Flashcards in Body Defenses Deck (36)
What are the characteristics of first line of defense?
skin, mucous membranes, normal flora
What are the characteristics of second line of defense?
phagocytes and natural killers, inflammation, complement system and interferons
What is the third line of defense?
(T and B lymphocytes)
What the mechanical factors for first line of defense?
skin - keratin
mucous membrane - cilia
what are the chemical factors for first line of defense?
skin - pH and perspiration
mucous membrane - stomach lining (gastric juices)
what are the organisms that survive the gastric juices?
polio, hep.A, protozoal cysts, H.Pylori
what is the second line of defense?
non - specific and local
what is the function of macrophages?
they phagocytize the MO by: chemotaxis and opsonization
what is chemotaxis?
attraction to the chemistry of bacteria
what is opsonization
target can be tagged with antibodies or complement proteins
what are natural killer (NK) cells
they always look for foreign cells through MHC proteins
what happens if there are no MHC proteins
then they release cocktail of perforins and granenzymes
what is inflammation
normal and non specific response to an injury
vasodilation, vessel permeability, plasma infiltration
what is complement system
a series of proteins that react non-specifically to microbes
what can complement proteins cause?
cytolysis, inflammation and opsonization
what are three important aspects of immunity
specific, systemic, and memory
what is an antigen?
any foreign substance that elicits an immune response
must be large enough to be phagocytized by a macrophage
role of macrophages in immunity
present fragments of anitgens on their own cell membranes where they are recognized by lymphocytes
what is an epitope
the specific part of the antigen that we react to
it must be present to attack
all the viruses must have it
its very tiny
size of antigen
the antigen must be large enough to generate an immune system response
too small = hapten (like a prion)
what is the sequence of immunity
1. anitgen penetrates the body and enters blood or lymphatic system
2. macrophages phagocytize the antigen
3. epitope is displayed on surface of macrophage
4. initiation of AMI or CMI
what are two types of immune responses
cell mediated (CMI) and antibody mediated (AMI)
What is CMI
cell mediated immunity ( involves T cells)
Antigen-presenting macrophage stimulates production of several diff. types of T-cells
- Helper T cells produced which stimulate the activate of B cells and cytotoxin T cells
- cytotoxin T cells (killer)- destroy the infected cells using perforin and cytotoxins
-memory T cells-distribute throughout the body, multiply rapidly on next infection
-suppressor cells - shut everything down;inhibit plasma cells and cytotoxin T cells
what is AMI
- involves B cells
- B cells become plasma cells ( which make 2000/sec antibodies and they last for 4-5days)
- memory cells - lasts for years - responsible for secondary antibody response to same antigen
what are antibodies
proteins used by lymphocytes to bind to specific antigens
how to antibodies hurt microbes
what is primary A/B response
IgM increases and peaks down to non-existent
IgG goes up at slower rate and peaks higher than IgM and suststains for longer period of time
What is secondary A/B response
IgG goes up by much faster rate because of the previous memory cells
stronger response and stays long term
the graph doesnt go back to baseline
the response is stronger, faster and stays for longer period of time
Overview of sequencess
Microbe in body -->macrophage phagocyte-->macrophages display antigen (epitope) --> can lead to B cell stimulation or T cell stimulation
if lead to B cell - plasma cells produced first and then memory
if lead to T cell --> helper T cells-->killer T cells -->memory-> surpressor