diffusion
transport that arises from the molecular agitation that exists in all systems above ab. 0 and from the simple statistical tendency for such agitation to carry more molecules out of regions of relatively high concentration than into such regions
permeability
the ease with which the solute can move through the membrane by diffusion
which two substances cannot be pumped?
water and oxygen
diffusion equation
J=D(c1-c2)/x^2