diffuse into villi at once, increasing rate of diffusion
Bloodflow	- villi contain blood capillaries, creating strong concentration gradient to allow rate of diffusion

Exams often ask for a drawing of a villus. You need to included 4 main structures of a villus: capillaries, epithelium, microvilli and lacteal.