00:01
So comparing Necrosis
and Apoptosis.
00:04
In necrosis,
the cells are swollen.
00:07
They've taken up water
because of the lack of
regulation of the normal
ionic environment.
00:14
So they are swollen, edematous.
00:17
In comparison,
the cells in apoptosis are
shrunken, they're smaller.
00:22
They're fragmenting into
little apoptotic bodies.
00:25
The nucleus is variably
changed in necrosis,
there could be
piyknosis condensation.
00:32
Complete destruction,
that's karyolysis,
fragmentation, karyorrhexis.
00:37
In apoptosis, it's mostly a
fragmentation, so they look karyorrhectic.
00:41
The plasma membrane in necrosis,
it's disrupted,
completely punch full of holes.
00:47
In fact,
apoptosis is completely intact.
00:50
So none of the cell
contents leak out.
00:53
The only thing that's different really
about that is the phosphatidylserine.
00:56
The PS has been flipped from the inside
to the outside, saying, "eat me".
01:01
The Contents.
01:03
In necrosis there
is auto digestion,
and then there's leakage of those
cellular contents to the outside world.
01:11
We actually use that when we
think that there's, for example,
been damaged in the
liver or the heart.
01:17
We can look at enzymes leaked from the
liver and the heart in the bloodstream,
and we can characterize
how severe the injury is.
01:26
In apoptosis, cellular contents
are completely intact, so we can't.
01:30
We cannot measure apoptosis by measuring
cardiac proponents, for example.
01:36
The Mediators.
01:37
So in necrosis, it's a calpains,
remember those are the calcium
activated cytosolic enzymes
that help to degrade lipid
and protein and nucleic acids.
01:49
In apoptosis, it's the caspases.
01:53
And in necrosis,
inflammation all the time.
01:56
In fact, as we talk about really
important component of necrosis.
02:01
In apoptosis, no,
no inflammation.
02:04
It's very quiet.
02:06
Finally, just to look at the
DNA fragmentation pattern.
02:09
For example, in necrosis,
as we break down the nuclear material
on the left hand side,
we just get a smear.
02:17
There's all kinds of different
sizes of nucleic acids.
02:21
So the middle band
is just a control
layering of different
sizes of nucleic acids.
02:31
The total right hand of the three
undergoing necrosis is the total DNA.
02:38
Before it gets fragmented, it's large
material that doesn't flow into the gel.
02:43
And on the left hand side of that
left panel, you see a complete smear,
and that complete smear is because
DNA is fragmented all different sizes.
02:52
It just randomly is hit.
02:54
In comparison, like apoptosis.
02:57
You see with the arrow on the right hand
side that we get discreet sizes to our DNA.
03:02
It's cleaving at distinct
points around his stones,
so we get about 200- 220 size
base pair bands all the way up.
03:14
It's called DNA laddering.
03:16
So this says that this is
really well controlled.
03:19
It's not random,
necrosis, that's random.
03:22
So we've talked
about cells dying.
03:25
We talked about how they die,
we've talked about necrosis,
and we've talked about cellular
suicide, which is apoptosis.
03:34
And with that,
we're ready to start talking
about some of the next
stages of pathology.