Effects of the Complement System - Video Tutorials & Practice Problems
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Effects of the Complement System
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In this video, we're going to begin our lesson on the effects of the complement system. And so, recall from some of our previous lesson videos that activation of the complement system can result in three possible effects or immune responses. And uh the first of those is going to be called opsonization. The second is going to be lysis of the microbe or microbe cell lysis. And the third is going to be the inflammatory response leading to inflammation. And so uh if you take a look at our image down below, notice that we're showing you the complement system, which we know from our previous lesson videos can be activated by three different pathways. And so all three of these pathways will ultimately lead to the formation of the enzyme C three converse and the formation of this enzyme C three converse ultimately will lead to these uh immune responses, either ization, microbe cell lysis or the inflammatory response. And so really these are the effects of the activation of the complement system. And so as we move forward in our course, we'll be able to talk some more details about each of these effects of the complement system. So this here concludes our brief introduction to the effects of the complement system. And I'll see you all in our next lesson video to talk more details about each of these three effects.
2
concept
Opsonization
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4m
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In this video, we're going to talk more details about ization, which is one of the three effects of complement system activation. And so IZATION is really just a process that makes microbes easier to bind and engulf during the process of phagocytosis, which recall is cellular eating. Now, during the process of optimization, microbes are going to be coated with these molecules called sins. And so sins are really just these small molecules that will bind to the cell surface of microbes. And they can be recognized by cell surface receptors of phagocyte cells. And so for example, C three B is an obstinate and so C three B as an sin, it will bind to the surface of microbes and by binding to the surface of microbes, C three B can make phagocytosis much easier and more effective for phagocyte cells. And so if we take a look at our image down below, notice at the top, we're showing you a map of our lesson that starts with C three converse. And we know that activation of the complement system through either of the three pathways will ultimately lead to C three converse. And C three converse will ultimately lead to one of these three effects of the complement system activation. And here in this video, we're focused on optimization. Now down below, over here on the left hand side, we're showing you a little cartoon. If there is no optimization, then notice that the macrophage which is our phagocyte cell is gonna have a lot more trouble uh phagocytosis. The microbe. And so notice here the microbe is saying, can't catch me And the macrophage is asking why can't I grab you. And so phagocytosis is much more difficult if there is no optimization. Now through ization, which recall is one of the effects of complement system activation. Then these sin molecules uh which are these little blue circles will bind to the surface of the microbes. And so those little sins somewhat act as like little grips that makes it a lot easier for the phagocytose uh for the phagocyte to bind and phagocytose the microbe. And so notice that uh these gloves here are representing and cell surface receptors that allow for the uh phagocyte to bind a lot easier to the microbe. And so notice that the macrophage is saying, ha gotcha now and the microbe here is not very happy saying, oh no. And so basically what we're saying here is that oxidization makes phagocytosis way easier for the phagocyte. Now, uh up here at the top, right, we're showing you a similar image, but we've got our uh macrophage here in blue and it is phagocytosis, this microbe that you see right here. And if we zoom in what you'll notice is that the microbe is going to be covered with C three B, which is the, which is an example of an opsonin. Um And the opsin C three B binds to the surface of the microbe. And so the cell surface receptors of the phagocyte can bind to the C three B opinon. And it makes it a lot easier for the uh phagocyte to phagocytose uh the micro. And so, ultimately, what we're saying here is that optimization is a process that makes phagocytosis much easier and much more effective and efficient. And so, uh this here concludes our brief lesson on optimization and we'll be able to get some practice applying these concepts as well as move forward and talk about the other effects of complement system activation, including microbe clysis and the inflammatory response. So I'll see you all in our next video.
3
Problem
Problem
A pathogenic bacterium that is able to avoid binding with the complement protein C3b would most likely protect itself from which of the following immune responses?
A
Cell lysis of the bacterium.
B
Opsonization.
C
Triggering an inflammatory response.
D
Antibodies binding to the bacterium.
4
concept
Cell Lysis of Invading Microbes
Video duration:
3m
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In this video, we're going to talk a little bit about cell lysis of invading microbes, which is one of the effects of complement system activation. And so multiple complement system proteins can form a complex in cell membranes. Uh and these complexes are referred to as membrane attack complexes. And so membrane attack complexes are commonly abbreviated as MA CS. And so these membrane attack complexes or MA CS consist of multiple complement system proteins that create pores or holes in the cell. And these pores or holes in the cell membrane can cause microbes to die by cell lysis. Now, these membrane attack complexes or MA CS are very effective against gram negative bacteria, but they are not very effective against gram positive bacteria because they have a thick peptidoglycan cell wall that surrounds their membrane. However, the gram negative cells recall uh have an outer uh lipid membrane and the membrane attack complex can affect that outer lipid membrane. Now, the components of the complement system that are involved in the mac formation or involved in the membrane attack complex formation include the complement system, protein C five through C nine. And so, if we take a look at our image down below. Over here on the left hand side, once again, we're showing you our map of the lesson here that's starting with C three converse, which we know results from activation of the complement system. And the formation of C three converts can ultimately lead to one of these three immune responses. And here in this video, we're focusing on microbe cell lysis. And so cell lic of invading microbes occurs when complement system proteins form a mac or M AC uh which is a membrane attack complex. And so notice here, uh we're showing you a microbe and zooming in to this microbe. Notice that uh there is a pore here that's being formed by this membrane attack complex or M AC. And notice that the uh membrane attack complex consists of multiple complement system proteins from C five through C nine. And you can see those complement system components right here. But ultimately, the formation of a membrane attack complex in these gram negative bacteria can lead to cell lysis of the microbe and cell lysis of the microbe can eliminate that microbe and prevent it from causing us harm. And so once again, this is one of the effects of activation of the complement system. And so this here concludes our brief lesson on this topic and we'll be able to get some practice applying these concepts as we move forward. And then we'll get to talk about the third effect of compliment system activation, which is the inflammatory response. So I'll see you all in our next video.
