[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Sauropod drinking



Don't get too dense, just think & you'll overcome

Michael E Teuton wrote:

> 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
>





--
Fight Fugue----remain irrational