Nonspecific host resistance and the immune response – Flashcards
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| Resistance |
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| ability to fight off a disease |
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| Susceptibility |
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| lack of resistance |
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| Antigen |
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| any substance self or foreign that can initiate an immune response to an immune competent host |
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| T-dependent antigen |
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| an antigen that requires assistance from T-helper lymphocytes to synthesize antibodies |
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| T-independent antigen |
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| an antigen that does not require assistance from T-helper lymphocytes to synthesize antibodies |
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| Hapten |
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| an incomplete antigen; an antigen that cannot initiate or trigger an immune response on its own |
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| Antibody |
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| a specific protein synthesized in response to a specific antigen |
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| B-lymphocytes/ B-cells |
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| provide humoral immunity by synthesizing antibodies |
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| T-lymphocytes/ T-cells |
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| provide cellular immunity by synthesizing group of proteins called lymphokines |
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| Vaccine |
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| an antigen that protects the host from a specific disease |
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| Opsonin |
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| any substance that increases the chance of phagocytosis |
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| Nonspecific defense of the host (first line of defense) A. Constitutional factors: 1.species resistance: |
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| a. Birds are resistant to B.anthracis, while cattle are susceptible b. humans get mumps but cats and dogs do not c. Humans are susceptible to plaque (Yersinia pestis) while groung squirrels are resistant |
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| 2. Race or strain resistance |
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| a. African blacks are more susceptible to tb and malaria than whites b. whites are more susceptible to influenza, diphtheria, and gonorrhea than blacks |
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| 3. Gender (male or female) |
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| female mice were 20% more resistant to typhoid fever than male mice |
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| 4. Nutrition |
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| dietary protein and vitamins are directly related to protection from microbial disease. Proteins are used to make healthy new tissues and serum proteins, while vitamins are essential for various metabolic activities Cabbage--> susceptibility to salmonella reduced |
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| 5. Age |
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| very young ( have not developed immunity Igg) and very old (size of thymus shrinks) are more susceptible to disease |
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| B. Physical and Chemical factors: 1. Skin |
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| a. low moisture (fungus) b. lactic acid c. low pH (3-5) d. lysosyme (G+ bacterial growth protection(sweat glands) and sebum (sebaceous glands) |
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| 2. Mucus membrane |
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| it covers the entire digestive, respiratory, and reproductive tracts Mucus membrane (goblet cells) v mucus + cilia v throat v v Stomach (pH 1.5-2.5)out (cough/sneeze) |
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| Which pathogenic organisms can penetrate through healthy mucus membrane and cause disease? |
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| 1. Treponema pallidun 2. Mycobacterium tuberculosis 3. Streptococcus pneumoniae |
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| C. Cellular factors 1. Inflammation 2. Phagocytosis |
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| ( leak of fluirds) a process of vasodilation caused by bradykinin which triggers mast cells to release histamine. Histamine is a vasodilator. |
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| Phagocytic cells: 1.Wandering phagocytic cells |
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| a. lymphocytes b. monocytes c. neutrophils |
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| 2. Fixed phagocytic cells (histiocytes) *** |
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| a.Kupffer's cells: found in liver and spleen (after 120 days go to liver and turn into biliruben) b. Alveolar macrophages: found in lungs c. Microglial celss of CNS |
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| Steps of phagocytosis?*** |
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| 1.chemotaxis or adherence (attachment) 2.ingestion (by means of phagosome) 3.intracellular digestion 4.exocytosis (release of microbial debris) |
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| 3. Natural killer cells |
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| 1. adherence 2. ingestion (psudopodium) 3. formation of phagosome 4. lysosome ->fusion 5. phagolysosome 6. destruction of microbes, release of microbial debris |
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| D. Microbial factors |
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| Normal flora competes with pathogenic intruders for food and space Ex: E.coli (lg instestine) Lactobacillus (vagina) |
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| Specific defenses of the host (second line of defense) The immune response (antibody+antigen) A. Actively acquired |
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| host makes his/her own antibodies(long term) 1. Natural: host comes in contact with unintentional exposure to antigen and produces his/her antibodies 2.artificial- giving antigen intentionally, same as vaccine (long term) |
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| B. Passively acquired |
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| someone else makes the antibodies for a host (short term immunity) 1.natural- mom to fetus 2.artificial- horse to a baby |
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| The duality of immune system: A. the humoral (antibody-mediated immune response) |
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| -protects host at body fld level (blood plasma, lymph, mucus, and other body secretions) -only B-cells are directly involved, which produce antibodies -Effective mostly against bacteria, bacterial toxins and viruses |
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| B.The cell immediate immune system |
