Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Carolyn on 28/08/2008 02:52:55
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Inspired by Neils question 74 in a series of 476 treadmill sweaty questions, which can be found here:
http://www.thenakedscientists.com/forum/index.php?topic=16704.0
Like Neil, I walk on my treadmill every day, though not at the rapid speed he does, though if I had 4 legs like him I probably could go over 3.5 mph. Also like Neil, I get really sweaty. Lately, I can't stand it. I get super hot and feel like my skin is on fire. I turned my air conditioner down to 55F/12.7C in an effort to keep cool. Didn't help. Tomorrow I'm turning my a/c all the way down, putting my room ran on in front of me and turning on my ceiling fan to high speed.
What I want to know is, will I still benefit from my walking if I don't sweat.
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sweating is just a response to cool down your skin.
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Evaporation is what cools the body. We don't need to sweat in order to evaporate water to cool the skin surface. Sweating is when the excretion of water is faster than the evaporation rate.
Humidity is a very important factor here as high humidity prohibits our ability to evaporate water so more salts spill out onto the surface of the skin along with copious amounts of water, even without exercise.
It’s what happens in the skin and vessels once we have evaporated water that I find fascinating. Evaporation from the skin (not sweating) alters the density of the salts and sugars in the body fluids making them heavier so gravity can pull them back from the skins surface and back into the veins nerve and lymph circulation systems where they stimulate an increased flow as gravity drags on these dissolved minerals and protein colloids in the fluids, this in turn causes a dragging effect on the whole circuit.
I have mentioned the important work of Michel Cabanac on numerous occasions and cannot stress enough how his discovery of altered blood flow in the human scalp and brain through heat and evaporation generated by intensive exercise shows this simple yet hitherto ignored flow and return density driven circulation.
Cabanac places a Doppler probe between the eye and the nose showing normal blood flow from the brain out to the skin. After intensive exercise, the Doppler probe is placed in the exact same spot and now shows blood flow from the skin back to the brain, exactly the opposite flow to the previous recording.
What Cabanac has shown in this exciting experiment is that the flow of blood is flowing back against the pressure driven flow from the heart. There are no valves and no mechanism for this to be explained other than density changes in the bodily fluids.
Caroline. Thank you for this question and long may you continue to work out on life’s everlasting treadmill.
Andrew K Fletcher
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How would evaporation from the skin alone change density of solutes? or have I just misunderstood, and you mean evaporation of sweat from the skin? If you were to spray water on yourself, then wait for it to evaporate, surely the only effect that would have would be a slight cooling?
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Hi Ben
Thank you for your reply.
The same as it does in the leaves of a tree. Water molecules leave the fluid in the skin to the atmosphere and this must change the density of the fluids that remain in the skin. Impossible for it not to! Same happens on the surface of the oceans generating a powerful underwater river that drives the ocean currents as the denser ocean water sinks causing water to be pulled up from the equator.
In the case of the skin we have salt in the surface that shows us how density changes take place. In saliva and tears we can clearly see the salinity is higher than dietary intake.
Below the skin surface the salinity increase caused by evaporation at the skin surface re-enters the circulation and influences the flow due to the effect from gravity, which in turn pulls more water from the circulation back to the skin surface in a simple flow and return system. This means that although density changes are taking place the denser fluids are being constantly replaced with less dense fluids unless there is a problem with the skin like psoriasis. Here the salts increase in density over and above that found in normal skin and the skin dies as a result of it.
Sunlight increases the evaporation and therefore in psoriasis increases the rate of salt accumulation causing the already damaged cells to dehydrate further and flake off. Solar exfoliation produces good results quickly in psoriasis.
So lets have a look at the Dead Sea. Here we have a hyper saline solution rich in minerals, far denser that the skin minerals so there is a movement of water from the skin into the salt solution pulling with it the excess salts from the damaged P skin while at the same time flushing the high levels of potassium and sodium out leaving behind healthy looking skin and exfoliating the dead and damaged skin.
Every single hair has an artery and a vein attached to it. And the drawings showing the circulation beneath the skin surface fits with the density flow theory.
Unfortunately, physiology has not delved below the surface to see what is happening to the salts as they re-enter the circulation. Radio isotopes would undoubtedly confirm this to be the case.
It is possible to absorb toxic substances through the skin, non more so than the deadly toxins from lead used as make up historically and even used today in some countries as Khol http://www.cfsan.fda.gov/~dms/cos-kohl.html
Beethoven also had lead poisoning confirmed from hair samples. So a denser substance can move from the skin into the blood and from the blood out to the skin and hair showing that this pathway is open for any density change in fluids.
Which is worth considering when we force the poorest people in Britain to have mercury put in their in teeth on the NHS and charge a hideous amount of money for resin based powdered glass white fillings to NHS patients when they cost far less to produce than the toxic fillings?
Andrew
How would evaporation from the skin alone change density of solutes? or have I just misunderstood, and you mean evaporation of sweat from the skin? If you were to spray water on yourself, then wait for it to evaporate, surely the only effect that would have would be a slight cooling?
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Sorry, I misunderstood you - I thought you were saying that evaporation from the surface of the skin would change solute density in the skin. Hence asking about water sprayed on the skin.