This whole theory about lungs/not lungs absorbing nicotine. Irrelevant.
The process seems to be happening, and where ever the vapor eventually deposits it's load of nicotine, it must somehow be making it's way to the brain's receptors. Or we wouldn't be bothering ourselves with whatever method of nicotine delivery we are using. And the strength of the liquid we know we can tolerate or not tolerate.
If it is absorbed by mucous membrane, mouth, nose, throat, or lungs it's absorbed. Trying to make sense of the studies done with patches, gum, inhalers, etc., the one bit of information that comes through is that absorbtion is faster with cigarettes, slower with any other means. Why that is is hard to discern from any study, but then again I am not a molecular scientist either. All we know is that we receive satisfaction for our efforts through inhaling vapor from PV's. Studies would have to be done IMHO of the mechanisms of the brain itself, which would take years of study just to verify the testing procedures, what the method of comparisons would be, and millions of dollars to do all of these studies to do a study, then technological development of scanning and sampling devices! Then someone would surely be handy to try to question or nullify the results. And the whole cycle would start all over again, by that time I don't think I'm going to be giving a rat's @$$ about it all. Today the question is, WHAT are we addicted to? If indeed we are addicted to anything. Maybe we just happen to like nicotine, as I like a Milky Way bar once in awhile. This is the same question that parents of Down's Syndrome children or MS victims or Autistim, and a host of maladys want to find the answer for. What happens, how does it happen and how do we fix it. I don't think right now today we can find difinitive answers. Or another way to think about it is why do I have ADD, and why doesn't my brain allow me to have 100% instant recall, or 100% Photographic memory. Science seems to be only trying to define the question, so far. Stay Tuned!