CH33 Flashcards
describe non specific and specific resistance
nonspecific (innate defenses)
- doesn’t involve recognition of a specific parasite/pathogen
- no memory
- ex: fever
specific resistance (immunity)
- involves recognition of a specific parasite
- memory
- ex: vaccine
adaptive defenses
immunity
external and internal physical/chemical barriers
external
- skin
- mucous membrane
- chemicals secreted (lysozyme, HCl, bile)
- cilia
- sneezing
internal
- physiological responses
- cellular mediators
- soluble factors
example of physiological responses
inflammation and fever
- chemicals released by damaged tissue
- increased blood flow (vasodilation)
- increased permeability (phagocytic cells to area)
- confinement- blood clots
- pus
- tissue repair
inflammation
what causes a fever?
- body temp raises above 37 degrees C in response to pyrogens
- increased metabolic rates and heat production induced by pyrogens
phagocytic cell are
pyrogens
how is a fever beneficial to the host?
- increased phagocytic activity
- inflammation and immune response stimulated
- slows growth,especially stenothermal MOs
- iron immobilization (starving mo from iron)
- most significant
cells that contribute to innate responses
- neutrophil
- macrophage
- dendritic cell
monocytes produce
-macrophages and dendritic cells
natural killer cells are ______ and their role is to ____
- lymphocytes (non specific)
- kill tumor cells and viruses
how does a NK cell kill other cells
if cell is missing MHC class 1 molecule then the NK cells will produce perforin (makes holes) and granzymes (trigger suicide response
first line of defense for cancer
NK cells
- highly phagocytic
- originate in bone marrow, move to infected area
- short life span (3 days)
- important defense
neutrophils
- phagocytic
- develop from monocytes (blood)
- take longer to get to infection site
- can survive for months
- present antigens to lymphocytes (specific resistance)
macrophages and dendritic cells
describe phagosytosis
- phagocyte must have recognition that bacteria is there, sends chemical signal
- phagocyte attaches to bacteria
- if attachment occurs then mo is taken into cell, phagosome fuses to lysosome which will help digest/kill mo
- digestion occurs in phagolysosome
- phagocyte will get rid of left over mo (debris) and keep the nutrients
- surface markers will have antigen that forms the antigen presenting cell that will help with future immune responses to that same mo
- small proteins
- some produced in response to viral infection
- interfere with virus replication in neighboring cells
- not virus specific
interferons
interferons are innate responses bc
no memory and not virus specific
describe how interferons work
- virus infects cell and signal is sent to cell nucleus, viral replication activates host cell gene of interferon
- interferon is synthesized and released into neighboring tissue, that cell is destroyed
- interferon binds to surface of neighboring cell, signal is sent to that cells nucleus
- cell is stimulated to produce antiviral protein
- antiviral proteins block viral replication
~30 large interacting proteins (cascade produced by liver, circulate inactive form)
- stimulate inflammatory response
- enhances phagocytosis (binds to mo, aids in adhesion)
- lyse mo’s and enveloped viruses
complement defense
how do complement defenses lyse mo’s and enveloped viruses
- form membrane attack complexes (MAC)
- can destroy G- or enveloped cells
- form pore in membrane, lysozyme can get thru
aid in adhesion
opsonization
phagocytic cell with antibody and Fc receptor
- degree of binding
- opsonin
- +
- antibody
phagocytic cell with C3b and Cb3 receptor
- degree of binding
- opsonin
- ++
- complement C3b
phagocytic cell with antibody, Fc receptor and C3b and Cb3 receptor
- degree of binding
- opsonin
- ++++ (really good attachment)
- antibody and complement C3b
