<P> Diffusion is the net movement of material from an area of high concentration to an area with lower concentration . The difference of concentration between the two areas is often termed as the concentration gradient , and diffusion will continue until this gradient has been eliminated . Since diffusion moves materials from an area of higher concentration to an area of lower concentration , it is described as moving solutes `` down the concentration gradient '' ( compared with active transport , which often moves material from area of low concentration to area of higher concentration , and therefore referred to as moving the material `` against the concentration gradient '' ) . However , in many cases ( e.g. passive drug transport ) the driving force of passive transport can not be simplified to the concentration gradient . If there are different solutions at the two sides of the membrane with different equilibrium solubility of the drug , the difference in degree of saturation is the driving force of passive membrane transport . It is also true for supersaturated solutions which are more and more important owing to the spreading of the application of amorphous solid dispersions for drug bioavailability enhancement . </P>
<P> Diffusion is the net movement of material from an area of high concentration to an area with lower concentration . The difference of concentration between the two areas is often termed as the concentration gradient , and diffusion will continue until this gradient has been eliminated . Since diffusion moves materials from an area of higher concentration to an area of lower concentration , it is described as moving solutes `` down the concentration gradient '' ( compared with active transport , which often moves material from area of low concentration to area of higher concentration , and therefore referred to as moving the material `` against the concentration gradient '' ) . However , in many cases ( e.g. passive drug transport ) the driving force of passive transport can not be simplified to the concentration gradient . If there are different solutions at the two sides of the membrane with different equilibrium solubility of the drug , the difference in degree of saturation is the driving force of passive membrane transport . It is also true for supersaturated solutions which are more and more important owing to the spreading of the application of amorphous solid dispersions for drug bioavailability enhancement . </P>
passive movement of a solute by carrier protein is called
passive movement of a solute by carrier protein is called
Diffusion
Diffusion