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Skin and mucous membranes are the physical barriers
Physical barriers often in association with chemical barriers
steps of engulfing and killing
Endocytosis with microbe being contained in phagosome
Lysosome fuses with phagosome
Degradative enzymes along with reactive oxygen products kill microorganism
Release of debris
A set of blood proteins that when "triggered/activated"
undergo a series of chemical reactions that lead to the
killing of microorganisms, stimulate inflammation (mast cells, neutrophils), opsonization (stimulates and helps phagocytes)
membrane attack complex, composed of many C9, C5-C8 molecules, leads to holds in the membrane of the microbe
chemicals produced in response to viral infection,
act to: stimulate phagocytic T andB cells
slow viral replication in infected host cells
inhibit cancer cells
large complex molecules, organic, usually proteins, foreign particles, found on surface of pathogen, lymphocytes recognize pathogens by binding to antigens, lymphocytes have receptor molecules that bind to specific antigens
IgG 2 bonding sites, (80%)more commonly found, smallest, lives longest, crosses placenta, fixes complement, binds to phagocytes, long term immunity
IgA 2-4 bonding sites, (13%), binds to epithelial cells
IgM 10 bonding sites, (6%)less commonly found, largest, dies fastest, fizes complement, binds to NA, first response
How antibody works
precipitation of free molecules (toxins)
Cytotoxic t cells recognize cells with ________ pathogens, infected host cell has _______ on surface with ___________ molecule
intracellular, antigen, class 1 MHC
What is the APCs process?
Engulf pathogen →digest pathogen→processes antigen→presents antigen on its surface
Immune avoid mechanisms
prevention of phagocytosis-due to capsule
--Klebsiella pneumoniae, Streptococcus pneumoniae
survival w/in phagocytes
--Mycobacterium tuberculosis, Trypanosoma cruzi (chagas disease)
--Borrelia hermsii (relapsing fever), Trypanosoma bruceii (sleeping sickness)
Killed and inactivated vaccines
pathogen subjected to chemical/radiation treatment
antigens intact but pathogen destroyed
advantages-safe, no symptoms
disadvantages-requires larger dose/ frequent application
ex) pertussis, typhoid, cholera
pathogen made virulent by modifying growth conditions in lab
antigen intact pathogen capable of replicating
advantages-produce strong immune response
--less adverse reactions
disadvantages-possible mild symptoms, might become virulent again, transmissible
ex) polio(oral), measles, mumps, rubella
Subunit vaccines (acellular)
contain only antigenic portion of microbe
bacterial capsules, cell walls
advantages- few adverse reactions
--good to excellent immune response
disadvantages-newer vaccines expensive
ex) pneumococcus, HIB, hepatitis A
chemically denatures pathogen toxin
non-toxic and stimulates IR
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