Cells of the Immune System: Agranulocytes - Video Tutorials & Practice Problems
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1
concept
Aganulocytes
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3m
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So now that we've discussed the granulocytes in our previous lesson videos. In this video, we're going to begin to discuss the a granulocytes, which includes cells of the innate immune system. Now, the a granulocytes are white blood cells or leukocytes with cytoplasmic Granules. However, unlike the granulocytes, the cytoplasmic Granules of a granulocytes are not visible under a light microscope. And because those cytoplasmic Granules are not visible under a light microscope, we refer to them as a granulocytes. Now really there are two main types of a granulocytes that we have numbered down below. The first main type of a granulocytes are going to be the monocytes and the second main type of granulocytes are going to be the lymphocytes. Now, the monocytes are leukocytes or white blood cells that circulate in the blood and can further develop into either macrophages or dendritic cells. And so if we take a look at our image down below, notice that we're showing you our map of the lesson on the cells of the immune system. And so notice at the very top, we have our hematopoietic stem cell and this hematopoietic stem cell can differentiate into the common myeloid progenitor cell or the common lymphoid progenitor cell and give rise to all of these other different cell types that we have down below. Now notice the ones that are in gray are the ones that we are not focusing on because we've already discussed them in our previous lesson videos and this includes the granular sites which we already talked about. So in this video, we're focusing specifically on these cells over here which are once again the a granular sites. So we can go ahead and label them here as the a gran u low sites. And these a granular sites again includes the monocytes which you see here and these lymphocytes which you see over here. Now, the monocytes, as we just discussed up above in the text, the monocytes are leukocytes or white blood cells that can circulate in the blood and further develop into either macrophages or dendritic cells. And so taking a look at the image down below notice we have the monocytes here and they can further differentiate into either macrophages or dendritic cells. And we'll get to talk more details about the monocytes, macrophages and dendritic cells as we move forward in our course. Now, the lymphocytes once again uh include these cells that we see over here uh which are the natural killer cells, T cells and B cells. Now notice that the natural killer cells are part of innate immunity. However, the T cells and B cells are part of adaptive immunity. And that's why they have that little star symbol next to their name right up here. And so, um what we are saying here is that the lymphocytes includes leukocytes involved in adaptive immunity. And the ones that are involved in adaptive immunity specifically refer to the T cells and B cells. Now, adaptive immunity is a topic that we'll get to talk a lot more about in separate videos much later in our course. And so uh that's something to keep in mind. And so uh moving forward here in our course, we're going to talk more details about these a granulocytes starting off with the monocytes, macrophages and dendritic cells and then moving on to the lymphocytes. And so this here concludes our brief introduction to the A granulocytes and I'll see you all in our next video.
2
concept
Monocytes
Video duration:
7m
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In this video, we're going to begin talking about monocytes and the cells that derive from monocytes. And so these monocytes are capable of developing into one of two main types of phagocyte cells or cells that are capable of performing phagocytosis or cellular eating. And so these two main types of cells are going to be the macrophages and the dendritic cells. Now, the macrophages are once again, phagocyte cells, meaning that they're capable of performing phagocytosis. And they also serve as sentinel cells, which we call our lookout or guard cells that act as scouts. And so these macrophages are capable of responding directly to an infection to help eliminate an infection, but they can also alert other host defenses as well. And that is really what makes them sentinel cells. Now, there are many different types of macrophages found in different types of tissues. And we refer to these macrophages as resident macrophages and so resident macrophages as their name implies, they reside permanently in specific tissues, which means that they remain stationary in the tissues and they don't really migrate around to other tissues, they reside in the tissues. And so these resident macrophages because they reside in the tissues, they will already be pre in the tissues. Whenever those tissues get damaged and microbes uh invade those tissues, they'll already be present and ready to respond because they reside permanently in those specific tissues. Now, other macrophages we refer to as wandering macrophages and as their name implies, they wander around or they move around through the blood to other sites of infection. And so these wandering macrophages can be recruited to a site of infection. And again, they travel around or wander around through the blood circulate through the blood and they can leave the bloodstream to a site of infection when they are recruited. Now, giant cells refer specifically to macrophages that have fused together and the fusion of macrophages uh creates these giant cells and the giant cells because they have, they consist of fused macrophages, they have increased destructive abilities. Uh And so, if we take a look at our image down below over here, on the left hand side, we're specifically focusing in on the macrophages. And so, uh what you'll notice is that here, we're showing you an image of the tissues, the skin here and notice that the t the skin here has been damaged, that there's some kind of damage here. And uh there's some kind of sharp object that has penetrated into the skin. And microbes are now infecting this uh open wound and notice that there are already some macrophages that are present in the tissues already. And we refer to these as resident macrophages because they reside, they are living in the tissues and they're already present and ready to respond whenever any of our tissues get infected. Now, wandering macrophages, on the other hand, they circulate through the bloodstream. And so as they circulate through the bloodstream, they can be recruited to a site of infection. And so the resident macrophages reside and remain stationary within a specific type of tissue. Whereas the wandering macrophage can circulate through the bud and move to other locations and be recruited to sites of infection. Now, uh notice that uh the second main type of cells