Microbiology Final Test Answers – Flashcards
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| Vaccine |
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| A suspension of microorganisms or fractions of microorganisms that is used to induce immunity |
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| Why do anitigens in vaccines not cause disease? |
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| They are either killed, weakened or non-living |
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| What are the four main types of vaccinesWhat are two other types of vaccines? |
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| 1) Attenuated whole-agent 2) Inactivated whole-agent 3) Subunit 4) Toxoids Other: 1) Conjugated 2) Nucleic acid |
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| Describe an attenuated whole-agent vaccine? |
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| Uses living, but weakened microbes--weakened by serial passage through a "poor" host for the virus |
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| What are three examples of an attenuated whole-agent vaccine? |
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| 1) MMR-measles, mump and rubella 2) Oral Polio virus vaccine 3) Tuberculosis vaccine |
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| What are four advantages of an attenuated whole-agent vaccines? |
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| 1) Microbes multiply in the body 2) The original dose is increased with time, acting as a series of secondary immunizations 3) Generally provides strong and long lasting immunity 4) Immunizes contacts, good for the entire population |
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| What are two disadvantages of an attenuated whole-agent vaccines? |
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| 1) Not recommended for immunosuppressed people 2) Microbes can back mutate to a more virulent form |
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| Describe inactivated whole-agent vaccine. |
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| Uses microbes that are "killed" by chemical (usually with formalin or phenol) or physical treatment |
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| Give three examples of inactivated whole-agent vaccine. |
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| 1) Influenza 2) Inactivated Polio virus vaccine 3) Rabies |
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| What are two advantages of inactivated whole-agent vaccines? |
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| 1) Not disease-causing because microbes are non-living 2) Cannot harm immunosuppressed people |
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| What are three disadvantages of inactivated whole-agent vaccines? |
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| 1) Antigen dose doesn't increase in the host since microbes cannot multiply 2) Short-lived immunity, immunity is not as strong as with attenuated whole-agent vaccines 3) Doesn't immunize contacts, not good for the entire population |
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| Describe a subunit vaccine. |
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| Contain only part of a microorganism that best stimulate an immune response, such as a bacterial cell wall, capsule components, viral coat or envelope |
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| What are the two basic types of subunit vaccines? |
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| 1) Capsular: use bacterial capsular proteins 2) Recombinant: use viral proteins that are made by genetic engineering |
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| What is an advantage of subunit vaccines? |
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| Not disease-causing, microbes are non-living |
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| What is a disadvantage of subunit vaccines? |
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| Weaker immune response |
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| What are two examples of a subunit vaccine? |
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| 1) Hepatitis B 2) Pneumococcal pneumonia |
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| Describe a toxoid vaccine. |
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| A bacterial toxin that is inactivated with chemicals without altering its antigenic properties. Produces antibodies that can bind to the toxoid and that actual toxin. The neutralizes the toxin by stopping attachment to the host cells. |
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| What are two examples of toxoid vaccines? |
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| 1) Tetanus toxoid 2) Diphtheria toxoid |
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| What are three advantages of toxoid vaccines? |
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| 1) Stimulate strong antibody production 2) Produce long-lasting memory cells 3) Toxoid cannot cause any disease |
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| What are two disadvantages of toxoid vaccines? |
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| 1) Require series of injections 2) Require boosters every 10 years |
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| What are four characteristics of conjugated vaccines? |
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| 1) This has been developed to deal with poor immune response of children to vaccines based on capsular polysaccharides. 2) Polysaccharides are T-independent antigens. 3) Children's immune system do not respond to these antigens until the age 15-24 months 4) Polysaccharides are combined with proteins such as diphtheria toxoid |
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| What is an example of a conjugated vaccine? |
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| Hib vaccine: capsular polysaccharides and diphtheria toxoid together to enhance immune response; provides significant protection even at 2 months of age |
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| What are three characteristics of nucleic acid vaccines? |
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| 1) DNA vaccines are among the newest and most promising vaccines 2) There aren't any commercial DNA vaccines for humans 3) DNA remain efficient only until it is degraded |
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| Innate immunity |
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| Defenses against any pathogen Immunity you are born with |
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| Immunity |
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| Specific antibody and lymphocyte response to an antigen |
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| Antigen (Ag) |
