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  • >>Dr. Ketchum: Now were going to start the immune system. And so what I want you

  • to think about first off is, “Well what is immunity?” So humans demonstrate immunity

  • by possessing tissues that are capable of recognizing and protecting them against non-self

  • invaders. Short and sweetyour immune system is there to defend your body from foreign

  • invaders. Those foreign invaders come in all shapes and sizes and varieties. So let’s

  • look at what the targets are for the immune system. In other words, who are the foreign

  • invaders? Some of the targets are pathogens, and these pathogens can be viral, bacterial,

  • like staphylococcus. They can be actual parasites, like for example tapeworms, roundworms. The

  • targets may be fungi or even protozoa, which some of you may be more familiar with protist.

  • Protist is a newer term that were using these days.

  • Now there are also other targets for your immune system. So worn out cells. As cells

  • in our body start to wear out and die, they are now targets for the immune system. Because

  • when it’s wearing out and dying, it’s more likely to start dysfunctioning and can

  • result in cancerous cells, can cause tumors, and all sorts of things. So you want to kill

  • the worn out, dying cells. The other thing that the immune system is going to target

  • are mutant cells. These are abnormal cells in the body, and then also cellular debris.

  • So when you think about cellular debris, think in terms of if youre going to break down

  • a cell and the debris that’s associated with that cell once it’s broken down. Okay,

  • so let’s take a look at some of these pathogens here. So we have bacillusthis is a bacteria.

  • And these are just examples, so you do not have to memorize these. Fasciola, these are

  • some flukes, these are flatworms that you might inquire by eating undercooked fish for

  • example. This taenia solium, which is a tapeworm, and specifically this is called

  • a pork tapeworm because you will become infected with a pork tapeworm if you eat undercooked

  • pork; so it’s really important to cook your meat thoroughly. There’s also a tapeworm

  • called the beef tapeworm. And the beef tapeworm you get from eating undercooked beef. So for

  • those of you that eat your steak rare? Careful, beef tapeworms can reside in your small intestine

  • for quite some time, and then when they die, then the entire tapeworm can be released all

  • at once when they die. And they can be up to eight, 10, 20 feet long, okay? So beef

  • tapeworms are really long.

  • Then there’s trichomonas vaginalistrichomonas vaginalis. So this is a protist, and based

  • on the name you would think that this pathogen only affects females. That’s not true. Men

  • can actually get trichomonas vaginalis by coming into contact with females. So during

  • sexual contactso trichomonas vaginalis is actually considered a sexually-transmitted

  • disease, an STD; so men can get trichomonas vaginalis. Then there’s clostridium difficille.

  • Clostridium difficile is a bacteria that literally wreaks havoc in nursering homes, and what it

  • does to the elderly is it gives them profuse diarrhea, and, and the diarrhea is so watery

  • that the elderly people tend to dehydrate very quickly and sometimes they do succumb

  • to a clostridium difficile infection. Then there’s giardia. Giardia is the cutest little

  • parasite on the planet. So when you look at this little guy here, he looks like a happy

  • little thing. He looks like he’s smiling and like he’s got big old glasses on like

  • Steve Erkle or something. This protozoaand this one wont kill youbut this is what

  • you callBeaver Fever.” So if you drink contaminated water that a beaver has pooped

  • in, the beaver pooped giardia into the water and now you drink the water. So if you like

  • to go hiking and camping then it’s a really good idea to filter your pond water.

  • All right, then there’s plasmodium. Plasmodium is the protist that causes malaria, and I

  • know a lot of you have heard about malaria and how many children that it kills every

  • minute of the day. And malaria is the number one killer of children and adults in terms

  • of arthropod vector-born diseases.

  • So those are the examples of just various targets for the immune system. We have

  • all of these cells, then, in our body that have to amount an immune response. And here’s

  • the anatomy of the immune system. Were going to break this down into two components:

  • the leukocytes, those are white blood cells that specialize in the immune function, and

  • then there are the lymphoid tissues. You have different types of lymphoid tissuesthe

  • central and peripheral. So these are both what we call SDLs, and these are self-directed

  • learning. So you can imagine that as if this information were in your workbook and you

  • were filling this in in your workbook. So for example when we look at the phagocytes, I’ve

  • shown the phagocytes here for you. Neutrophils function as phagocytes. These are types of

  • leukocytes. Monocytes are found in the blood, and when they move into the tissue we change

  • their name, and now we call them a macrophage. And then the cell in the middle is called

  • the dendritic cell. Look at it; it looks like it’s got dendrites on it, right? So these

  • are all phagocytes. All of these will phagocytose foreign material. So I’ve left you a question

  • here that says, “What are the four fixed macrophages and where are they found?” I’m

  • going to give you one of them, the microglia, just to give you a starter on that question.

  • Now the other cells that are very important in mounting the immune response are the lymphocytes.

  • So again, these are also white blood cells, and there’s various types of lymphocytes

  • that were going to discuss in detail later. But to get you started on lymphocytes, I’ve

  • got a question here that says, “Most null cells”—so you need to figure out what

  • a null cell is—“these are considered natural killer cells.”

  • So we abbreviate natural killer cells NK and then cells. Those

  • are very important in fighting certain kind of infections. Are they bacterial or are they

  • viral? So I’ll let you finish filling out that fill in the blank there.

  • Now the mast cells and dendritic cells are also self-directed learning. So the question

  • there for you to answer is where are the mast cells foundwhat do they secrete? What is

  • the function of a dendritic cell, and what are the four types? Okay, then you have other

  • leukocytes that are important in secreting chemicals. For example: eosinophils. So when

  • you think about eosinophils, these are white blood cells that are really important in allergic

  • reactions, but theyre also very important in that they secrete chemicals that will dissolve

  • or kill parasites. So from before when I mentioned that you could have a tapeworm that's eight, 10,

  • 12, 20 feet long, there’s no way for an eosinophil to engulf a worm of that size. And so rather

  • than engulf it, eosinophils can actually secrete these chemicals that dissolve them. Then there

  • are other leukocytes called basophils that release some chemicals as well. Basophils

  • can release histamine, and histamine, if you remember, is it a vasodialator or vasoconstrictor?

  • It’s a vasodialator, and basophils will also secrete heparin. Heparin is an anticoagulant

  • or used as a blood thinner. So if you have a blood clot, they would put you on heparin

  • treatment and what that would do is prevent further clotting, and it would also help break

  • up that clot. Then we have the lymphoid tissues the central lymphoid tissues and the

  • peripheral lymphoid tissues. So what I want you to do is to make a list. What are the

  • central lymphoid tissues? And I’ll give you an idea hereyou should be listing two

  • of them. And then the peripheral lymphoid tissuesyou should be listing six of these.

  • And then what I want to know is what’s the connection between these central lymphoid

  • tissues and the peripheral lymphoid tissues? So in other words, when you have lymphocytes

  • in the central lymphoid tissue, do they always stay there or do they migrate out? Then you

  • guys can complete these questions down below as well.

>>Dr. Ketchum: Now were going to start the immune system. And so what I want you

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Human Phtsiology - Introduction to the Immune System

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    SylviaQQ   に公開 2015 年 09 月 12 日
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