ABSTRACT
The d irec t uptake o f soluble m olecules through either a tegum ent o r a m em brane is a physiological process sim ilar to that o f the uptake o f solutes by m am m alian gu t epithelial cells. The process o f absorp tion cen tres round the follow ing m echanism s:
■ Simple diffusion: m olecules are absorbed passively through the m em brane: a process regulated by the m ovem ent of m olecules from a higher concen tra tion in to the para s ite ’s cells o r tissues w ith a low er concen tra tion .
