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The Immune System

Terms

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2 types of lymphocytes involved in immune response
T-lymphocytes and B-lymphocytes
responsible for cell-mediated response
T-cells
responsibel for humnoral antibody response
B-cells
cytotoxic T-cells
recognize and destroy cells with foreign surface antigens
plasma cells
secrete immunoglobulins thant bind to specific antigens and facilitate their removal
immunoglobulin
glycoproteins; 4 chains: 2 heavy & 2 light
Fab
fragment, antigen-binding; arms; selectively bind to antigen
Fc
fragment, crystallizable; binds to surface of cells (macrophages)
IgM
first; during primary immune response
short-lived antibody
IgM
IgG
later; during secondary immune response
long-lasting antibody
IgG
IgA
found in bodily secretions
antibody responsible for mucosal immunity
IgA
IgE
found on surfaces of mast cells and basophils
antibody responsible for allergic reactions
IgE
IgD
found on surfaces of B-cells
antibody that is little present in serum
IgD
B-cell
produces 1 kind of antibody specific for a given antigen
usually expresses IgM or IgD
B-cells
How are some plasma cells formed?
proliferation and differentiation of a B-cell
How are B memory cells formed?
when B-cells do not become plasma cells and acquire more surface antibody
What enables an organism to mount a humoral response quicly if exposed to a secondary response?
B memory cells
lack of b memory cells causes?
primary response to be slow
TH2 cells (T helper cells)
help activate B cells
How can T cells respond to antigens?
only if on surface of antigen-presenting cell APC
E.g. of APC
macrophages, dendritic cells, B-cells, and epithelial-reticular cells
MHC
major histocompatibility complex- cluster of genes on chromosome 6
MHC Class 1
all multnucleated cells of body and platelets
MHC Class 2
only on APCs
CD4 surface marker
T helper cells
t-helper cells
MHC 2 restricted
TH1 cells
promote cell-mediated immunity
TH2
promote humoral immunity
t cells that promote destruction of cancerous or virally-infected host cells and invading microorganisms
TH1
t cells that promote production of antibody against foreign antigens
TH2
CD8 surface marker
cytotoxic T cells
secrete perforins and fragmentins that cause target cell to lyse or undergo apoptosis
cytotoxic t cells
cytotoxic t cells
MHC 1 restricted
T suppressor cells
CD8 marker; suppress humoral and cell-mediated response
null cells
natural killer; spontaneous cytotoxic activity; do not require prior activation; non-specific; no MHC restriction
antibody-dependent cell-mediated cytotoxicity
NK cells
cytokines
exert inhibitory and facilitory effects on lymphocytes and APCs
e.g. of cytokines
interleukins, interferons, tumor-necrosis factor
lymph nodes
where lymph filters and returns to the blood stream
remain in lymph tissue
B-cells
recirculate b/w bloodstream and lymph
T-cells
Lymphocyte recirculation
lymphocytes cross postcapillary venules, leave lymph nodes thru efferent lymphatic vessels, and pass into channel (thoracic duct)
3 functions of spleen
1. produces humoral antibody to blood-borne antigen 2. disposes of defective blood cells and other particulate matter in the blood 3. stores blood cells and platelets
splenic pulp
parenchyma; supported on stroma; div. into red and white
2 components of red pulp
1. sinusoids-thin-walled venous cannels 2. reticular fiber networkprod. by ret. fibers w/ blood cells
pulp arteries
where arterial blood enters the red pulp
penillar arteries
smaller branches of pulp arteries; b/w sinusoids
what filters blood?
spleen
follicular arteries
branches of sheathed arteries
lymphatic sheath
composed of T-lymphocytes
lymphatic nodules
composed of B-lymphocytes
marginal zone
interface b/w white and red
complement fixation
plasma proteins combine with antigen-antibody complexes
Results of complement fixation
1. cell lysis-invading bacteia 2. chemotactic factors-attract phagoctic cells 3. phagocytosis (opsonization)
central lymphoid tissue
where new lymphocytes are produced
bone marrow
b-lymphocyte differentiation
thymus
t-lymphocyte differentiation
peripheral lymphoid tissue
aggregation of lymphocytes; sites where lymphocytes respond to antigen;
components of cental lymphois tissue
bone marrow and thymus
components of peripheral lymphoid tissue
lymphatic nodules, lymph nodes, and spleen
phagocytotic cells that possess Fc and C3 receptors
neutrophils, eosinophils, and monocytes

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