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Re: Sauropod drinking



There may be some confusion here.  There are no changes in pulmonary artery or
venous pressures at reasonable depths.  Therefore, no hemorrhaging into alveoli.
I'm not sure about depths below 100 ft or so in regards pulmonary circulation
pressures.  What you do is add dead space with a snorkel.

Michael Teuton

Richard Keatinge wrote:

> In article <35AC07C0.247FC09@erinet.com>, Jonathon Woolf
> <jwoolf@erinet.com> writes
> >C. Laibly wrote:
> >
> >>         I remember reading an article in my Princ. of Paleontology course
> >> concerning a professor who tried testing the plausibiliy of this theory
> >> (large sauropods breathing while bodily immersed in water). He breathed
> >> through a hose that would supposedly have given him relative fresh
> >> air and pressure amouns to deal with as that of a submersed sauropod.
> >> He died from congestive heart failure in the process. Then again, a
> >> plesiosaur could breathe. Hmmm. Something to think about...
> >>
> >
> >What makes breathing in water difficult is the external pressure 
> >_differential_
> >between the intake (nostrils) and the lungs. The nostrils are in air at 
> >normal
> >atmospheric pressure of 14.7psi.  The lungs -- well, the pressure on them
> >depends on how deep underwater they are, and how dense the water is.  As a
> >general rule of thumb, the pressure increases one atmosphere for every ten
> >meters of water.  A mere five feet of water, about 2.5psi of added pressure
> >differential, is more than the average human's lungs can overcome.  Anything
> >that wants to breathe with its nose at the surface and its lungs ten or 
> >twenty
> >feet down had better have Brobdignagian lung muscles.
>
> 'snot the lung *muscles* that are the problem.  Lungs work by having a
> really thin (=not very strong) membrane across which gases diffuse
> readily.  The air on one side of the membrane (if you're snorkeling) is
> at atmospheric pressure; the blood on the other side is at atmospheric
> pressure, plus whatever blood pressure is required to drive the
> pulmonary circulation, PLUS the external water pressure.  I really can't
> see any way round that for any credible design of lung; you can't
> snorkel more than a couple of feet or so down, without either collapsing
> your lungs (if you're lucky) or breathing out most of your circulating
> blood volume into what's meant to be air space, like the good professor
> presumably did (I heard the same story in medical school).  And neither
> could a sauropod.
>
> back to lurking...
>
> --
> Richard Keatinge
>
> homepage http://www.keatinge.demon.co.uk