that monocytes can develop into are going to be the dendritic cells. And dendritic cells are also serve as phagocytes, but they are mainly going to be important as sentinel cells which again are lookout or guard cells that act as scouts. And so their job is to sense and detect the signs of microbes and then they can alert other immune system cells and activate other immune system cells. So these dendritic cells, they are sentinel cells with long appendages and uh they reside in tissues and they are capable of alerting and uh initiating the adaptive immunity and adaptive immune responses. And so they can alert and activate B cells and T cells. And so uh we'll be able to talk more about this process of dendritic cells, alerting and initiating adaptive immunity. Later in our course, when we're talking more about adaptive immunity. Uh But ultimately, here, what we're saying is that um these dendritic cells can ingest uh pathogens in the tissues and they can ingest those pathogens break them down and then present pieces of those pathogens um to cells of the adaptive immune system in order to activate those adaptive immune system cells. And so once again, we'll get to talk more about this later in our course. But down below, we're showing you a little image of these dendritic cells. And so these dendritic cells have these long appendages as you see here that project out and uh here what we're showing you is an interesting image. Uh Here is a um uh a micrograph of what these dendritic cells can look like under a microscope. Uh notice that they have these long appendages that stick out. OK. And uh notice here that we're showing you the intestinal lumen. So this is our uh intestines, for example, our large intestine and uh some of the substances that we end up eating get broken down into uh antigens. And these antigens could be potentially from microbes that we have uh eaten. And so um what you can see here is that the dendritic cells which are uh down below, they have these long appendages that can take little samples of the antigens in our intestine and then they can ingest those antigens, break them down and process them and then present them on their surface. So notice that these little pieces of antigen are presented on their surface. And here's a second dendritic cell doing something similar. And then these dendritic cells can go on to activate other adaptive immune system cells like B cells and T cells, which once again, we'll get to talk more about that process later in our course, when we're focusing on adaptive immune system. But for now, this year concludes our brief lesson on the monocytes and how they can develop into macrophages and dendritic cells. And so we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.
3
Problem
Problem
All of the following are major differences between macrophages & neutrophils except which of these answers?
A
Macrophages can perform phagocytosis while neutrophils cannot.
B
Macrophages kill microbes by “eating” them. Neutrophils kill microbes with hydrolytic enzymes and/or phagocytosis.
C
Neutrophils circulate the bloodstream while resident macrophages reside in tissues.
D
Neutrophils are granulocytes while macrophages are agranulocytes.
4
Problem
Problem
Monocytes can differentiate into which types of immune cells?
A
Basophils & macrophages.
B
Neutrophils & dendritic cells.
C
Macrophages & dendritic cells.
D
Mast cells & macrophages.
5
concept
Lymphocytes
Video duration:
3m
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In this video, we're going to begin our introduction to lymphocytes. Uh recall that these lymphocytes includes leukocytes that are important for adaptive immunity. But really, we're focusing specifically on the T cells and B cells when we're talking about lymphocytes important for adaptive immunity. Now, adaptive immunity is a topic that we'll get to talk a lot more about later in our course. And they will be covered in other videos. Uh But really, the two major groups of lymphocytes that are important in adaptive immunity are once again going to be the T cells and the B cells. And so T cells and the B cells are going to be lymphocytes important and adaptive immunity. And that means that they are both going to respond to very, very specific antigens of invading microbes. And the specificity here is a characteristic of adaptive immunity, but once again, not all lymphocytes are part of adaptive immunity. And so what we need to uh note here is that however, there are a group of lymphocytes, specifically the innate lymphoid cells that differ from the B and T cells because the B and T cells are part of adaptive immunity. But the innate lymphoid cells are actually part of innate immunity. And so, the innate lymphoid cells are commonly abbreviated as IL CS for short innate lymphoid cells. And they differ from the B and T cells due to a lack of specificity in the antigen recognition. And so, whereas T cells and B cells are very, very specific and part of adaptive immunity. Uh the innate lymphoid cells lack specificity. And so, a classic example of Il CS or innate lymphoid cells are these natural killer cells or for short, these NK cells or NKS. And uh these natural killer cells are innate lymphoid cells and they kill a variety of different cell types. So they are not specific to one type of antigen, they are going to be uh not specific. And so uh taking a look at this image that you see over here, notice that we're focusing specifically on the lymphocytes. And once again, the lymphocytes include natural killer cells which are innate lymphoid cells that are part of innate immunity. But it also includes the T cells and the B cells, which are important for adaptive immunity and adaptive immune responses. So once again, we'll be able to talk a lot more details about the T cells and B cells later in our course, when we're talking about the adaptive immune responses, and we'll also uh while we're talking, talking about the lymphocytes at that time, we'll also be able to talk a little bit more details about the natural killer cells as well later in our course, in those separate videos. But for now, this year concludes our brief introduction to the lymphocytes. And we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.
6
Problem
Problem
Why is a bone marrow transplant used to replace defective lymphocytes in a patient?
A
Bone marrow creates common myeloid progenitor cells which differentiate into lymphocytes.
B
Bone marrow creates monocytes which differentiate into lymphocytes.
C
Bone marrow creates hematopoietic stem cells which differentiate into all immune cells including lymphocytes.
7
Problem
Problem
Which of the following immune cells is NOT a professional phagocyte?
A
NK cell.
B
Neutrophil.
C
Macrophage.
D
Dendritic cell.
8
Problem
Problem
Which of the following are referred to as mononuclear phagocytes?
A
Lymphocytes and basophils.
B
Mast cells and eosinophils.
C
Basophils and eosinophils.
D
Monocytes and macrophages.
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