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| A substance that causes the body to produce specific antibodies or sensitized T cells |
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| Antibody (Ab) |
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| Proteins made in response to an antigen |
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| Serology |
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| Study of reactions between antibodies and antigens |
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| Antiserum |
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| Generic term for serum because it contains antibodies |
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| Globulins |
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| serum proteins |
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| Gamma globulin |
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| Serum fraction containing Ab |
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| Acquired immunity |
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| Developed during an individual's lifetime |
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| Humoral immunity |
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| Antibody-mediated immunity Involves Ab produced by B cells |
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| Cell-mediated immunity |
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| Involves T cells |
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| Immunity resulting from infection; when a person gets sick |
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| Naturally acquired active immunity |
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| Immunity acquired transplacental or via colustrum (when a fetus or infant gets immunity from mother) |
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| Naturally acquired passive immunity |
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| Immunity acquired from the injection of Ag (vaccination or immunization) |
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| Artificially acquired active immunity |
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| Immunity acquired from the injection of Ab or serum globulins |
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| Artificially acquired passive immunity |
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| Haptens |
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| 1) Hapten molecule and carrier molecule together make the complete antigen 2) Hapten molecules are too small to stimulate antibody formation, but with carrier molecules they form larger antigens that can stimulate antibody response |
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| Five characteristics of antibodies. |
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| 1) Antibodies have a "Y" shape 2) Antibody is made up of heavy chains and light chains 3) Di-sulfide bonds link different regions together 4) An antibody has a constant region (c) and a variable region (v) 5) Antigens attach to the variable region of the antibody molecule |
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| What are the five classes of immunoglobulins (antibodies)? |
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| 1) IgG 2) IgM 3) IgA 4) IgD 5) IgE |
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| Which antibody is the most abundant in serum? |
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| IgG |
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| What antibody is the most abundant in our body? |
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| IgA |
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| Which antibody is the least abundant in the body? |
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| IgE |
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| Which antibodies are monomers? |
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| IgG, IgD, IgE |
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| Which antibodies are dimers? |
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| IgA |
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| What antibodies are pentamers? |
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| IgM |
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| Which antibody is found in mucus, saliva and tears? |
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| IgA |
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| Which antibody is found on B cells? |
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| IgD |
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| What antibody can fix complement? |
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| IgG |
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| Which antibody can agglutinate antigens? |
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| IgM |
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| Presence of which antibody indicates a current infection? |
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| IgM |
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| Describe B cell clonal selection. |
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| When a B cell recognizes and binds to the specific antigen; B cell proliferates into a large clone of cells; in other words, B cell makes large number of similar B cells |
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| Differentiation of B cells |
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| Some B cells differentiate into long-lived memory cells and remain in the body for ever; Some B cells differentiate into plasma cells |
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| Self-tolerance |
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| Body doesn't make antibodies against it's own self cells. The immune system can differentiate between self and nonself. |
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| Clonal deletion in relation to our immune system |
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| Process of destroying B and T cells that react to self-antigens |
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| Apoptosis |
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| Programmed cell death; human body makes about 100 million lymphocytes each day so an equal number must die |
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| What are the six ways Ag-Ab binding helps stop pathogenic bateria from causing disease? |
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| 1) Agglutination 2) Opsonization 3) Neutralization 4) Activation of complement 5) Inflammation 6) Antibody dependent cell-mediated cytotoxicity |
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| Agglutination |
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| enhance phagocytosis by decreasing the number of infectious units |
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| Opsonization |