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| -active at cellular and blood level -T-cells are involved which produce lymphokines (a group of proteins that regulate the activities of other cells) -antibodies are not involved -effective mostly against intracellular bacteria, virus and fungi |
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| Characteristics of antigen or immunogen |
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| 1. should have molecular wt of 10,000 Daltons or more 2. should be solubilized by body enzymes (ex.pneumococcal antigen is more antigenic in mice than in man) 3. foreigness: must possess nonself epitopes (specific area to which an antibody attaches) 4. Molecular complexity |
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| Antigen elimination curve: |
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| 1. 90% of the antigen is removed withing 10-20 minutes by phagocytosis 2. long catabolic phase 3. remaining antigen molecules are opsonized and eventually phagocytized |
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| B and T-lymphocyte production |
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| Bone marrow (multipotent stem cell/hemocytoblast) v rubriblast (RBC) myaloblast (granulocytes) monoblast (monocyte) megakaryoblast (thrombocytes) Lymphoblast v v Thymus Galt v v T-lymphocyte v (gut associated lymphoid tissues: spleen, appendix, lymph nodes, Pyer's Patches) v B-Lymphocyte |
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| Function of B-lymphocytes? |
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| provide humoral immunity by making antibodies |
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| Function of T-lymphocytes? |
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| provide cellular immunity |
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| The antibody response |
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| A. Microbial antigen is processed by a phagocytic cell B. Antigen is presented on the surface of phagocytic cell, now called Antigen Presenting Cell (APC) C. Stimulation of a B-lymphocyte by an APC results in the production of plasma cells (produce antibodies during primary response) and memory cells (produce antibodies during secondary response) |
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| Function of Thymus gland? |
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| where T-lymphocytes mature |
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| What is the purpose of booster shot? |
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| to enhance number of memory cells |
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| ***Primary immune response: |
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| 1. Long catabolic phase/processing 2. low abtibody titer 3. Lesser avidity towards antigen (not strong bonding) 4. Antibodies are mostly IgM 5. Decrease in antibody titer is rapid |
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| ***Secondary or booster or anamnestic immune response: |
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| 1. short catabolic phase 2. high antibody titer 3. higher avidity towards antigen 4. Antibodies are mostly IgG (immunoglobulin) 5. Decrease in antibody titer is gradual |
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| Structure of antibody: |
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| -antibodies belong to a class of proteins called immunoglobulin (IgG) -an antibody resembles the letter Y, which is made of four polypeptide chains- two heavy (H) and two light (L) chains - The chains are joined together by disulfide bonds (2) - Most of the antibody molecules is made up of a constant (C) regions, which are the same for all antibodies of the same class -Both the H and L have sections located at the end of Y's arm called (V) regions which bind to specific antigens |
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| Class 1: IgG |
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| A. most common antibody in human serum B. found in blood, lymph and intestine C. protect against circulating bacteria, viruses, neutralize bacterial toxins, and enhance phagocytic activity D. protect fetus and the new born E. appears in second immune response |
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| Class 2: IgM |
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| A. found in blood and lymph B. first to appear after antigenic stimulation C. protects fetus and newborn, but cannot be transferred from mother to fetus through placenta |
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| ***Class 3: IgA (highest in body flds) |
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| A. Found in body secretions such as tears, mucus, saliva, colostrum, and lymph |
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| Class 4: IgD |
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| A. Found in blood and lymph B. function unknown |
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| ***Class 5: IgE (bad for ppl, high level ppl keep epinephrine pen) |
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| A. Found in blood (surface of mast cells) B. Responsible for hypertensive response (mast cell->final destination->inflammation) |
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| Hypertensive allergic reaction: 1. T-helper or inducer cells (Th, T4) |
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| -assist T-dependent antigen to produce antibodies |
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| 2. T-suppressor cells (Ts, T8) |
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| -stop antibody production |
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| 3. Cytotoxic killer cells (Tk, TctL) |
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| -destroy cancerous, tumor, and cells invaded by microorganisms; also responsible for graft rejection |
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| 4. Delayed hypersensitivity T-cells (Td) (delayed allergies) |
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| -responsible for allergies occurring several hours or days after contact; skin reactions as in tuberculin test |
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| Autoimmune diseases (humoral or cell medicated response against self-antigen) |
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| A. Grave's disease B. Rheumatoid arthritis C. Systemic lupus erythematosus |
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| Grave's disease: |
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| excessive thyroid hormone production when antibodies react with thyroid gland Anti-thyroid |
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| Rheumatoid arthritis: |
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| anti-chondrocytic antibodies |
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| Systemic lupus erythematosus |
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| anti-nuclear antibodies |
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| B-cell deficiencies |
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| Bruton's agammaglobulinemia (body cannot produce any antibodies at all) |
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| T-cell deficiencies: |
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| A. AIDS B. Nezelof's syndrome |
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| AIDS |
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| T-4 cells |
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| Nezelof's syndrome |
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| babies born without thymus |
