00:00
Right now, let's just look
at an example of what happens
in terms of protein synthesis,
they kind of give this some reality.
00:06
So here we have a
bit of a membrane.
00:09
This would be rough
endoplasmic reticulum.
00:11
And on the surface of the
rough endoplasmic reticulum
is ribosome it's translating
its protein through
into the middle of the
looming of the rough ER.
00:20
Life is good,
except now we have ingested
or inhaled or done something
where we've gotten a fair little
high dose of carbon tetrachloride.
00:32
This is a compound used in dry
cleaning fluid, fairly common,
and we metabolize it in enzymes that
live in the endoplasmic reticulum.
00:43
In particular the cytochrome p-450
system, which is not a detoxifying system.
00:49
It is a solubilization system.
00:52
It's taking something
that's lipid soluble
and converting it to something
that is more water soluble,
so it could be excreted.
00:59
Cytochrome p-450,
in that same endoplasmic reticulum,
takes our carbon tetrachloride
and converts it to carbon
trichloride with a free radical.
01:10
Oops, now we have a free radical in
the middle of a whole bunch of lipid.
01:15
What's gonna happen?
It can be predicted.
01:18
We're going to start in an autocatalytic
way, breaking down that entire membrane,
and we're getting more and
more and more free radicals
as because it's autocatalytic.
01:27
As we now break down the rest of
lipid, and the lipid is falling apart.
01:33
Our membrane is dissolving,
it's become a detergent.
01:36
When that happens,
our ribosome goes away.
01:39
It can't bind anymore,
so we're protein synthesis goes to zero.
01:43
Not so good.
01:46
Fortunately, we do know that we're
going to encounter things like this,
so we have ways to sup up,
to scavenge free radicals.
01:54
And vitamin E is one of those,
it lives in membranes in various places,
including the
endoplasmic reticulum.
02:00
And it can be a free radical scavenger,
so it is a way to potentially stop this.
02:05
There are limits, you only have a certain
amount of vitamin E in your tissues,
so you cannot make infinite amounts of free
radicals and expect to get away with it.
02:13
But it is a mechanism by
which we protect ourselves.
02:17
And now there's some
other mechanisms
by which we protect
ourselves from free radicals.
02:23
So here's the effect on
cellular activities and death.
02:27
If we look at our normal
rough endoplasmic reticulum,
and our normal mitochondria,
they have a certain structure and
architecture, and they look fine.
02:36
If we now hit them with a free radical,
in this case, carbon tetrachloride.
02:41
The ribosomes have left rough ER
and our mitochondria are swollen.
02:45
So we're not making protein
and we're not making ATP.
02:49
When that happens,
we will get cell death.
02:51
So this is on the right
hand side is a liver.
02:54
In an experimental animal that's
been exposed to carbon tetrachloride,
and we're getting these
areas of necrosis.
03:01
Cell death, cellular homicide and
those are pointed to with the arrows.