Defense Systems Flashcards
Pathogens
bacteria, viruses, fungi, protozoa, worms
nonpathogenic foreign substances
pollen, chemicals, transplanted tissue
Innate defenses
not keyed to individual pathogens, do not adapt to specific pathogens, no clonal selection
Adaptive defenses
keyed to individual pathogens, adapt to specific pathogens, clonal selection
pH of skin
low
opsonization
interaction w/ label attached to target by host’s system
opsonins
antibodies
complement proteins
acute phase proteins
cytokines
signalling molecules
Natural killer cells
attack cancerous cells/viral cells
NK recognition
unusual molecules on surface of target cell
NK killing method
release of granules containing proteins that destory target cell membrane, proteolytic enzymes that chew up target’s proteins, molecles that induce apoptosis
Early-acting defenses
NK and phagocytes
Interferons
cytokines, proteins secreted by immune system cells that regulate activities of nearby cells
Complement
30 blood serum proteins that can destory membrane of foreign cell/opsonize invader
Pyrogens
signalling molecules that tell hypothalamus to raise set point
Immunoglobulin class
set of similar antibodies
2 regions of antibody molecule
variable region-different in each antibody
constant region-same in each Ig class
epitope
part of antigenic molecule that binds antibody.
12-20a.a
what is antigenic?
proteins
glycoproteins
polysaccharides
glycolipids
T Cell Receptors
specificity, diversity, bind to antigens, diversity generated by gene rearrangements
B cell maturation site
bone marrow
T cell maturation site
thymus
B cell activation
antigen binding or interaction with helper T cell
Clonal selection
2 B cell clones from the activation of a single B cell with single antigenic specificity
plasma cells
secrete antibodies of the same specificity as B cell receptor
memory cells
no immediate role, potentiate later responses
what antibodies do
membrane-bound receptors in B cells
coat viruses and bacteria, preventing attachment to epithelia
coat cells, viruses and particles for macrophage attack
activate complement
humoural immunity
helper T cells
provide links between macrophages, dendritic cells, humoural immunity and cell-mediate immunity
APC antigen-presenting cells
macrophages and dendritic cells
Major histocompatibility complex (MHC)
presents antigen to helper t cells
cytotoxic T cells
activated by helper T cells and infected cells (killer T cells)
lyses the membrane of target cell
cell-mediated immunity
somatic hypermutation
occurs during proliferation of memory cells.
acquired immunited
vaccination
passive immunity
antibodies supplied directly from outside
eg mother to child
