BYU General Microbiology Chapter 9 – Dr. Robison – Flashcards

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3rd line of defense
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specific/acquired immunity
smart system with a memory
acquired over time
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immunologists
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scientists who study cells and chemicals involved in specific immunity
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antigens
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molecules that trigger a specific immune response
anything that is not part of the host
pieces of microbes' cells
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lymphatic system
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screens tissues of body for foreign antigens
lymph is picked up into lymphatic vessels, filtered by nodes, dumped back into blood in subclavian veins
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lymphatic vessels
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one-way system, pushed up by muscle contraction
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primary lymphoid organs
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Where lymphocyte maturation takes place
thymus
bone marrow
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thymus
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where T cells mature
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Bone marrow
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where B cells develop
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where does the B in B cells come from?
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the Bursa of Fabricius in chickens
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secondary lymphoid organs
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where immune response takes place
lymph nodes
spleen
MALT (tonsils, adenoids)
GALT (Peyer's patches)
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Lymph nodes
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house leuocytes
recognize and attack antigens
concentrated in:
neck
armpits
groin
abdomen
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cortex of lymph nodes
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B cell neighborhood
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pericortex of lymph nodes
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T cell neighborhood
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Spleen
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similar ins structure and function of lymph nodes
filters blood
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MALT and tonsils
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Physically traps foreign particles
MALT:(mucosa associated lymphoid tissue)
appendix
lymph tissue in respiratory tract
Peyer's patches in the wall of sm. intestine
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B Lymphocytes
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arise and mature in bone marrow
mostly found in secondary lymphoid tissue
small percentage in blood
after they find antigens they divide into memory B cells and plasma cells. plasma cells = antibody factories
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Antibodies
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AKA immunoglobulins (Ig)
bind antigen
secreted by plasma cells
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Antibody function
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complimentary shape to antigenic determinants (epitopes) close fit -> strong, non-covalent interactions
4 functions:
neutralization
opsonization
agglutination
activation of complement
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5 classes of antibodies
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IgG, IgA, IgM, IgE, IgD
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IgG
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main serum workhorse, only class that crosses placenta, looks like Y, longest serum half life, most common in blood, can fix complement
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IgA
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major Ig in secretions, monomer form looks like Y, (usually) dimer form looks like >-<, body makes the most of this, has a J chain
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IgM
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fix complement w/ IgG, pentamer, first antibody produced to a new antigen, has J chain
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IgE
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allergies, attaches to mast cells and basophils. Looks like a Y
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IgD
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B cell receptor, never secreted. Looks like Y
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B cell Receptor
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an antibody that stick out of the cytoplasmic membrane- it only can recognize one antigenic determinant.
each B lymphocyte has multiple copies of a single type of BCR (IgM or IgD) on its surface.
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T lymphocytes
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made in red bone marrow, matured in thymus
circulate in lymph, blood, and secondary lymphoid tissues
see small fragment of cells
bind loosely to self MHC cells,
have to bind strongly to self cells w/ foreign antigens
95% have to kill themselves bc they don't work properly (remember: T for tragic suicide)
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4 types of T lymphocytes
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Cytotoxic T cells
3 types of helper T cells:
TH1
TH2
TFH
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Cytotoxic T cells
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KISS OF DEATH
have a CD8 cell surface glycoprotein
directly kill certain cells:
cell infected with viruses/other pathogens
abnormal cells (like cancer cells)
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Helper T cells (TH cells)
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have CD4 cell-surface glycoprotein
help regulate activities of B cells and cytotoxic T cells
secrete cytokines
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cytokines
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soluble protein messengers
determine which immune response will be taken
signal between leukocytes to make cytokine network
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TH1 (type 1 helper T cell)
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cell mediated immunity
help develop cytotoxic t cells
help activate macrophages
release cytokines
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TH2 (Type 2 Helper T cell)
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mucosal barrier
help make B cells and antibodies
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TFH
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help B cells enter cycle and clone
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Different Cytokines
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Interleukins (ILs)
Interferons (IFNs)
Growth Factors
Tumor Necrosis Factors (TNFs)
Chemokines
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Interleukins
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Signal among leukocytes
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Interferons
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antiviral proteins- may act as cytokines
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Growth Factors
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proteins that stimulate stem cells to divide so there are enough leukocytes
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Tumor Necrosis Factors (TNFs)
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secreted by macrophages and T cells
kill tumor cells
regulate immune responses and inflammation
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Chemokines
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signal leukocytes to go to site of infection/inflammation
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MHC
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Major Histocompatibility Complex
important in determining the compatibility of tissues for successful grafting
2 classes of antigens:
MHC class I
MHC class II
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MHC class I antigens
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found on membranes of most nucleated cells
closed on ends
hold a peptide fragment from an intracellular protein to present to T cells (endogenous)
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MHC class II antigens
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found only on APCs
open on ends
hold a peptide fragment from an extracellular protein to present to T cells (exogenous)
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T independent antigen processing
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big, easily accessible antigens
don't need help from T cells in order to bind to B cells
stimulate B cells to differentiate
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T dependent antigen processing
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smaller, less accessible antigens
B cells need help from helper T cells to target the antigen, antigen presenting cells help T cells recognize antigen- can be exogenous or endogenous
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precessing Exogenous antigens
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antigen processing cell eats up the pathogen and breaks it down inside a little endosome.
MHCII gets added to endosome.
The pieces of the antigen attach to the MHCII molecule then the endosome fuses with the cytoplasmic membrane.
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processing Endogenous Antigens
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a proteosome inside the cell crushes antigen and sends pieces to the ER
The pieces attach to MHCI molecules.
Golgi body puts them in a vesicle
vesicle fuses with the cytoplasmic membrane
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humoral immune response
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against exogenous pathogens
B cells activated
antibody made
Memory B cells made
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plasma cells
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B cells differentiate to make mostly plasma cells
antibody factories- T helper cells say which class to make
filled with rough ER (-> makes protein antibodies)
die young
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Memory B cells
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made by differentiated B cells
don't secrete antibodies but have receptors for the antibodies
die old
live in lymph
make a faster response if antigen comes again
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Cell-mediated immune response
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respond to pathogens that are in host cells like viruses
T cells and macrophages respond
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Acquired immunity
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develops during host's life
naturally acquired v. artificially acquired
active v. passive
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