Lecture 11 Flashcards Preview

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Flashcards in Lecture 11 Deck (77):
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Adaptive immune response

specific defensive response to invasion by a foreign object, will remember a pathogen and can better fight it off. can be artificial or natural

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Natural adaptive immunity

organism or toxin enter the body and promotes an immune response

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Artificial adaptive immunity

results from an immunization with a vaccine

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Both types of adaptive immunity are ..

specific and have a memory component

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How adaptive immune response is specific

protects against one disease, don't protect against others, only exception is when 2 diseases are closely related

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How adaptive immune response has a memory component

results in a much stronger response upon re-exposure. long term immunity

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Adaptive immunity involves two general responses (branches)

-antibody mediated response (humoral response)
-cell mediated response

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Antibody mediated response

mediated by small molecules called antibodies or immunoglobulins. antibodies specifically bind to and inactivate foreign particles

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Cell mediated response

cleans up the root of the problem, triggers the activation of lymphocytes, attack bigger targets (tumors)

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Lymphocytes

recognize and destroy abnormal and infected host cells

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Antigen

foreign particle that enters the body, what your responding to

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Body responds to an antigen by

-producing antibodies (Ab) to the antigen
-triggering specific killer cells

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Producing antibodies to the antigen are also referred to as the

humoral response

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Triggering specific killer cells

destroy large antigen and abnormal infected host cells. cell mediated immune response

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Epitopes

antigen broken down into smaller parts, particular portion of the antigen thats recognized by the antibody

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Antibodies

proteins produced in response to the antigen. bind to the antigen in a specific manner (lock and key)

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Antibodies (Ab) =

immunoglobulins (Ig)

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Antibodies are made of 4 parts.. and held together by..

-2 identical heavy chains
-2 identical light chains
-by covalent bonds

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Each antibody has..

-2 identical antigen binding sites (Fab)
-a constant fragment (Fc)

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Fab is specific for..

one epitope

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Fc binds ..

complement proteins and phagocytes

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5 classes of antibodies

-immunoglobulin G
-immunoglobulin M
-immunoglobulin A
-immunoglobulin D
-immunoglobulin E

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Immunoglobulin G

most common, found in the blood, can also enter tissues in regions of inflammation, cos placenta and confer passive immunity to fetus, binds to antigens tightly

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Immunoglobulin M

pentamer, it remains in blood, often found attached to surface of B cells, very good at aggregating antigens, can bind up to 10 antigen

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What is the first type of antibody produced upon infection

Immunoglobulin M

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Immunglobulin A

found as a dimer (two antibodies stuck together) and in bodily secretions. functions to protect mucosal surfaces, protects GI tract of new borns. can bind to 4 antigens

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Immunoglobulin D

unknown function

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Immunoglobulin E

found on surface of certain immune cells, mast cells and basophils, when it binds to antigen cell releases histamine, attracts complement and phagocytes to area

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Histamine

responsible for allergy symptoms

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6 steps of the function of an antibody

-agglutination
-neutralization
-complement activation
-opsonization
-antibody dependent cytotoxicity
-immobilization and presentation of adherence

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Agglutination

antigens become stuck together, this reduces the number of infectious units to be dealt with

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Neutralization

Ab binds to and inactivates toxins bacteria and viruses, 1st step in eliminating virus in the body

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Complement activation

antibody binds to bacteria, this acts as starting point for the complement pathway (MAC attack)

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Opsonization

flags down phagocytic cells to destroy the antigen

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Antibody dependent cytotoxicity

antibody flags down cells of the immune system to destroy abnormal/infected body cells

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Immobilization and prevention adherence

antibody binds flagella to inhibit movement of pathogen, and binds to pili to stop adherence of pathogen

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Cells of adaptive immune system

-lymphocytes
-antigen presenting cells

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2 types of lymphocytes

-B lymphocytes
-T lymphocytes

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B lymphocytes (B cells)

antibody producing cells, involved in the humoral or antibody mediated response, produced in bone marrow by stem cells

