Term
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Definition
Physical barriers
Fixed or ‘hard-wired’ mechanisms (innate)
Adaptive immune response
“” vaccination
long-term protection |
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Term
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Definition
Outer epithelial
Physical barrier
Colonization by nonpathogenic resident microorganisms
Competition for the bad pathogens to move in
What if a pathogen does move in?
Innate immune response quickly takes action to eliminate the bug
Therefore consider this: |
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Term
| Are the defenses of the innate immune response easy to assess? |
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Definition
Aren’t most infections eliminated prior to development of symptoms?
Maybe you don’t even have to see a doctor
Conclusion = innate immunity is very effective
After all we do have vast populations of resident microbes and most the time we are well
Innate response very effective and important!
Rare inheritable innate immune mechanism defects
= substantial protection reduction! |
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Term
| pathogens of diverse types |
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Definition
4 Human pathogen types
Viruses, bacteria and fungi
Parasites
Unicellular protozoa
Multi-cellular worms
Pathogens are diverse in their
Structure
Manner of exploiting the human body
Type of damage to tissue
Tissue damage and disease symptoms can be caused
Directly
Indirectly |
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Term
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Definition
Release exotoxins
Phagocytes degrade microbe, endotoxins released cytokines
Infected cells killed /damaged |
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Term
| Extracellular vs. intracellular infections |
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Definition
Different sites affect the type of immune mechanism used to eliminate the pathogen
Extracellular are accessible to soluble immune system molecules
Intracellular forms are not accessible to soluble immune system molecules
Intracellular pathogens in nucleus or cytosol attacked by killing the infected host cell
Interferes with the pathogen’s life cycle
Exposes the released pathogens from the killed cells to soluble immune system molecules
Intracellular pathogens in vesicles
Activate the infected cell to intensify its antimicrobial activity
Almost all viruses, bacteria, fungi or parasites are at some time in the extracellular system Abs |
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Term
| Most pathogens infect only a few related host species |
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Definition
Therefore humans are infrequently infected via another vertebrate species
Most of time infection is via directly or indirectly by another person
Parasites may require an intermediate passage through distantly related organism
WHY?
To complete it’s life cycle
Pathogen’s ability to persist outside of the body varies
Determines the ease with which a particular disease is spread
Anthrax = spores = resistant to heat/desiccation
HIV sensitive to environment change therefore requires intimate contact or exchange of infected body fluids |
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Term
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Definition
C3 is by far the most important molecule in the complement cascade.
The biggest difference in the different pathways is how they are activated.
1) The quickest of the 3 complement pathways is the alternative pathway
It starts depositing C3b on the surface of the pathogen at the beginning of infection.
2) The lectin pathway can begin as soon as an infection is realized but takes a little time to become effective.
3) The Classical pathway is part of both the innate and adaptive immune response and can be activated by C-reactive protein (innate) or antibody (adaptive) binding to the pathogen. |
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Term
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Definition
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Term
| Three Complement Pathways |
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Definition
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Term
| 1st Step in the alternative pathway |
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Definition
1st Step in the alternative pathway involves spontaneous hydrolysis and activation of complement component C3
This process occurs continuously at low rate in blood, lymph and extracellular fluids
Rate increases in vicinity of certain pathogens
iC3 is the product of C3 hydrolysis
iC3 binds to factor B in the blood or ECF making factor B susceptible to cleavage by factor D
at pathogen’s surface
iC3Bb is produced (soluble form of C3 convertase)
iC3Bb cleaves C3 into C3a and C3b
Some of C3b becomes bound to pathogen’s surface |
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Term
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Definition
by the alternative pathway tags microorganisms for destruction]
1st immune system components to be activated = complement
Ubiquitous in blood and lymph
Soluble proteases that circulate in an inactive form called zymogens
A molecular defense that can be utilized immediately |
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