mking1
Registered
Dr Deco:
Im not a doctor Im just an old retired engineer with a background in classical mechanics and an absolute minimum in physiology, so I will gladly relinquish all claims of medical benefit to you.
Isnt blood pooling in the lower extremities a result of gravity and poor circulation? And in an atmosphere with a pressure gradient the blood pooling reduction would be attributed to the extremities having a reduce volume? And if your blood circulation was that poor should you be SCUBA diving? I believe we both can agree that barring any medical maladies SCUBA diving doesnt improve blood flow by an appreciable amount if at all? Anyway this is way out of my area.
100day-a-year:
We couldnt disagree more on the subject of a body being compressible or not. Our body is mostly water and water is not compressible, anyway at the pressures we are discussing. There are small voids inside the body but there isnt sufficient volume to cause our bodys to be classified as compressible except locally. An example of this local compressibility is the lung tissue.
Blood, also mostly H2O, isnt compressible either, even when gasses are dissolved. Example: CO2 dissolved in a liquid, i.e. Coke in a bottle, open the bottle and after all of the gas has escaped you will still have the same volume of liquid, discounting evaporation.
Our body tissues are malleable, with the exception of bone, which is not the same as compressibility, i.e. pressure on one part of the body causes a distortion not a reduce total volume. Furthermore, if our bodies were compressible (i.e. allowed to expand or contract without restriction) DCS wouldnt be a problem, we would look real funny after a dive. Oh! Perhaps we are compressible and Im really not this ugly! That would be great if true. But sadly for me it isnt.
It is the gases at reduced ambient pressure coming out of solution and having no place to go is the cause of DCS, i.e. gas bubble pressing against malleable nerve tissue prohibiting or limiting the transmission of signals, or gas bubbles blocking blood flow.
Your statement:
Furtermore the bodies reponse to immersion (vasoconstriction, reduced respiration to name a few)
as far as Im concerned are contradictory to removing gas from the blood system.
I do understand this discussion is about DeltP gradients. Im saying that there isnt a differential pressure between the top of the lung and its bottom because of an ambient pressure gradient. Take a balloon, approximately the size of a human lung, submerge it to a depth and measure its pressure at top and bottom. The result will be the same pressure at any location inside the balloon. The physical size of the balloon may be a smaller diameter at the bottom due to the increased ambient pressure but the top will be larger for the opposite reason. I do admit that these is a pressure gradient threshold where this discussion applies, but these facts are sufficient for the case at hand.
And to answer you question: Where Do we differ from theory? Answer: From top to bottom.
By the way, this isnt theory, its measurable facts.
Miles.
Im not a doctor Im just an old retired engineer with a background in classical mechanics and an absolute minimum in physiology, so I will gladly relinquish all claims of medical benefit to you.
Isnt blood pooling in the lower extremities a result of gravity and poor circulation? And in an atmosphere with a pressure gradient the blood pooling reduction would be attributed to the extremities having a reduce volume? And if your blood circulation was that poor should you be SCUBA diving? I believe we both can agree that barring any medical maladies SCUBA diving doesnt improve blood flow by an appreciable amount if at all? Anyway this is way out of my area.
100day-a-year:
We couldnt disagree more on the subject of a body being compressible or not. Our body is mostly water and water is not compressible, anyway at the pressures we are discussing. There are small voids inside the body but there isnt sufficient volume to cause our bodys to be classified as compressible except locally. An example of this local compressibility is the lung tissue.
Blood, also mostly H2O, isnt compressible either, even when gasses are dissolved. Example: CO2 dissolved in a liquid, i.e. Coke in a bottle, open the bottle and after all of the gas has escaped you will still have the same volume of liquid, discounting evaporation.
Our body tissues are malleable, with the exception of bone, which is not the same as compressibility, i.e. pressure on one part of the body causes a distortion not a reduce total volume. Furthermore, if our bodies were compressible (i.e. allowed to expand or contract without restriction) DCS wouldnt be a problem, we would look real funny after a dive. Oh! Perhaps we are compressible and Im really not this ugly! That would be great if true. But sadly for me it isnt.
It is the gases at reduced ambient pressure coming out of solution and having no place to go is the cause of DCS, i.e. gas bubble pressing against malleable nerve tissue prohibiting or limiting the transmission of signals, or gas bubbles blocking blood flow.
Your statement:
Furtermore the bodies reponse to immersion (vasoconstriction, reduced respiration to name a few)
as far as Im concerned are contradictory to removing gas from the blood system.
I do understand this discussion is about DeltP gradients. Im saying that there isnt a differential pressure between the top of the lung and its bottom because of an ambient pressure gradient. Take a balloon, approximately the size of a human lung, submerge it to a depth and measure its pressure at top and bottom. The result will be the same pressure at any location inside the balloon. The physical size of the balloon may be a smaller diameter at the bottom due to the increased ambient pressure but the top will be larger for the opposite reason. I do admit that these is a pressure gradient threshold where this discussion applies, but these facts are sufficient for the case at hand.
And to answer you question: Where Do we differ from theory? Answer: From top to bottom.
By the way, this isnt theory, its measurable facts.
Miles.
