|The passive net movement of molecules from a region of high concentration to low
|The net movement of molecules with the use of ATP (energy) to move molecules from a region of low concentration to high
|An intrinsic protein across a plasma membrane stimulated by ATP
|Vili and microvilli are used in the absorption of carbohydrates in the small intestine
|They have: A large surface area good blood supply moist lining close diffusion pathway lots of capillaries
|Diffusion in the Villi.
|1. Starch is hydrolysed to make glucose so diffusion can occur 2. glucose is a monosaccharide so can be absorbed 3.in the blood there is a low concentration of glucose 4. diffusion occurs across the epithelial in the blood
|1. NA+ actively transports out of epithelial cell into the blood by na+K+ pump (carrier protein) 2. due to NA+ entering the blood there is now a higher concentration in the lumen compared to epithelial 3. Na+ diffuses into the epithelial down the concentration gradient through a protein carrier 4. Na+ has to couple up with glucose to diffuse in, so glucose also enters the cell 5. glucose goes in the blood by facilitated diffusion