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Learn the toughest concepts covered in Microbiology with step-by-step video tutorials and practice problems by world-class tutors.

21. Principles of Disease

3) Surviving Inside Phagocytic Cells


Surviving Inside Phagocytic Cells

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in this video, we're going to talk about yet another method that some pathogens can use to evade or avoid the immune system and that is through surviving inside of fake acidic cells. So recall from some of our previous lesson videos that we described the process of fargo psychosis in a stepwise manner. And so recall from those videos that when a pathogen is engulfed by a fa go site, that pathogen will enter the Figo site within a fag a zone and the fag a zone will generally fuse with a license um which will allow for the pathogen to be digested and eliminated. Now some bacteria have evolved mechanisms to be able to survive inside of a fake acidic sell even after they have been engulfed and they can do this in three different ways that we have down below in our image and so noticing this image on the outside right here, what we have is our pathogen and of course our fag acidic cell is going to be this big blue cell that you see here. This is going to be our macrophage. And so notice that the pathogen here has obstinance on its surface. And those options allow for the process of optimization that makes the fact that makes the pathogen easier to be engulfed through the process of photosynthesis. And so when the pathogen is engulfed, notice that it is brought into the cell within a faggot zone. Okay, now the first mechanism that some bacteria have evolved to survive inside of fa GO sites is they have evolved mechanisms to escape from the faggot zone before the faggot zone fuses with the license. Um And so what you'll notice here in this image right here at this region, we are showing you how some bacteria have evolved a mechanism to escape the faggot zone. And when they escaped the faggots um they escape. Uh they they're um the fact that they were destined to be degraded and destroyed. Uh and so when they escape they are able to survive within the macrophage. Now another mechanism that some bacteria have been able to evolve over time to survive in fabio sites is that they can avoid or block the fusion of the faggot zone with the license um by producing inhibitory proteins. And so notice here that uh some sometimes right here the step #2 where the faggot zone would usually fuse with liposomes. This step can be blocked and prevented and so that will allow the um the pathogen to survive within the faggot zone and not have to worry about the digestive enzymes from the license. Um Now the third uh possibility here that some bacteria have evolved is the amazing ability to be able to survive inside of the fa go license. Um Even after you know the license ums have fused with the fact zone. And so even when the license soames fused with the fact zone and all of these digestive hydrologic enzymes are there trying to degrade the pathogen. Uh In some cases the pathogens have been able to survive those conditions and avoid being destroyed by the contents of the license. Um and so notice this pathogen here is saying can't kill me because they are able to survive even inside of the fungal license. Um And so there are examples of microbes that are able to survive inside of fabio sites by using each of these three different methods. And so this year concludes our brief lesson on how some pathogens can survive inside of fake acidic cells. And we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.

Which of the following answers is not a mechanism pathogen use to survive within a phagocytic host cell?


Some encapsulated bacterial pathogens are said to be serum-resistant. Serum resistant pathogens avoid the effects of the complement system proteins. How are encapsulated bacteria able to be serum-resistant and avoid phagocytosis?