salt content of cells

Jeanne L. Blackwell afn17228 at freenet3.freenet.ufl.edu
Wed Oct 4 08:16:16 EST 1995


<cotegl at ncaur1.ncaur.gov> (G. Cote) <cotegl at ncaur1.ncaur.gov> wrote:

> In article <44juh8$khb at ixnews3.ix.netcom.com>, chimo at ix.netcom.com
> says...
> >
> >I am a high school biology teacher interested in finding out the salt
> >content of human cells, preferably lung cells.  Is it true that the
> >salt content of these cells is isotonic with 'typical' seawater?  I am
> >in a debate with another biology teacher about the subject.  I've heard
> >that you are more likely to survive a near drowning in seawater other
> >than fresh water.
> >
> >Lori Karn
>
> "Typical" seawater contains approximately. 2.5% to 3.5% NaCl by weight,
> depending on location.  On the other hand, human blood serum contains
> approx. 0.9% NaCl by weight.  Different body tissues may vary slightly,
> but in general, their salt concentration should be nearly isotonic with
> blood serum, i.e., 0.9% NaCl (w/v).  Other solutes in serum may bring the
> total osmotic pressure up, especially glucose, proteins, etc.
>  As far a drowning is concerned, lungs full of water cannot breathe,
> regardless of the salt concentration.  Water temperature does play a
> role, though, with colder water slowing down metabolism and initiating
> what is known as the "diving response".  Some victims, especially young
> children, have survived immersion in ice-cold water for extended periods
> (over 20 minutes in one case, if newspaper accounts can be believed).
>
Actually, I remember this question from an undergraduate physiology
course - the general idea was that in fresh water, as the osmotic
pressure causes movement of water into the cells lining the lung, these
cells burst, causing hemorrhaging to occur. Cellular damage is supposed
to be more extensive in the case of fresh water, as opposed to in the
hypertonic environment of the salt water. The osmotic pressure is in the
opposite direction in the salt water, so you don't get burst cells.
(Near-drowning victims need to be observed for complications due to lung
damage in any case, I understand.)



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