in our last few videos we've been talking about the morphology of injured tissues and the morphology uh what does a injured tissue look like or an injured cell look like that is reversible that that can actually return to homeostasis it can fix itself and can repair in this video we're going to talk about the morphology of necrosis what does actually a after you have passed the point of no return in the cell is pass the the the damaged point where it can return and fix itself what does it look like from a microscopic perspective and from a gross perspective of necrosis we've been talking about this uh picture here and this picture is very good at explaining several key ideas again the normal cell here is injured we've already talked about this we've talked about this um necrosis part a little bit but I want to talk about it in further detail and I and I forgot to mention that there's three terms that are crucial to dis well not crucial but you know some pathology professors like to pick on these words or and use these words in test because it talks about the nucleus carolis picosas and Caro rexis describe kind of what happens to this nucleus as the cell undergoes necrosis so carolis is actually so this is a cell supposed to be a cell and this is a nucleus and inside the nucleus there's chromatin or DNA and in under and when the cell undergoes Caro in a dying cell in a necrotic cell the DNA is slowly deteriorated and you can kind of see that this that the DNA here is disappearing and that's what karolyis is is just disappearing of the chromatin pnos is you have a cell the same cell in the DNA a or the nucleus and what happens in pnos is the cell this nucleus becomes really small and it becomes condensed and everything starts condensing down on itself kind of right here in nuclear condensation here and then Caro rexus is uh at last the last one is the new nucleus is here or the cell is here and the nucleus kind of kind of starts breaking apart it starts rexus is rupture but I don't think ruptures the correct term medical terminology rexus is ructure and cararo is nucleus so rexus is rupture so the cell becomes starts becoming frag fragment and you have little pieces of the nucleus kind of all all around here so you just have pieces of the nucleus now that's Caro rexis so carolis pnos and Caro rexis your uh pathology Professor might like those on the test so to continue on let's talk about the morphology of necrosis so the first type of tissue necrosis is coagulative necrosis so in the last let's see here in the last uh picture we kind of talked about the microscopic um occurrences or processes of necrosis now we're going to talk about the gross appearance what it look like if I had the tissue in hand what would it look like quag lative necrosis for that I'm going to use a picture out of Robin's basic pathology eight Edition so here is um quag lative let me see if I can probably use white here quag lative necrosis now you see that the the appearance or the structure of the gland or the tissue is still kind of intact that's one of the features of coagulative necrosis now the injury um what it's thought what it's thought to be happening here is that when the the injury happens the structural proteins and the enzymes are denatured and broken down so that's why the arch detect or the the structure of the gland is still kind of intact um and what will happen is that the Luc coytes and phagocytes will come in here and they'll just slowly eat this away and destroy the mass that's here now of this necrotic dead tissue and this injury usually happens due to es schea so loss of blood flow so the blood that was coming in here somehow got blocked this is a prime example of an MI a myocardial infarction or heart attack this is what happens during a heart attack that some part of the blood supply to your heart this is not the Heart by the way but sometime some type of blood flow is blocked to the heart the heart cell part of the heart dies and undergoes coagulative necrosis let's go on to the next one Li of necrosis is usually due to bacteria or some kind of infection um and it under goes let's just say I have a gland here and some bacteria gets in here and um starts killing these tissues starts killing these cells it actually you can kind of see the root word here actually turns to liquid that liqu liquefies the tissue which is kind of a brutal brutal way but the bacteria liquefies this this tissue and it becomes a liquid and um that's the type of necrosis that bacteria usually happens and it's usually yellowish and it usually is you kind of see some pus um also remember from the last thing we talked about quag lative necrosis um usually caused by es schema except in the CNS in the central nervous system in the CNS in the central nervous system if you have aeia it usually undergoes liquefication necrosis rather than quag lative necrosis now that's an exemp and that's an exception only in the CNS that kind of usually happens that observation has been noted several times so on to the next one gangas necrosis is usually referred to as in the lower limb where uh uh blood flow blood flow is blocked somehow so you got blood let's see here you got blood V blood vessels coming down here it's blocked somehow and you get um you get gangrenous uh Gang Green in the in the lower limb and usually that compromise because you got blood flow this compromise to the lower limb bacteria bacteria can get in here and start causing kind of a liquefication necrosis and that is called wet Gang Green I'm sure we've all heard of wet Gang Green and wet Gang Green is when bacteria get in there and then start causing liquefication necrosis but ganger ganger necrosis should be I should put it as a subsection of coagulative necrosis because gangus necrosis is quag um uh coagulative necrosis but in the lower limb and then when bacteria get involved then it turns into liquefication necrosis of the lower limb and that's called wet Gang Green