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29 Cards in this Set
- Front
- Back
What is specific immunity?
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Specific Immunity
-When the non-specific defense fails, then the third, specific line of immunity is activated -Immunity is not innate but adaptive; it is acquired over time -It is characterized with a specificity and memory -Specificity – antibodies against chickenpox is not effective against measles virus -During the 2nd encounter with a pathogen, the lymphocytes recall the 1st engagement and attacks it again |
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What is immunity?
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immunity is a defensive responses of the body when a foreign organism or foreign substance invades it
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What are antigens and antibodies?
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-Antigens are substances (proteins or polysaccharides) that provoke immune response
-Antibodies are proteins produced to inactivate the antigens -During the immune response, lymphocytes organize and bind to the antigen |
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What are the two components of the immune system?
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-Humoral immunity – production of antibodies (B-cells)
-Cell-mediated immunity – activation and proliferation of immune system cells (T-cells) |
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What are the 5 stages of lymphocyte development and interaction?
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There are 5 stages:
1. Development of B-cells and T-Cells 2. Antigen presenting cells present the antigen to lymphocytes 3. Lymphocytes proliferate – produce responder cells and memory cells 4. B lymphocytes become plasma cells – produce antibodies 5. Activated T-cells become Helper T cells and cytotoxic T cells |
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Describe the Specificity of the lymphocytes.
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-They have receptor sites on the cell surface that can recognize millions of different antigens
-This great diversity of receptor sites is achieved through genetic recombination of 500 genes -The lymphocytes with the receptor sites for “self” cells are eliminated -Upon entry of an antigen, only lymphocytes specific to that antigen proliferate – clonal selection |
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What are the characteristics of antigens?
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Not a normal constituent of the body
-They are components of microbial cells (capsule, cell wall, flagella, fimbriae, microbial toxins, and coats of viruses), humans, plants, animals -They belong to: proteins, lipoproteins, glycoproteins -Good antigens have complex molecules -Poor antigens have small and simple molecules -Antigens contain specific regions that are recognized by antibodies – antigenic determinants or epitopes |
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What are superantigens?
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-Superantigens (bacterial toxins) can trigger a 100 times greater response of immune system – toxic shock syndrome
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How are antigents processed ans presented?
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-Antigens are presented to lymphocytes by antigen- presenting cells (APCs) – macrophages, B cells, dendritic cells
-APC ingests the bacterial cell – degrade the antigen into smaller peptides -Complexed with a cell glycoprotein (MHCII) and transported to the cell surface -MHCII (major histocompatibility complex) – function in a recognition of self -The antigen complexed with MNCII is presented to T helper cells -T cells are activated – they release interleukin-2 -Assists with B cell system |
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What stimulates the B-cells?
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-The linked receptor of T-cells and B-cells, and chemical stimulus from the T-cell – stimulates the B-cells
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What two types of cells are formed in B-cell activation and antibody synthesis?
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-Two types of cells are formed: memory cells and plasma cells
-Memory cells play role in future exposure to the same antigen -Plasma cells – synthesize and release the antibodies |
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what are antibodies?
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-Antibodies are specific proteins (immunoglobulins – lg) developed by the body that is invaded by a specific microorganism
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what is the structure of an antibody?
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-The antibody molecule is Y-shaped. It consists of 4 protein chains:
- 2 identical heavy chains - 2 identical light chains -Each antibody molecule has two binding sites (site that binds to antigen) -Antibody molecule is made up of -constant region -variable region: binds the epitope of the antigen |
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How do antibodies and antigens interact?
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Antibody-Antigen Interactions
-Complementary fit between antigen and antibody is needed -The better the fit the better the stimulation of lymphocytes |
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How are antigens rendered harmless?
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-Antigens are rendered harmless by different mechanisms
-Agglutination – antibodies cross-link the antigens (bacterial cells) forming aggregates that are more easily digested by phagocytes -Opsonization- antibodies coat the antigens enhancing the phagocytosis -Neutralization – antibodies block the active sites of viruses preventing their attachment to host cells |
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What are the 5 immuoglobulin classes?
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IgG- 80% of all antibodies; effect against bacteria, toxin, trigger the complement system, long term immunity
-IgA- abundant in mucus membrane -IgM- Large molecule, first to appear, circulate in blood -IgD – small amounts (1%) has no well-defined function, B-cell activation -IgE- play role in allergic reaction *IGAMED* |
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what is the primary response to antigens?
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Primary response
-There s a latent period -Takes longer to reach the maximum |
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What is the secondary respond to antigens
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Secondary response
-Memory cells responsible -Fast response -Higher concentration of immunoglobulins -Basis for vaccination |
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What are T-cells?
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-Produced in the bone marrow, mature in the thymus gland, and wait for the encounter with antigens in the lymphoid organs
Two populations of T-cells: -Helper T-cells (with CD4 receptor) -Recognize peptides that are presented on dendritic cells -Cytotoxic T cells |
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What are the helper t cells?
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-Activation helper cells produce cytokins – Th cells proliferate and produce
-Cytotoxic T cells -natural killer cells -macrophages -Depression of T cell (class CD4) by HIV is responsible for pathology of AIDS |
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What are cytotoxic t cells?
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Cytotoxic T Cells
-Recognize and kill the infected cell (some microorganisms multiple inside the host ell) -Recognizes and kill nonself (tumor) cells -Attaches to the target and releases perforin (pore-forming protein) |
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what are natural killers cells?
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Natural Killer Cells
-Lymphocytes related to T cells -They do not have specificity for antigen -The first to attack cancer cells and virus infected cells |
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What are the types of specfic immunity?
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Natural active immunity
-Getting the infection -Natural passive immunity -Maternal antibodies are transported across placenta -Artificial Active Immunity -Vaccination -Artificial Passive Immunity (immunotherapy) -Administration of specific antibody-obtained by vaccinating animals and extracting the serum |
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What is the technique of Monoclonal Antibodies?
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-Technique by which large amounts of specific antibodies can be produced
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What are vaccines?
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-Vaccine is a suspension of microorganisms or their cell components that are injected into a human or animal body in order to induce immunity
-The purpose of vaccination is to control microbial diseases and to prevent epidemics |
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what are the types of vaccines?
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Attenuated whole agent vaccine
-Use of living but attenuated (weakened) or mutant microbe. Measles, mumps, rubella (MMR) -Advantage: more closely mimic an actual infection -Disadvantage: can backmutate to virulent form and cause a disease Inactivated whole-agent vaccines -Use of killed microbes (rabies, influenza, and polio) -Killed by formalin or phenol Toxoids -Chemically or thermally modified toxins used to stimulate active immunity -Tetanus, diphtheria toxoids – requires series of injections -Require boosters every 10 years |
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What are recombinant vaccines?
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-Genetically engineered microorganisms produce the antigenic fraction of the pathogen (Hepatitis B).
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What is DNA vaccine?
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Promising technology in vaccine production
-Gene coding for an antigen is incorporated into a plasmid – “naked” DNA (plasmid) injected -Human cells will take up the plasmid -Foreign protein (antigen) will be expressed, this will stimulate immune response |
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Why are vaccinations important?
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-To protect individuals
-To establish herd immunity -Protection of the whole population -Prevention of epidemics -Protection of non-immunized individuals |