5
Problem
Problem
The complement system can lead to the removal or destruction of invading microbes and the inflammatory response. Which immune response of the complement system is not effective against gram-positive (+) pathogenic bacteria?
A
Opsonization of invading microbe.
B
Inflammatory response.
C
Cell lysis of invading microbe.
6
Problem
Problem
How do membrane attack complexes cause cell lysis of invading microbes?
A
The complexes attack the cell walls of the microbe causing it to be vulnerable to attack by immune cells.
B
The complexes form pores in the cell membrane of the microbe causing the cytoplasmic contents to leak out.
C
The complexes attack the cell surface receptors of the microbe triggering the cell membrane to degrade.
7
concept
Inflammatory Response
Video duration:
4m
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In this video, we're going to briefly discuss the inflammatory response, which is one of the three effects of activation of the complement system. And so, in order to contain the site of damage, eliminate microbes and to restore tissue damage, the inflammatory response may occur. And again, the inflammatory response can be triggered by the activation of the complement system. And so first, we need to recall from some of our previous lesson videos that inflammation is an innate immune response and it is characterized by swelling, redness, heat pain and sometimes loss of function. Now, in this process of the inflammatory response, we're going to see that the complement proteins, C three A and C five A are going to be the most important ones. And so C three A and C five A will induce changes in the epithelial cells that are lining the blood vessels. And uh C three A and C five A will cause those epithelial cells lining the blood vessels to dilate. And uh dilation just means to enlarge. And so the dilation of the epithelial cells lining the blood vessels allows for additional component uh complement system proteins as well as immune system cells to leave the blood and enter into the infected site. And so this is all going to help promote inflammation. Now, C three A and C five A complement system proteins will also cause mass cells to de granulate or release their Granules into the environment. And that will release proinflammatory cytokines or cytokines that promote inflammation. And so if we take a look at our image down below, over here on the left hand side, once again, we're showing you our map of the lesson here. That's starting with C three converse, which we know forms from activation of the complement system. And the formation of C three converts can lead to these three different effects, immune responses, either optimization, microbe cell lysis or the main focus of this video, the inflammatory response. And so here uh with the inflammatory response, notice that it's going to be the uh complement system protein C three A and C five A uh that are going to be most important in the inflammatory response. So they need to be created. So ultimately, what happens here is C three converse, we know cleaves the uh inactive protein C three B into the active fragment C three and C three BC three A is needed. So that's this one. That's right here. And then C three B can combine with other molecules that ultimately lead to the cleavage of C five to C five A and C five B and C five A and C three A. Those are the two that we're mainly focused on. Here. C three A and C five A. So this one and this one. So uh the C three A and C five A can bind to mass cells which recall are very similar to basophils, but they exist in the tissues rather than circulating in the blood. And so when C THREE A and C five A bind to mass cells, it causes those mass cells to release their Granules to de granulate. And when they do that, they release histamine and other pro inflammatory cytokines that promote inflammation. And so notice here, we're in this image, we're showing you a mass cell and we're showing you that C three A and C five A are binding to the mass cell and that causes degranulation. The release of these Granules that contain histamine and cytokines and histamine and cytokines will lead to inflammation. And so uh what that will lead to is the blood vessels dilating and that will allow immune cells to exit the bloodstream into the site of infection. And so notice in this image that you see down below right here that we have uh blood cells that are exiting the bloodstream and into the site of infection and it is leading to the events of inflammation. Now, as we move forward in our course, we're going to talk even more details about the inflammatory response and inflammation. But for now, this here concludes our brief lesson on how activation of the complement system and these complement system. Protein C three A and C five A can lead to this inflammatory response that helps to eliminate microbes. And so we'll be able to get some practice applying these concepts and then uh we'll move on to the next topic. So I'll see you all in our next video.
8
Problem
Problem
Which of the following cellular responses does not occur due to the inflammatory response?
A
Mast cells degranulate releasing histamines.
B
Epithelial cells change shape allow blood vessels to dilate.
C
Macrophages pass through the epithelial cells of blood vessels to the site of injury.
D
Neutrophils form membrane attack complexes to attack invading microbes.
9
Problem
Problem
The main complement proteins involved in the inflammatory response of the immune system are?
A
C3a and C3b.
B
C3a and C5a.
C
C5a and C5b.
D
C5a and C3b.
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