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Tortora Microbiology Chap 16 Host Defenses


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Physical, chemical, and genetic barriers that block invsasion at the portal of entry
1st line of defense
nonspecific cells and fluids within the body that act after pathogens gain entry
2nd line of defense
specific activities of the immune system
3rd line of defense
These are directed against a a variety of pathogens
nonspecific host defenses
Natural host resistance when organisms pathogenic for one species may not be pathogenic for another
Species specificity
Three things that affect defenses
Age, Stress, and Diet
Skin, Mouth and nose, Stomach and intestines are examples of
Anatomical Defenses
This intact tissue serves as a barrier to penetration by microorganisms (physical barrier)
Most organisms must first establish themselves at site of infection, if the site is not compatible it will not multiply
Tissue Specificity
A reaction to an infection and mechanical injury
Inflammatory response
An abnormal increase in body temperature caused by pyrogenic organism
when the pyrogenic organism comes from outside the body
Exogenouse pyrogens
When the body itself produces a fever-inducing substance as a reaction to inflammation
endogenous pyrogens
Tissue bound phagocytes
these migrate out of blood into tissue to become macrophage
These have the ability to leave the blood, enter an infected tissue, and destroy microbes
Phagocytes kill microbes by releasing toxic forms of?
These organisms are highly resistant to phagocytosis
Encapsulated organisms
this is a localized accumulation of dead white blood cells
Pathogens that produce lukocidins
destroy phagocytes and are released alive
These pathogens are readily phagocytized but do not kill the phagocytic cell and are not killed by it
Intracellular pathogens
these can remain alive for long period of time and can even reproduce within the phagocyte
intracellular pathogens
When growing intracellularly the organism is protected from immune mechanisms of the host and is less susceptible to
drug therapy
Viruses, Chlarydias, Rickettsias, and some protozoa are examples of
Intracellular pathogens
This is a defensive system consisting of ove 30 proteins produced by the liver and found circulating in blood serum and within tissues throughout the body
Complement system
They destroy microorganisms by punching holes in their membranes "cytolysis"
Complement system
Three protein complement activations
Cytolysis (punching holes in their membranes), Opsonization (enhancing phagocytosis), and inhancing inflammatory response
Protiens produced by lymphocytes and virus infected cells that interfer with viruses
block viral multiplication in neighboring cells

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