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24 Cards in this Set
- Front
- Back
Viruses
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- consist mainly of nucleic acids
- sometimes protein shell called capsid - enter cells and divert the processes of those cells towards their own replication |
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Chlamydia
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-enter and multiply within living cell
- have morphology and life history so more complicated than viruses |
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Parasites
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- organism that grows feeds and is sheltered by a host organism
- gives no benefit to the host |
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Bacteria
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- prokaryotes that have a rigid cell wall that defines shape
- circular chromosome - reproduce with binary fission |
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Mycoplams
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-similar to bacteria except no cell wall
-more delicate than bacteria |
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Some mechanical barriers involved in the host defence
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- Skin
- Saliva - Mucous - Tears - Hair - Sweat |
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Colonization
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The act of microorganisms entering, establishing themselves and multiplying.
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Contamination
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Bacteria are present in the system but have not established or multiplied.
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Clinical Infection
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Colonization with symptoms that have a negative effect to the host.
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Sub-Clinical Infection
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Contagious, but without noticeable symptoms.
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Adherence
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- prerequisite for infection process to start
- microorganisms use physical features such as pilli capsules and enzymes |
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Toxigenicity
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Ability to make toxins the more able to make toxins a pathogen is the more virulent it is and therefore more dangerous.
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Toxin
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Harmful proteins that damage the bodies defenses and can lead to symptoms.
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Exotoxins
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- Excreted toxins
- Very potent - Very specific affinity to certain places in the body - Thermo-labile (breaks down under high heat) |
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Endotoxins
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-Release only when cell wall disintegrates (lysis)
- No specific affinity causes systemic effects (e.g. fever malaise or shock) - Proteins are thermostable |
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Opportunistic Pathogens
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microorganisms which rarely cause disease in healthy humans but do in immuno-compromised humans
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Pathogenicity
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measurement of ability to produce disease.
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Virulence
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How much damage the pathogen can cause (degree of pathogenicity).
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Factors that determine capacity of an organism to produce disease are:
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- Transmissibility
-Routes of Entry - Pathogenicity -protect themselves - adhere to and persist on body surfaces |
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Coagulase
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accelerates plasma clotting which forms around the infection and forms a barrier from leukocytes
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Hyaluronidase
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hydrolyses polymerised hyaluronic acid (mesodermal tissue) which is the substance that holds adjacent cells together.
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Opsonization
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When an antibody modifies the surface of a capsule in a way that permits a phagocyte to take up the encapsulated organism.
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Complement
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- system of plasma proteins
- work together to resist bacteria - Some bacteria are killed by complement |
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Two types of metastatic spread
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- Baceraemia
- Septicaemia |