19. Innate Immunity
Effects of the Complement System
1
concept
Effects of the Complement System
1m
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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 the first of those is going to be called optimization. The second is going to be like ISIS of the microbe or microbes, L'll ISIS 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 convert taste and the formation of this enzyme C three converters ultimately will lead to these uh immune responses. Either optimization, microbes, L'll ISIS 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, will be able to talk some more details about each of these effects of the complement system. So this year 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
1) Opsonization
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in this video, we're going to talk more details about optimization, which is one of the three effects of complement system activation. And so optimization is really just a process that makes microbes easier to bind and engulf during the process of Figo site Asus, which recall is cellular eating. Now during the process of optimization, microbes are going to be coated with these molecules called obscene ins And so obstinance 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 fig ascetic cells. And so for example, C3B is an obstinate and so C three B. As an obstinate, it will bind to the surface of microbes and by binding to the surface of microbes, C three B can make fake acidosis much easier and more effective for fig ascetic 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 converts and we know that activation of the complement system through either of the three pathways will ultimately lead to see three converters and see three converters 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 fake acidic cell is gonna have a lot more trouble uh fake gossip toasting the microbe. And so notice here the microbes saying can't catch me and the macrophages asking why can't I grab you and sofa go psychosis is much more difficult if there is no optimization now through optimization, which recall is one of the effects of complement system activation. Then these option in molecules which are these little blue circles will bind to the surface of the microbes. And so those little obstinance somewhat act as like little grips. That makes it a lot easier for the fake ghost toast for the Figo site to bind and fabio santos the microbe. And so notice that these gloves here are representing option in cell surface receptors that allow for the uh Figo site to bind a lot easier to the microbe. And so notice that the macrophages saying, ha got you now. And the microbe here is not very happy saying, oh no. And so basically what we're saying here is that optimization makes Vegas psychosis way easier for the Figo site now up here at the top, right, we're showing you a similar image but we've got our macrophage here in blue and it is fabulous! I toasting this microbe that you see right here and if we zoom in which 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 obstinate. Um and the option in C. Three B binds to the surface of the microbe. And so the cell surface receptors of the Figo site can bind to the C. Three be obstinate. And it makes it a lot easier for the Figo site to follow Saito's uh the microbe. And so ultimately what we're saying here is that optimization is a process that makes Vegas psychosis much easier and much more effective and efficient. And so this year 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 microbes, a license and the inflammatory response. So I'll see you all in our next video.
3
Problem
ProblemA 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
2) Cell Lysis of Invading Microbes
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in this video, we're going to talk a little bit about sell license of invading microbes which is one of the effects of complement system activation. And so multiple complement system proteins can form a complex. And cell membranes. Uh and these complexes are referred to as membrane attack complex is and so membrane attack complex is are commonly abbreviated as M. A. C. S. And so these membrane attack complex is or M. A. C. S. Consists 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 like ISIS. Now these membrane attack complex is or M. A. C. S. 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 have an outer 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 converters which we know results from activation of the complement system and the formation of C three converters can ultimately lead to one of these three immune responses. And here in this video we're focusing on microbes, sell license and so sell license of invading microbes occurs when complement system proteins form a Mac or M. A. C, which is a membrane attack complex. And so notice here, we're showing you a microbe and zooming in to this microbe, noticed that there is a poor here that's being formed by this membrane attack complex or M. A. C. 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 compliments system components right here. But ultimately the formation of a membrane attack complex in these gram negative bacteria can lead to sell license of the microbe and sell license 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 year 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 complement system activation, which is the inflammatory response. So I'll see you all in our next video
5
Problem
ProblemThe 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.
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Problem
ProblemHow 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
3) Inflammatory Response
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, C3 A and C5 a are going to be the most important ones. And so C three and C five A will induce changes in the epithelial cells that are lining the blood vessels and C three A and C five A will cause those epithelial cells lining the blood vessels to dilate and dilation just means to enlarge. And so the dilation of the epithelial cells lining the blood vessels allows for additional component 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, see three A and C five A. Compliment system proteins will also cause Mass Cell's to dig granule eight or release their Granules into the environment and that will release pro inflammatory 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 converts, which we know forms from activation of the complement system and the formation of C. Three converters can lead to these three different effects immune responses. Either optimization microbe sell license or the main focus of this video, the inflammatory response. And so here with the inflammatory response noticed that it's going to be the 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 converters we know cleaves the inactive protein C. Three B. Into the active fragment C. Three A. And C. Three B. C. 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 leads to the cleavage of C. Five and two C. Five A. And C. Five B. And C. Five A. And C. Three A. Those are the two that were mainly focused on here. C. Three and C. Five A. So this one and this one so the C. Three A. And C. Five A. Can bind to mass cells which recall are very similar to bestow fills but they exist in the tissues rather than circulating in the blood. And so one C. Three A. And C. Five A. Bind to mast cells. It causes those mast cells to release their Granules to d granulated and when they do that they release histamine and other pro inflammatory cytokines that promote inflammation. And so notice here 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 mast cell and that causes dig granule ation. The release of these Granules that contain histamine and cytokines and histamines and cytokines will lead to inflammation. And so 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 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 year 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
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Problem
ProblemWhich 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
ProblemThe 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.