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20 Cards in this Set
- Front
- Back
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Which cells are involved in the non specific immune response and what does this mean?
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Phagocytes called neutrophils and macrophages. It means that they recognise all foreign cells.
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Outline the course of events during phagocytosis.
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It seeks the non self particle.
The phagocyte membrane engulfs the particle by endocytosis. The lysosome fuses with the particle. It breaks the particle down and expells the particle by exocytosis. |
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Describe B cells
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Made in bone marrow before birth.
Each one has a different receptor for a non self antigen. Stimulated by cytokines. Divide into plasma B cells and memory cells. |
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Distinguish between plasma B cells and memory B cells.
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Plasma B cells divide by mitosis to make a clone of identical cells. They then enter the blood and make antibodies.
Memory B cells remain behind and are responsible for a greater and faster secondary immune response. |
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Describe T cells.
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Made in bone marrow but move to thymus gland before birth to mature.
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Describe the types of T cells.
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Each T cell has a receptor to fit an antigen. They circulate in the blood and when they come into contact with an antigen they activate and divide by mitosis.
Helper T cells and killer T cells are made. |
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Distinguish between helper and killer T cells.
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Helper T cells release cytokines when activated.
Killer T cells attack pathogens. |
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Explain the mode of action of Killer T cells.
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Seek pathogen.
Attach on to antigen activate T cell Puch hole in cell membrane Inject hydrogen peroxide to destroy it. |
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Explain the role of cytokines.
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These small protein particles stimulate phagocytes to work more vigorously and activate B cells in the bone marrow.
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Explain how a cell that has a non self antigen on its surface may not be a non self cell.
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When phagocytes engulf a foreign particle they may display the antigen on the surface of the cell to increase chance of actiovating helper T cell.
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Describe the structure of an antibody molecule.
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4 polypeptide chains
2 heavy 2 light held together by disulphide bridges Variable region and constant region. Hinge allows flexibility to bind with antigen. Variable region allows specificity. |
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Describe how a vaccine works.
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An injection that may contain;
isolated antigens weakened pathogen - a live vaccine a similar but less harmful pathogen. An immune response is made without the person getting sick. B and T memory cells remain behind. Next time exposed to the antigen, immune response is quicker and greater and pathogen destroyed without making person sick. |
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Explain how a vaccination program has eradivcated smallpox successfully but not measles.
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Smallpox virus antigen is stable, measles is unstable.
Smallpox passed on by direct contact, measles by droplet infection. Easy to spot someone with small pox, measles less obvious. Measles virus can remain in air 2 hours after a person sneezed. |
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Explain natural active immunity.
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Person has been exposed to antigen, been ill, and memory B cells remain behind in the lymph glands.
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Explain artificial active immunity.
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A person has been injected with a vaccine. The memory cells remain in the lymph but the person did not get sick.
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Explain natural passive immunity.
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When antobodies pass from mother to unborn child or in the breast milk in the first week of life. No B memory cells remain.
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Explain artificial passive immunity.
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A person is injected with antibodies. The immunity is short lived. Eg a snake bite will kill before you can mobilise antobodies so they are injected. No memory cells remain.
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Describe the lymphatic system.
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Oxyegen and glucose passes out of blood in tissue fluid.
The tissue fluid needs to be removed. It enters another closed system called the lymphatic system. At glands the tissue fluid (lymph) is returned to the blood. Lymph glands store memory B and T cells. |
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Explain why there isn't an effective inflenza vaccine.
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Virus is unstable.
The antigens keep changing. A vaccine becomes ineffective against a newly mutated virus. |
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Describe the mode of action of differernt antibodies.
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•agglutination makes pathogens clump together
•antitoxins neutralise the toxins produced by bacteria •lysis digests the bacterial membrane, killing the bacterium •opsonisation coats the pathogen in protein that identifies them as foreign cells. |
