Buffers are crucial biological systems that resist drastic changes in pH, maintaining vital physiological conditions like blood pH within a narrow, healthy range.
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Hi everybody, Dr. Mike here. In this
video, I want to talk about buffers
[Music]
Now, buffers resist drastic changes in
pH. We know that our blood has a pH of
between 7.35 and 7.45. That's worth
putting up. pH of 7.35
to 7.45.
And if the blood pH goes below 7.35,
it's becoming too acidic. If it goes
above, it's becoming too alkalinic. That
means that the concentration of hydrogen
ions, which dictates the pH is either
going to be too much if it goes in this
direction, too many hydrogen ions, or
not enough hydrogen ions if it goes in
this direction. So what happens in the
body is if we don't have enough hydrogen
ions, we need to make more. If we do
have too many hydrogen ions, we need to
reduce it. And this is what buffers do.
They resist these drastic changes in pH.
All right? So for example, I want to
talk about a quick buffer. And a buffer
that looks like this H2 CO3.
And you should know that the definition
of an acid is anything that can donate a
hydrogen ion. So that means that this
carbonic acid can give us a hydrogen
ion. Now if it does give us a hydrogen
ion, what are we left with if we take
one hydrogen out of this? We're left
with one hydrogen, one carbon, and three
oxygen, which is H3.
H3.
And because we stole a positive from
this, it's left with a negative. And
Bicarbonate
Again, it's the concentration of the
hydrogen ion that dictates the pH. So
which donates a small number of hydrogen
ions and leaves us with a weak base.
Now the definition of a base is
something that can mop up hydrogen ions.
It can bind to hydrogen ions which means
if that can bind to that this is a
reversible equation and so this can also
go in
this direction. Now what we have here is
a very simplistic buffer system where if
we don't have enough hydrogen ions the
weak acid will split apart and release
hydrogen ions. If we've got too many it
will bind to bicarbonate and go in that
direction. Now our body utilizes this
reaction but with the addition of some
other parts. For example, carbon dioxide
If you bind carbon dioxide and water,
have a look, there's one carbon, there's
the one carbon. Two + one oxygen is
three oxygen. Two hydrogen, two
hydrogen. If you bind carbon dioxide
with water, you get carbonic acid. So,
let's write these down just for
completion sake. Carbon dioxide
and water. All right?
All right?
And that can split itself apart to
produce these two. So, that's reversible
as well. What we've now drawn up here is
something called the bicarbonate
buffering system. And this is one of the
most important biological buffers that
we have. Now, let me talk about it in
regards to how it actually works. All
right, this end of the equation deals
with the lungs.
This end of the equation deals with
predominantly the kidneys. Now, this is
important because when we look at
imbalances in regards to pH, we can say
if something's wrong here, it could be
metabolic or kidney caused. If
something's wrong here, then it could be
respiratory cause. And this is going to
be the basis of respiratory versus
metabolic acidosis or alkyossis. Right?
That's for another lecture. But let's
think about like this. Let's just say we
do not have enough hydrogen ions in the
body. If we don't have enough hydrogen
ions, the pH is going up. Right? So
remember, it's a reverse logarithmic
equation. Have a look at my previous
video about calculating pH. Right? We
don't have enough hydrogen ions. How do
we create more? Let's have a look.
Carbon dioxide. This is a byproduct of
respiration. Breathe in oxygen. Our
mitochondria utilize that oxygen and it
produces ATP, water, and carbon dioxide.
And we don't like carbon dioxide. We
want to breathe it out. But in order to
go from the cells to our lungs to
breathe out, it has to go in our
bloodstream. So when carbon dioxide hops
in our bloodstream, most of our
bloodstream's water. Inevitably, all our
carbon dioxide is going to be binding to
that water. and it will be producing
carbonic acid. But because carbonic acid
is a weak acid, hates itself, splits
itself apart and produces hydrogen ions.
Which means one way we can increase the
concentration of hydrogen in our body is
through the accumulation of CO2. How can
we accumulate CO2? I'll show you.
Hold your breath. If you're holding your
breath, you're not breathing out. And
this is what happens. Some individuals
who do not have a high enough
concentration of hydrogen ions in their
blood, they may be holding their breath
a little bit. Their breathing will be
different. Let's think of it flipped.
What if we have too many hydrogen ions?
Well, if we have too many, the
bicarbonate will mop it up and produce
carbonic acid, which will then split up
and produce water and carbon dioxide. So
if we are acidic and our pH is too low
because we have too many hydrogen ions,
we end up producing more carbon dioxide
which means the patient may breathe more.
more.
So the respiration can be an indication
of the blood pH. And you can also see if
we don't have enough hydrogen ions, it
goes in this direction. If we have too
many, it goes in this. And this is the
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