Discussion in 'Chemistry' started by Asguard, Mar 24, 2008.
did you see that chemical burn scene in fight club?
Then the difference between solid and liquid is one of perception.
Enmos yes but the solids are technically "flowing"
everything is liquid and it's just a matter of viscosity?
Not entirely true.
Some things we normally call "solids" are distinct from liquids - they are also called "crystals."
Crystals are not liquids because they can resist flow on any time scale you wish to consider. For example, window glass is really a liquid but a NaCl crystal is not.
A crystal of NaCl will keep its cubic structure for all eternity in a gravitational field much stronger than the Earth while sitting on a table, but a "lump of glass" will take on a "flat pancake shape" constantly growing thinner until the surface tension prevents it from making any more surface from the gravitational energy it can release by getting still thinner. (It takes energy to make surface. - Grinding will always require energy for this reason.)
This might be nit-picking, but I think it's not the CO2 level in your blood that causes that feeling--I think it's the CO2 level in your lungs. I believe that lung tissue is very sensitive to elevated CO2 levels, which is why your lungs feel like they're burning when you try to hold your breath too long.
webgrunt what the hell are you talking about?
The rise in CO2 acidifies the blood which then causes the CSF to become slightly acidic which triggers the part of your brain in charge of the respitory drive to send a nerve impulse to the diaphram and intercostals to get them to open the space in the thoracic cavity which then causes a pressure inbalance which sucks air into the lungs
That is interesting and more plausible than web grunt's POV, but I doubt your POV also. As I recal the CSF is made by some pink tissue (the coroplexes or some name like that) on the walls of the 4th ventrical approximately at the rate of 0.3 CC / minute. The CSF does track the blood plasma chemistry rather well. It flows out thru vents in the dura surounding the Caudiquine (latin for "horse's tail" as down there the spinal cord is just individual nerve fibers.)
I know all this as long ago I designed a glucose sensor for closed loop insuline control implated system, which sensed the optical rotatation of sugar in the CSF - impossible to sense blood sugar in the blood long term with an implantaqble sensor, still I think. (My system would have worked, but even I did not like the idea of fusing three vertibra for a rigid, fixed-length optical path thru the CSF, so we only built an open loop control system. (The implantable insuline pump now sold by Medtronics. They got their start from APL/JHU also with the rechargable heart pacer we made using space technology*, but now expendable batteries are much better and the circuits require much less power so none are still sold.).
Here is what I believe happens to make you breath, however you may be correct, but not the "via CSF part" - just the pH change in the blood could be quickly sensed:
The blood vessels in the brain are unique in that they dialate with increased CO2 concentrations. (that is for sure) This casues the local blood flow to increase. The excess local CO2 is caused by unusually intense activity in the local nerves. This is why some types of radioactive isotope injected into the blood can be used to map out what parts of the brain are most active with certain tasks, like doing mental math etc. Now days I think these brain studies are more commonly done by Magnetic Resonance Imagining, not with many detectors determining where the radioactive source strength has increased, but radiographic imagining is cheaper and still used I think to locate anormalities such as a brain tumor, before the surgeon goes in to remove it.
No one really is sure why migrain head aches occur I believe that the expansion of the brain blood vessel in response to elivated CO2 levels may not only be sensed bu nerves in these blood vessel walls but also be the cause of some migraine head aches. Cerainly if he whole brain were to try to expand its blood vessels (when holding your breath) that could be sensed and be the cause of the strrong urge to breath.
I do not like the CSF explainiation as with only 0.3cc being produced/ per minute and many CC within the dura, it does not appear to be sesponding quickly eneough to be the cause of the urge to breath. The expansion of the blood vessels in the brain is of the correct time scale -speed of response.
Also some people prone to migranes can trigger them by breathing inside a paper bag - this is sometimes done to cure hick ups -but my experience with this is that it does not work for me in the rare occasions I have both had the hic-cups and tried breathing inside a paper bag.
*BTW and more on the thread: APL recently got a Nasa contract for what may be the mostdifficult unmanned mission yet. Go thru the solar corona and maesure it. launchis in 2015 just getting there will take seven swing by gravit assists from Venius. As craft goes thru the corona itr travels 125miles / second! in a solar flux 500 times more intense than near Earth. - We will know some time about 2020 if solids burn. ApL has space craft ont eh way to Pluto now - the fastest rocket ever launched. Sure it is hard to go to Pluto but o go the the solar corona is very harder - takes more change in orbital energy. Few understand this - you can not just fall into the sun form earth -great energy change is required. - why seven swing bys of Venus will be used, yet the contrract is still for 750 million dollars. (surely more than a billion when final payment in 2015 with the inflation adjust clases etc. APL will bring this most difficlut of all in on schedule and under budget, I bet - just as they did the plotuo shot or knocked down the failed spy satellic last year on the first try. They are a great organization - I worked there 30 years on many interesting and very different things. Sorroy I must sing off now without my normal spell check for my typing and dyslectic errors.
I will get back to you on that, i have to get my A&P book out tonight anyway so i will check out the respitory drive while im at it. It DEFINITLY has nothing to do with the lungs thats for sure. Its DEFINITLY blood and CO2 related (and i think its related to adcification but i will double check that)
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