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| Immune adherence: enhance phagocytosis by coating antigen with antibody |
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| Neutralization |
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| block attachment of bacteria and viruses to the mucosal membranes; block active site of toxins |
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| Activation of complement |
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| Attract complement to the surface of bacteria, this leads to cell lysis or cytolysis |
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| Inflammation |
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| disruption of cells by complement attract phagocytes and other immune system cells |
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| Antibody dependent cell-mediated cytotoxicity |
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| enhance the activity of non-specific immune system cells; NK cells and neutrophils |
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| What are cytokines? |
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| The chemical messengers of immune cells |
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| What are interleukins? |
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| Cytokines that act as communicators between leukocytes |
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| What are antigen presenting cells? |
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| Dendritic cells, abundant in the skin and mucous membranes, that ingest and process the antigen and display fragments of the antigen on the surface |
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| What are the four types of T cells? |
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| 1) Helper T cells 2) Cytotoxic T cells 3) Delayed Hypersensitivity T cells 4) Suppressor T cells |
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| Helper T cells |
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| Activate cells related to cell-mediated immunity Activate B cells |
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| Cytotoxic T cells |
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| Releasing a protein called perforin Forms a pore in the membrane causing the infected cell to lyse |
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| Delayed Hypersensitivity T cells |
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| Associated with allergic reaction, transplant rejection, reaction to poison ivy and tuberculin skin test |
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| Suppressor T cells |
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| Turn off immune response when antigen is no longer present |
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| Describe T-dependent antigens and give an example |
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| Requires the assistance of helper T cells to produce antibodies; proteins found on viruses and bacteria |
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| Describe T-independent antigens and give an example |
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| Antigens that stimulate the B cells to make antibodies without the aid of helper T cells; polysaccharides of the bacterial capsule |
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| Susceptibility |
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| Lack of resistance to a disease |
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| Resistance |
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| Ability to ward off disease |
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| Non-specific resistance |
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| Defenses against any pathogen |
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| Specific resistance |
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| Immunity to a specific pathogen |
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| First line of defense |
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| 1) Skin (dermis and epidermis): mechanical and chemical 2) Mucous membranes: mechanical and chemical 3) Normal microbiota |
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| What are some examples of mechanical muscous membrane defenses? |
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| 1) Mucus: microbes trapped in mucus are transported away from the lungs 2) Lacrimal apparatus: washes eye 3) Saliva: washes microbes off 4) Ciliary escalator: cilia propel microbes trapped in mucus toward the throat |
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| What are some chemical examples of defense? |
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| 1) Sebum: fatty acids inhibit the growth of bacteria and fungi; low pH of skin 2) Lysozyme in fluids break the chemical bonds on peptidoglycan 3) Low pH of stomach acid 4) Transferrins (iron binding protein) in blood |
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| How do normal microbiota act as a defense? |
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| Microbial antagonism or competitive exclusion; inhabit all possible niches of the human body and compete with pathogens for habitat and available nutrients |
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| What is phagocytosis? Explain how it relates to human defenses against pathogenic microbes. |
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| The ingestion of microbes or particles by a cell Phagocytes ingest invading microbes to digest and neutrolize them |
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| What are the four stages of phagocytosis? |
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| 1) Chemotaxis 2) Adherence 3) Ingestion 4) Digestion |
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| Chemotaxis |
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| chemical attraction |
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| Adherence |
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| attachment to the plasma membrane of the phagocyte |
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| Ingestion |
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| with the help of pseudopods and form phagosomes (phagocytic vesicles) |
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| Digestion |
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| 1) Phagosome enters the cytoplasm, meet with lysosomes forming phagolysosome 2) Lysozyme and other enzymes hydrolyse the bacterial components 3) Lysosomes produce toxic oxygen products by a process called "oxidative burst" 4) Residual body is discharged from the cell |
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| What are the two main types of white blood cells that perform phagocytosis in the human body? |
