Mailing List Archive Mailing List Archive
Rich <deepreef@bi*.bi*.ha*.or*> said: >Some people (myself included) have a few moments of minimal or virtually >no narcosis immediately upon reaching depth after a direct descent (to, >say, 200 ft. on air), and then the narcosis GRADUALLY increases over the >course of the dive at a steady, almost linear rate (controling for levels >of exertion, stress, etc. - factors with more direct affects on narcosis >intensity). No panic or fear or confusion or anything like that involved. >To me, this seems intuitive for how narcosis should become manifest - >gradually increasing throughout the dive as more nitrogen gets into more >tissues and hinders more neural transmissions. (BTW, by "gradual" I mean >over the course of 10-15 minutes....) This sure makes both physical and physiologic sense for exactly the reasons you state. The increased nitrogen is first presented at the lungs and travels via blood to then diffuse across an endothelial cell and then across who knows how many intervening cells. All of this should take time. I am hard pressed to come up with a plausible explanation invoking inert gas transfer to explain the early then gradually improving effect. I guess this must be some other phenomenon including maybe just psychological except that there seem to be some very experienced divers who describe this. I can't wait for the answer :-)! >'clear up' throughout the course of the dive. I think your explanation of >"mental stamina" and focusing on a particular task may well account for >this. Because it seems to be a fairly consistent pattern (regardless of Seems logical but I don't know how to test it well. >brain". On the other hand, I had a very interesting discussion with Sheck >Exley last January wherein he shared some experiences which suggest there >really is a physiological adaptation (based largely on his experiences >with symptoms of HPNS on his ultra-deep dives with relation to the level >of "short-term" narcosis adaption). He explained a hypothesis involving >cellular-level responses to repeated exposures of high PPN2 & PPHe, but I >can't recall the specifics. Much of the interesting stuff in physiology involves the myriad and very powerful ways in which cells, tissues and organs maintain homeostasis (basically stay alive). Many of these we are just coming to understand and your list (Sheck's hypotheses) will hopefully be understood in our lifetime. It is amazing to me that an organism that mostly developed at sea level seems to have adaptations that work at great depth. Maybe I have a whale as a close relative. Tom
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]