The Plasma Membrane has many functions. It is not just a physical barrier but a means of communication also. How many of you remember the movie Fantastic Voyage? Probably not many – it was filmed in 1966 – but it was a SciFi film about the reduction of a spaceship so it could travel into the human body. If you have not seen the Fantastic Voyage you may have seen the Magic School Bus cartoon where they also took field trips inside the human body. If you were small enough to be injected in to the human body – what do you think the cell membrane would look like to you – what would be some of the ways you could pass that barrier?