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T lymphocytes (T cells)

produced in the bone marrow but mature in the thymus gland

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2 types of T cells

-helper T cells
-cytotoxic T cells

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Helper T cells

help B and Tc cells prepare for an immune response, part of humoral and cell mediated immunity

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Cytotoxic T cells (Tc)

cells lyse foreign and abnormal host cells, part of cell mediated immune response

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Antigen presenting cells (APC)

macrophages, B cells, dendritic cells. looks for antigen that shouldn't be in tissue

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Endogenous antigen

originates inside of a comprised cell

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Exogenous antigen

antigen presenting cells CHOOSE to take up exogenous antigen

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T helper cells =

CD4 (MHC2 goes with CD4)

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Cytotoxic T cells =

CD8 (MHC1 goes with CD8)

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Stages of antigen presenting cell

-foreign material such as bacterial cell is engulfed by the APC
-antigen is processed and presented to the T help cells of immune system along w/ self antigens (check to prevent destruction of own cells)
- T helper cells become activated against the foreign material

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Self antigens

theses are part of the major histocompatibility complex (MHC)

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Stages in antibody production

-antigen enter the body (small fragments of the antigen will be present on the surface of B cell with the MHC)
-a T helper cell will bind to the antigen presenting B cell after recognizing the antigen bound to the MHC protein
-the T helper cell will then deliver cytokines that stimulate the B cell to undergo expansion

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During antibody production the antigen enter the body and will be...

phagocytized and digested by a B cell

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Clonal expansion

B cells divide and differentiate becoming either plasma cells or memory cells

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Plasma cells

antibody producing cells, have short lifespan and produce many antibodies

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Memory cells

live for long time (20 yrs), circulate in blood and propagate at low level

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When memory cell encounters an antigen it will..

quickly change, multiplying and booming an antibody producing plasma cell

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Primary response

response the 1st time the body encounter the antigen. the antigen stimulates the production of low levels of antibody, slow process (5-7 days)

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In primary response which antibody is produced first

IgM, then followed by IgG (blood) and IgA (mucous membranes)

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Major outcome of primary response

memory is built for the antigen

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Secondary response

response that occurs during every subsequent encounter with the antigen, high levels of antibody produced, quick response (1-2 days) which results in quick overcome, memory cells are replenished

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Cell mediated immune response

is activated by invading cells/abnormal host cells. involved APC, T helper, and cytotoxic T cells

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Cytotoxic T cells are responsible for..

destroying abnormal cells in the body

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Stages of cell mediated immune response include

-recognition of abnormal host cells
-T cell activation
-endogenous antigen is processed and displayed on cell surface
-perforins and granzymes

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Recognition of abnormal host cells could be..

-virus infected cells
-bacteria infected cells
-cancer cells
-foreign cells

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T cell activation

dendritic cell engulfs foreign antigen, present antigen to a specific Tc (activated to undergo clonal expansion)

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T cell activation produces..

-memory T cells
-cytotoxic T lymphocytes (CTLs)

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Endogenous antigen is processed and displayed on cell surface

presented on the surface if the APC together w. the MHC1 self antigen, diff type of MHC then used during the Ab mediated response

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Perforins

released from the cytotoxic T cells, poke holes in the membrane of abnormal cell

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Granzymes

released from cytotoxic T cells, cause the infected cell to undergo apoptosis (programmed cell death)

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Active immunization

body goes through the complete process to generate specific antibody or cytotoxic T cells

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Active immunization can be ..

natural or artificial

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Natural active immunization

when the antigen is encountered from the environment (primary response)

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Artificial active immunization

when the antigen is injected as vaccine

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Passive immunization

given ready made antibody, does not result in lasting immunity

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Passive immunization can be either ..

natural or artificial

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Natural passive immunization

ex: from mother to infant, IgG is transferred from mother to fetus via placenta, IgA is transferred from mother to child via milk

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Artificial passive immunization

pre-made antibody is injected, very fast acting for life threatening situation (ex: snake venom)