Acid- Based Balance
Fundamentals of pH
Acids, Bases and Buffers
We are to go through and review a lot
of things that you probably are familiar with.
But we wanna make sure that
everyone is on the same page.
And this will allow us then to delve
in deeper to acid base balance in the body
if we review some Chemistry basics.
So, you remember that the pH
is a logged rhythmic scale.
So, when you have an average or
normal arterial blood pressure pH of 7,4,
it really is a very small
concentration of hydrogen ions.
You can see how many decimal places you are and
that is your concentration of hydrogen ions.
In terms of the body's ability to
change pH, especially in the GI system,
you can go all the way from a pH
of about 1 or 2 pH for about 8.
The pH of 1 will be in the stomach. And the pH of 8
will be the secretions of the pancreas.
So, when you think about pH, it's probably
easiest to start off with a pH indicator strip.
You all use these in Chemistry class at one point.
You take this, you dip it into a liquid,
you pull it out and you see what color came up.
If you get to the more darker colors, such as
a blue, a purple or violet, that is a basic pH.
If you’re at the red end of the spectrum,
that is an acidic pH.
So, we’re going to utilize
this kind of color scheme
as we move forward to try to understand,
what acid- based balance in the body looks like.
So, I have a couple memory tricks for you.
First memory trick, is… oh!
That is our acidic gnome.
Oh! Those are your normal pH gnomes.
And this final one, that is you basic gnome.
We’re going to utilize these
color schemes as we move forward
or utilize our little gnome friends
here as examples
so you’ll be able to think
about as soon as you see one,
whether it’s either acidic,
a normal pH or basic.
So, for go through all the different pH examples
of the fluids of the body besides the blood.
Although the blood is the most important
and we’ll spend the most time on it.
Let’s go through other pH’s in the body.
Gastric secretions I said before, right around
a pH of 1, maybe of a little bit less.
This is because of the hydrogen ion pump,
which is known as an H+-K+-ATPase.
This is what is kicking out hydrogen ions
into your stomach, making hydrochloric acid.
Lysosomes also are acidic.
These are cells, cellular structures
that will breakdown various proteins
once they come in contact with this lysosomes.
Different Chromaffin granules are also very low pH.
If you think about water at 37°C,
it’s pH is 6,81.
The typical cell, is just a little bit basic.
It is about 7,2.
The range though was pretty wide
with any particular cell.
If you undergo anaerobic metabolism,
you’re going to be producing more hydrogen ions
and therefore your pH will be lower.
If metabolism is very, very slow,
your pH could rise very slightly.
Cerebrospinal fluid has a little bit higher pH 7,3,
but here the plasma of the blood has a pH of 7,4.
This is very tightly regulated.
Some of these other pH’s are less
regulated as arterial blood plasma.
The range is plus or minus (±) 0,05.
So, it’s going to be somewhere
between 7,35 and 7,45.
The Mitochondrial inner matrix
within a cell that is about 7,5.
And finally our highest pH
is in pancreatic secretions.
These pancreatic secretions are going
to put enzymes into the GI tubule.
This secretions involve a lot of bicarbonate.
The reason why you have this high
bicarbonate secretions are to buffer the pH
that’s coming directly from the stomach.
So, you’re going through from the stomach into
the small intestine known as the duodenum.
These are ductal cells that secrete the bicarbonate.
and these bicarbonates are secreted
as they leave the pancreatic ducts.