Quote: (Originally Posted by
UKSteve)
For the doubters of the effects of immersion ...try this....
Take a plastic bag and fill it with water. .... hold it and observe its shape.
Now immerse the bag in a bucket of water and observe its shape.. still bulging at the bottom???
Steve
Not a terribly accurate example as the bag is hardly rigid like the body. You might as well say fill a balloon with air under water and observe it's shape and then observe it again at the surface.
I'll have a go with a blood pressure cuff myself next week to see if there is a big difference between head and feet.
This will mean a cuff around my neck, but I don't want to hear any cheering at the back!
Can anyone can cite a reference to the changes in blood pressure that I can look up online?
Quote: (Originally Posted by
dteubner)
If you are vertical in the water then there is an additional pressure gradient. Say you are standing in a pool with your head just under the water. The top of your head is experienceing 1ATA and your feet are at 1.18 ATA. Because blood has essentially the same density as water this gradient abolishes the blood pressure differences described above. So immersion casues a very significant effect on blood flow and blood distribution, as well as eliminating the effect of orientation (head up vs down or whatever).
Had another look at this, if it held true, wouldn't people get a massive rush of blood to the head if they were just under heart deep in a pool?
As I recall air pressure is about 760mmHg, with blood pressure at 130/90 or whatever it is, if the water pressure had too great effect then the lower pressure [systolic?] would be lowe than the water pressure if the heart was 1.2m or more above the feet.
If I'm missing something fine, but the examples given don't relate to the human body as far as I can see.
As with Mrs T and the Higgs boson, anyone able to demonstrate why this happens on a single side of A4 [or a post of no more than 25 lines!] wins a green.