let's talk about some of the toxin,
injury by chemical agents, and they're just
a few basic take home points about this.
So toxins may act directly.
They may be injurious just because of what
they are as they are hitting the tissue.
not a common poison, used to be the,
the hatters of old
when they make hats
would use mercury chloride
is making the felt,
and that's where the term
Mad Hatter comes from
is from actually mercury
And what it does is it modifies
plasma membrane self hydro groups
by the mercury
And that inhibits
That's very important because
remember, sodium-potassium ATPase
is critical for maintaining the balance
of sodium and potassium within cells.
And if we poison the
sodium-potassium ATPase irreversibly,
then we don't push out sodium.
We accumulate more and more
sodium within the cell,
and with it comes more and more water,
and eventually the cells get so big
and so bloated with water
that they rupture and die.
So direct injury is an example.
Cyanide, we already mentioned that, it
poisons electron transport chain directly,
But then there are a number of poisons
that are not poisonous to begin with,
that are not toxins to begin with,
they are metabolized and then become toxic.
So on this list, acetaminophen,
and those of you who are
vaguely aware of what this is,
the brand name is Tylenol.
Acetaminophen, you're thinking,
Oh, my God, I take that all the time.
It can be toxic.
Well, yeah, If you take too much of
it, it can be.
It gets metabolized
into a toxic compound
that will cause
irreversible liver damage.
Carbon tetrachloride, also very
common in the dry cleaning industry,
will be metabolized to carbon
tetrachloride with free radical.
So metabolites of something
that was not toxic to begin with
can actually be injurious.
agents can be toxins.
Every drug that you will prescribe,
every drug that you may take
will have a therapeutic index, meaning
that at some level it won't be effective,
and another level,
it will be toxic.
And there's a window in
between, that's the sweet spot
where it does what
it's supposed to do.
But if you have too much of it,
you can have a toxic effect.
Acetaminophen, as I just
mentioned, is an example of that.
Isoniazid, which is used very commonly
in the treatment of tuberculosis,
has a very toxic side
effect at higher doses.
And every drug,
every single drug
at sufficiently high enough
level will have a toxicity.
So just keep that in mind.
Therapeutic agents sometimes
can be toxic agents,
and then finally,
physiologic compounds that we think are,
But you know,
those are great things.
Yeah, everything needs oxygen.
And yet if I put you into
a hyperbaric chamber,
100% oxygen and leave
you there for a week,
you will develop
You will develop
damage to your lungs
because of the generation
of oxygen free radicals.
So even oxygen at high enough
concentrations can be injurious.
You're thinking, glucose
well, no, I need that.
That's how I generate
but think about too much glucose.
What's that disease?
So even glucose can be injurious at
sufficiently high concentrations.
And neurotransmitters, well,
that's how the brain works.
We send little messengers from
one neuron to the next one.
We'll in fact, some of those if you're
released in high enough doses locally,
can be toxic to the cell that has
been bathed in those neurotransmitters
and we will get
neuronal cell death.
So things that you may not even
think are toxic can be toxic.
Just to keep that in mind.