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| 1) Neutrophils 2) Macrophages? |
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| Phagocytosis comes under which line of defense? |
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| Second |
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| Give two examples of microbial evasion of phagocytosis. |
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| 1) Escape phagosome: Shigella 2) Prevent phagosome-lysosome fusion:HIV 3) Survive in phagolysosome: Coxiella burnetti |
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| What is inflammation? |
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| Defensive response to the damaged body tissues |
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| What are five signs of inflammation? |
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| 1) Redness 2) Pain 3) Heat 4) Swelling (edema) 5) Loss of function |
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| Inflammation comes under which line of defense? |
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| Second |
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| What are the three functions of inflammation? |
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| 1) Destroy the agent causing the disease 2) Limit the effect 3) Repair |
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| What are the three stages of inflammation? |
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| 1) Vasodilation 2) Phagocyte migration and phagocytosis 3) Tissue repair |
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| Three functions of vasodilation |
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| 1) Increase blood flow to the damaged area cause redness (erythema), heat and pain 2) Blood clots prevent the microbe from spreading 3) Localize collection of pus and dead cells (abcess) |
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| Four characteristics of phagocyte migration and phagocytosis. |
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| 1) Phagocytes appear on the scene within an hour 2) Phagocytes begin to stick to the lining of blood vessels (margination) 3) Phagocytes squeeze between the blood vessel cells and reach the damaged area (emigration or diapedesis) 4) Phagocytes begin to destroy the invading microbes |
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| Three characteristics of tissue repair. |
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| Epidermis or dermis produces new cells 1) Depends on the type of tissue: skin-regenerate faster heart muscle-does not regenerate 2) Tissue is repaired when epidermis or dermis produces new cells 3) If dermal cells are more active than the epidermal cells, scar tissue is formed |
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| What are the four chemicals released by damaged cells that are responsible for vasodilation? |
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| 1) Histamine 2) Kinins 3) Prostaglandins 4) Leukotrienes |
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| What is margination? |
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| Phagocytes begin to stick to the lining of blood vessels |
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| What is emigration (diapedesis)? |
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| Phagocytes squeeze between the blood vessel cells and reach the damaged area |
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| Chills and shivering is a sign that? |
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| 1) Body has increased rate of metabolism to raise temperature 2) Gram-negative endotoxin causes release of interleukin-I |
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| Crisis and sweating is a sign that? |
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| IL-1 is eliminated body temperature falls |
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| Fixed macrophages (histiocytes) |
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| Found in lungs, liver, bronchi, nervous system, spleen, lymph nodes, bone marrow |
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| Wandering macrophages |
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| roam tissues; gather at sites of infection |
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| What are five conditions in which phagocytosis can be less effective? |
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| 1) Born with an inability to produce phagocytes 2) Progressive decline with age 3) Recipients of heart and kidney transplants 4) Radiation treatments 5) Aids and cancer patients |
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| Name an antimicrobial substance that is involved in our second line of defense and how does it work. |
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| Gamma interferon: causes neutrophils and macrophages to phagocyte bacteria |
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| Describe the complement system |
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| Over 30 proteins produced by liver and found circulating in the blood serum; number C1-C9, serum proteins are activated in a cascade, for example C5-C9 cause cytolysis |
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| Three characteristics of complement system |
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| Opsonization or immune adherence: enhanced phagocytosis Membrane attack complex (MAC): cytolysis Attract phagocytes |
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| Three ways bacteria evade complement. |
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| 1) Capsules prevent Complement activation 2) Surface lipid-carbohydrates prevent MAC formation 3) Enzymatic digestion of complement proteins |
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| Interferons are produced... |
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| after viral infections by fibroblasts (found in the connective tissues) and leukocytes |
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| Three characteristics of interferons. |
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| 1) Small proteins 2) Interfere with viral multiplication 3) Host cell specific but not virus specific |
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| What are the three principal types of human interferons? |
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| 1) Alpha IFN 2) Beta IFN 3) Gamma IFN |
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| Alpha IFN and Beta IFN |
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| cause cells to produce antiviral proteins that inhibit viral replication; produced by the virus infected cells |
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| Gamma IFN |
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| Causes neutrophils and macrophages to phagocyte bacteria; produced by lymphocytes |
