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21. Principles of Disease

Exotoxins vs. Endotoxin Review


Exotoxins vs. Endotoxin Review

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in this video, we're going to highlight some of the main differences between exa toxins and endo toxins by completing the interactive blinks in this table that you see down below and notice that this table has exa toxins in the middle column. Then it has endo toxin in the far right column and then of course in the far left we have the property that we're gonna be covering. And so in terms of the bacterial source, recall that exa toxins can be produced by either gram positive or gram negative bacteria and so both gram positive and gram negative can be a source of eggs a toxins. Whereas recall that endo toxin specifically is associated with gram negative bacteria only. And so in terms of the location in or on the bacterium where the eggs, a toxin or endo toxin can be found, recall that the exotic toxins are proteins and so they are going to be found within the cytoplasm of the cell on the inside of the cell. And these eggs, a toxin proteins may or may not be secreted into their environments. And so if they are secreted into their environments then of course it would those eggs a toxins would be able to cause toxic effects. However, if they're not secreted into the environment, if they're not actively secreted, they could still be released into the environment. If this cell is lISZT or ruptured, then the components of the cytoplasm may be released and it could cause the toxic effect that way. Now recall that endo toxin on the other hand, is a component of the outer membrane. Recall that the endo toxin is going to be a the lipo Policy Sacha ride or LPS, found in the outer membrane of gram negative bacteria. And so that's what we're showing you right here. This is the endo toxin. And so this leads us to the chemical nature of these substances. Exa toxins recall are going to be made of proteins so they are going to be protein based and that means that they're made of amino acids, chains of amino acids. Whereas the endo toxin on the other hand, specifically refers to the lipO Policy Sacha ride molecule or LPS. And again, that is a component of the outer membrane of gram negative bacteria. Now recall that it's specifically the lipid, a component of the endo toxin, which is gonna be this portion down below right here. That is going to be the toxic portion of the lipo Policy Sacha ride. And of course lipo Policy Sacha rides, they're going to have this lipid a region and then they'll have the Policy Sacha ride region at the top here. The carbohydrate region now, in terms of their ability to form a toxin or the ability to form a toxoid for uh the extra toxins and the endo toxins recall that a toxoid is really just a vaccine against a toxin for most exotic toxins. Toxoid are able to be generated. So the answer is yes, the ability to form toxoid and most cases normally is going to be available for exa toxins. However, for endo toxin uh that is not going to be the case. There is not the ability to create toxoid for endo toxin as of now. Now in terms of the heat stability, it turns out that exa toxins because they are made of proteins, they are going to be sensitive to heat and so they can easily be inactivated by heat under most circumstances. And so things like auto clothing and exposing uh substances too high temperatures and high pressures. Usually the exa toxins will be inactivated. However, the endo toxin on the other hand, tends to be heat resistant. And so that means that other methods of handling the endo toxins are going to need to be implemented to inactivate them and to make them not a concern but heat alone and autoclave. Ng alone. Uh in many cases is not enough to um and activate the endo toxin. Now, in terms of the effect on the human body, Exa toxins can have a wide variety of different effects. They can affect cell functions cause sell licenses, they can affect specific tissues such as the nerves or any part of the nervous system. They can infect the gastrointestinal tract and so they can have several different effects on the human body depending on the type of eggs, a toxin. Um Now endo toxin on the other hand uh can lead to septic shock if it's able to enter into the bloodstream. And so it could lead to things such as fever, weakness, body aches and again septic shock and septic shock could potentially lead to death. And again this is specifically if the endo toxin gets into the bloodstream. But if we look at the toxicity or the ability to cause disease which you'll notice is that for exa toxins the toxicity is generally high and so the presence of extra toxins will generally lead to disease. However, notice that for endo toxin the toxicity is generally low unless the endo toxin gets into the bloodstream. And then if the endo toxin gets into the bloodstream then again it could lead to septic shock and it can be very toxic. But otherwise if the endo toxin remains localized in a specific region of the body and it does not enter the bloodstream and it does not spread, then the endo toxin will have relatively low toxicity under those circumstances. But again uh exa toxins will have higher toxicity and do not necessarily need to enter the bloodstream and spread to other tissues to cause their damage. So that's what makes them higher toxicity. And notice in terms of the lethal dose that exotic toxins can have effects even at very very small concentrations, even small doses of the extra toxins can lead to these effects on the human body. Whereas for endo toxin usually it is going to take much relatively larger um concentrations of the endo toxin for it to have those effects. And again the endo toxin generally needs to enter into the bloodstream in order to create it's toxic septic shock um effects. And so this here concludes our brief lesson where we highlighted some of the main differences between exa toxins and endo toxins. And again 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.

Endotoxins are _________ and need to be in _________ concentrations to cause disease in a host.


Which of the following is not a major difference between endotoxins and exotoxins?


The diphtheria toxin is secreted by Corynebacterium diphtheriae bacteria. This toxin has two components, one that binds the host cell and one that causes disease. Which of the following about the diphtheria toxin is false?