Pathogen and Host Flashcards by Tara Adhikari

What is a pathogen?

A disease causing organism.

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What is a commensal?

An organism that is part of the normal flora.

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What is pathogenicity and what is does it depend on?

The capacity of the microorganism to cause infection.
This depends on:
Infectivity (ability to become established)
Virulence (ability to cause damage)

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Give some examples of Infectivity.

attachement, and acid resistance.

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Give some examples of Virulence.

invasiveness
necrotising fasciitis
cellulitis
connective tissue breakdown

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What is an exotoxin?

a toxin released extracellularly by microorganism.

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What is a enterotoxin?

Toxin that acts on GI tract.

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What is an endotoxin?

found on gram negative cell - lipopolysaccharide coat.

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Give some features of viral pathogenesis.

Cell destruction, changes to gene expression, immunopathogenic disease/

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Give an example of cell destruction caused by viral pathogenesis.

HIV killing T4 cells

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Example of changes to gene expression by viral pathogenesis

Tumour viruses - Human papilloma virus

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example of immunopathogenic disease causing virus.

Influenza A.

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What is innate immunity?

Immunity you are born with.

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Are phagocytotic cells part of acquired or innate immunity?

Innate Immunity.

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What are polymorphs?

Phagocytic cells - white blood cells.

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Name three polymorphs.

Neutrophil, eosinophils, basophils.

what is a neutrophil?

First line of defence.

What is a easonophil?

Takes larger pathogens. allergic response.

What is a basophil?

Makes histamine and heparin - triggers inflammation.

Give some examples of phagocytotic systems

Spleen cleaning blood
Liver cleaning entero-hepatic circulation
Lymph nodes cleaning peripheral sites.

What is opsonisation?

Pathogen coated with antibody/ complement - killed better as it attracts more killer cells;.

What is acquired immunity?

You aquire it.
Immunological memory.
Specific response to antigen.

What is humoral immunity.

Macromolecules in extracellular fluid. Usually protect against bacterial infection.

What is cell mediated immunity?

antigens presented by macrophages, stimulates T cells. used for viral infection.

Give an example of a exotoxin.

tetanus.

Give an example on an enterotoxin.

Cholera

Name a few sights of viral entry.

Conjunctiva. Skin. Respiratory tract etc.

Give an example of a acute virus infection.

Influenza A.

What is an enterovirus.

Affects the control of the GI tract.

What is viraemia?

Presence of the virus in blood.

Are acute virus infections localised ?

Yes - but if there is a widespread infection of tissue then there may be the development of viraemia.

What is Antigenic Drift?

Minor changes in the genes of flu viruses, occurs over time to have slightly different viruses.

What is Antigenic Shift?

Abrupt major changes in virus structure.

Enteroviruses usually pass through the GI tract and are excreted in faeces. What could happen if they don't?

They could go into the blood (viraemia) And go to non-neural tissues or neural tissues. IF they go to neural tissues, this can lead to paralysis.

Give an example on a latent virus infection.

Herpes simplex virus.

For the herpes simplex virus, where is it when its active and where is it when its dormant?

``` Active = epithelium Latent = Nucleus ```

When the virus is latent, can it replicate?

Nope.