lect 24: immune and lympathetic system I Flashcards
what are characteristics of innate immunity
lack immune specificity and memory
response=inflammation
neutrophils are the first responders
what are the characteristics of acquired immunity
develops in response to antigens
more powerful than innate immunity
takes longer to develop
displays specificity and memory
what is passive immunity
temporary immunity due to donated antibodies
what is active immunity
long-lasting/permanent immunity due to self-exposure to antigen resulting in memory T cells and B cells specific for antigen
what are the 2 types of acquired/adaptive immunity
humoral: antibody mediated; plasma cells
cell-mediated: T cells, B cells & antigen presenting cells
define primary lymphoid organs
precursor cells mature into immunocompetent cells. Each is programmed to recognize a specific antigen (Thymus and bone marrow)
define secondary lymphoid organs
trapped antigens stimulate clonal expansions of mature T and B cells (lymph nodes, spleen, tonsils)
where do lymphocytes originate
primary lymphoid organs
where do lymphocytes take up residence
secondary lymphoid organs
what are attributes of lymph follicles (nodules)
not enclosed within a capsule
occur singly or in aggregates
are sites of B cell localization and proliferation
transient
what are attributes of primary follicles
spherical, tightly packed accumulations of virgin B cells and dendritic reticular cells that have not been exposed to antigens
what are attributes of secondary follicles
derived from primary follicles that have been exposed to non-self antigens.
Not present at birth
what are attributes of the corona (cortex) of secondary lymph follicles
darker peripheral region
composed of densely packed B lymphocytes
central, lighter stained region
composed of B lymphocytes, memory B cells, plasma cells, dendritic reticular cells which function as antigen-presenting cells
Germinal center of secondary lymph follicle
T/F: lymph capillaries are present in lymphoid follicles
FALSE: they are not present
where is subcutaneous-associated lymphoid tissue found
papillary layer of the dermis
what does the lamina propria-associated lymphoid tissue include
MALT, BALT, GALT
what does aggregated lymphoid tissue include
various tonsils and Peyer’s patches in the ilium
where do all immune system cells originate
bone marrow
where do immature T cells travel to?
thymus
where do B cells travel to
specific regions in lymphoid tissues
what cell surface receptors are needed for the maturation of B cells
IgM and IgD
MHC class II proteins
Complement receptors
Ig Fc receptors
what are the 5 classes of antibodies
IgA, IgD, IgG, IgM, IgE
what does the highly variable region of antibodies recognize
antigen and Fab fragment
what are components of the less variable regions of the antibody structure
Fc fragment and binds antibody to cells
where is IgA found
saliva, GU and respiratory tracts
where is IgD found
found on surface of B cells traveling to lymphoid organs
what is IgG
major Ig in blood
responsible for most antibody activity
what is IgE
associated with allergic responses
what is IgM
first antibody class expressed by developing B cells
what is the main function of MHC gene products
presentation of antigenic peptides to T cells
where is MHC 1 expressed
surface of all cells except trophoblast and RBC
where is MHC 2 expressed
surface of B cells and antigen-presenting cells
what do CD8+ T cells do
recognize peptide fragments of foreign peptides bound to MHC class I on the surface of cells (antigen present cell)
cytolytic T cells
undergo mitosis
mediators of cell immunity
what is required for the binding of MHC 1 protein fragments
both CD8 and T cell antigen receptor
what does CD4+ do
recognizes peptide fragments of foreign proteins bound to MHC class II proteins on surface of APCs
Helper T cells
assist CD8+ cell differentiation
assist B cell differentiation
what releases Fas ligand
CD8+ T cells
what is another name for CD16+ T cells
natural killer cells
what does interleukin-2 do
stimulates proliferation of NK cells
what does interferon gamma do
activates NK cells
what does Tumor necrosis factor do (TNF-beta)
kills tumor cells directly
what region of the class I MHC does CD8 bind to
alpha 3 region
what does coreceptor CD4 bind to
beta 2 region of class II MHC
what happens to activated T cells that undergo mitosis
either become memory cells or secrete interleukins
what do B cells that undergo mitosis become
either plasma cells (which secrete appropriate antibodies) or memory cells
what do cytokines do
activate macrophages to become more effective in killing target cells
what is the classic pathway of the complement system activated by
antibody binding to a pathogen
what is the alternate pathway of complement system activated by
directly activated by the pathogen
what does the complement system facilitate
inflammatory responses
what initiates the complement cascade
C1q binds to Fc region of Ig–> activates C1r–> activates C1s–> initiates complement cascade
what is the most important opsonin
C3b
what forms the pores in the membrane of the pathogen in the complement system
C6, C7, and C8
what activates the MAC
complement cascade
define opsonins
coatings that make the antigens more palatable to phagocytes
consists of cells that typically pack areas of the lymphoid organ (mostly lymphocytes)
parenchyma
consists mostly of reticular fibers and cells, including undifferentiated cells and fixed and free macrophages
stroma
define Hilus
entry and exit point for vessels
what enters through the hilus
efferent lymphatic vessels as well as arteries and veins
where do afferent lymphatic vessels enter in lymph nodes
convex side of the node
what fibers are in the capsule
dense collagen fibers, some elastic fibers, and smooth muscle fibers
what are attributes of the deep (inner) cortex)
contains T helper cells, macrophages
HEVs
define High endothelial venues (HEVs)
port of entry for circulating differentiated lymphocytes to seed lymph node
irregular arrangement of loos medullary sinuses and dense medullary cords
site of lymphocyte reentry into lymph stream
thymic-dependent areas in subcortical and deeper medullary regions
medulla
