Necrosis vs. Apoptosis

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.