Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!samsung!shadooby!sharkey!atanasoff!drues
From: drues@atanasoff.cs.iastate.edu (Michael E. Drues)
Newsgroups: sci.bio
Subject: Re: The pH of saliva
Message-ID: <2039@atanasoff.cs.iastate.edu>
Date: 29 Nov 89 09:28:48 GMT
References: <18383@bellcore.bellcore.com>
Organization: Dept. of Biomedical Engineering, Iowa State Univ.
Lines: 67
Reply-To:drues@atanasoff.cs.iastate.edu

ephs@roy..bellcore.com (Barbara Chalfonte) writes:


>We have a _raging_ controversy here that standard sources of information have
>failed to resolve.  Is saliva basic or acidic?  I thought acidic, in keeping
>in line with the rest of the GI tract, my office-mate thought basic, being
>the exception to the GI tract.  So which is it?  Having looked at several

Well, it's been a while since I took GI physiology but here goes:

I think the problem stems from the way you have worded your question.
In other words, there's no simple answer.  8^)

You see, saliva contains a mishmosh of chemicals which are a function
of time of day, phase of digestive cycle and probably the surface
temperature of pluto (is there such a thing as a biological constant?
probably not) :-)  Saliva is a buffered solution.  As an engineer, you
can think of this as stable equilibrium, i.e., a ball between two
hills, no matter which way you push it, it will try to come back to
where it started (within limits of course).

Ganong, "Review of Medical Physiology", 1987 [this is at the same level
as K&R in the C language world :-) ] states:

``The pH of saliva is **about** 7.0''   p.406

The buffers in the saliva try to maintain a neutral pH - at this level,
the saliva is saturated with calcium so the teeth do not loose Ca to
the oral fluids.  The buffers also help neutralize gastric acid and
relieve heartburn when gastric juice is regurgitated into the
esophagus.  To complicate matters further, concentrations of some ions
increase and others decrease when flow rates increase or decrease (if
you want the details, see Ganong or something).  BTW, about 1500 mL of
saliva are produced per day.

So what does all this mean?  Well, suffice it to say,

``The pH of saliva is **about** 7.0''

Of course, you could walk around for a week or so with a digital pH
meter in your mouth.  I bet you could do an FFT on it and find a
cercadian (sp?) rythm!?!

Does this help?  If there are any GI physiologists or MDs out there who
would like to correct me on this, then by all means do.  I am afterall
merely an engineer.

After doing a Ph.D. in Biomedical Engineering, I have come to realize
this (EE/CS/Cpr E types listen up!),

Whoever designed the human body didn't use anything as simple as V=iR!!

And of course if you want to talk about a non-human animal, (i.e., a
ruminent- that's like a cow), then *everything* changes!

'nough said.

+-----------------------------------------------------------------------+ 
|   //                  Michael Drues                                   |
| \X/     Internet:     drues@atanasoff.cs.iastate.edu                  |
|         Bitnet:       v2.med@isumvs.bitnet                            |
|         Pony Express: Dept. of Biomedical Engineering                 |
|                       1146 Veterinary Medicine                        |
|                       Iowa State University                           |
|                       Ames, Iowa   50011                              |
|         Phone:        (515) 294-6520                                  |
+-----------------------------------------------------------------------+


Brought to you by Super Global Mega Corp .com