Immunity Flashcards
Innate System
born with it, non specific, form first and second line of defense
adaptive system
specific, third line of defense, must be primed
first line of defense
skin and mucous membrane barrier, physical barrier, epithelial cells produce protective chemicals
Functions of first line of defense (5)
- acidity of skin secretions inhibit bacteria
- stomach mucosa secretes HCL and enzymes
- Saliva and Lacrimal fluid contain lysozyme
- Mucosa traps bacteria
- Cilia sweep mucosa away from lung
second line of defense
internal defense, nonspecifc
when is second line activated
when specifc carbohydrates on bacteria, fungus, virus are recognized
parts of the second line of defense
phagocytes, natural killer cells, inflammatory, antimicrobial, inferons, complement, cell lysis, fever
phagocytes
eat pathogens that enter the body
macrophages, white blood cell
chief phagocyte
macrophages
free macrophages
wander from tissue to tissue
fixed macrophages
kupffer cells in liver, microgilia in brain, langerhan cells
neutrophils
most numerous WBC, become phagocytic when encounter pathogen
eosinophil
weakly phagocytic
mast cells
ingest a wide range of bacteria
mechanism of phagocytosis
phagocyte recognizes CHO, adheres pathogen, engulfs pathogen via pseudopods, fuses with lysosome forming phagolysosome, killed by enzymes
Pneumococcus
complex CHO that phagocytes cannot bind to, bacteria must be opsonized, then phagocyte can bind
tuberculosis bacillus
resistant to lysoxomal enzymes, need help of adaptive cells
natural killer cells
cytotoxic lymphocytes, police blood and lymph
mechanism of natural killer cells
recognize stressed cells, release perforins that put holes in cell membrane, release chemicals that enhance inflammatory response
inflammatory response
trigged when body tissue is damaged
what does the inflammatory response do?
prevents spread of damage, allows repair, disposes of debris and pathogens
steps of inflammatory response
- chemical alarm
- leukocytosis
3.margination - diapedisis
- chemotaxis
leukocytosis
chemicals allow release of neutrophis from RBM
margination
endothelial cells sprout adhesion molecules, neurophils have integrins that bring together and cling to capillary wall
diapedisis
neutrophils squeeze out of capillary
chemotoaxis
chemicals attract neutrophils and WBC to site of injury
what are the chemicals that flood into the cells from?
injured tissue cells, phagocytes, lymphocytes, mast cells
type of chemicals flooding
histamine, kinins, PG, complement, cytokines
phagocyte influx
first mast cells, neutrophils, macrophages
antimicrobial proteins
enhance innate defenses, attack pathons directly or stop growth
interferons
what infected cells use to signal uninfected cells to fight stimulate PKR, activate macrophages and mobilize NK cells
PKR
interferes with viral replication
steps of interferons
- virus enters cell and replicates
- Interferon gets turned on
- Cell produces interferon molecules
- interferon binding stimulates cell to get turned on genes for antiviral proteins
- antiviral proteins block viral reproduction
complement system
set of 20 plasma proteins normally inactive
get activated by classical and alternative
classical
antibodies bind to pathogen then C1 binds to Ab/Ag complex and cascade is activated
alternate
trigged when 3 proteins (B, D, P) bind to antigen then cascade is activated
cell lysis steps
C3b binds to pathogen then MAC is inserted then MAC opens hole in membrane then lysis
MAC
membrane attack complex that creates pores that lyse cell
C3b
proteins of opsoniation which allow macrophages and neutrophils to adhere and label for destruction
C3a
stimulate mast cells and basophils to release histamine
fever
increase cellular metabolism and speeds up repair
viruses
nucleic acids surrounded by a protein coat, invade host cells and use the cells machinery to produce viral copies
adaptive system
must be primed, is systemic, has memory
2 sections of adaptive system
humoral and cell-mediated
cells of adapative system
b cells, t cells, APCs
B cells
humoral immunity
t cells
mature in the thymus, cell mediated
APCs
engulf pathogens and present a fragment of the cell to be easily identified by T cells
humoral immunity
antibody mediated immunity
humoral immunity mechanism
antigen binds to b-cell receptors and stimulates B cells to rapidly divide into plasma cells and memory b cells
plasma cells
main producer of anitbodies, ciriculate through humors to bind to antigens and tag them for destruction
memory b cells
primed to respond to same antigen, secondary response
cell mediated immunity
completes immunity, activated by t cells: CD4 and CD8
CD4 cells
t helper cells, primed by apc, stimulate other t cells and b cells to divide
CD8 cells
cytotoxic t cells, killer t cells, circulate through humors, main target are virus infected cells
class 1 MHC
CD8
Class 2 MHC
CD4
mechanism of t cells
t cells bind to target cells and release perforin, cell detaches, target cell lyses
other t cells
t supressor, TDH, delta and gamma t cells
t supressor cells
secrete cytokines that suppress t and b cells, decrease and stop immune response
TDH
promote allergic reactions
delta and gamma t cells
live in intesitne
antigen
substances that evoke an immune response
lymphocytes
orginate in RBM, make t cells and b cells
selection process for t cells
positive and negative selection
positive selection
must recognize self major histocompatibility proteins, if it fails-aptosis
if success- proceeds to negative selection
negative selectin
t cells must no recognize
if recognizes- apoptosis
failure to recognize-sucess
antigen presenting cells
these cells engulf pathogens and present fragements of these anitgens on their surface
antibodies
immunoglobulins, solube, gamma globulins
MADGE
IgM
1st to be released by cells, can fix complement system, biggest antibody
IgA
a dimer, the secretory Ig found in mucous, helps prevent pathogens from entering body, prevents attachment of pathogens to epithelial membranes
IgG
most abundant, first and secondary response, crosses placemta
IgE
never found in blood, allergies
function of Abs
do not destory but they inactivate and tag for destruction
neutralization
simplest, block specific sites on viruses and bacterial toxins, cannot bind to receptors on tissue cells
aggrutination
clumping by IgM
precipitation
soluble molecules are cross linked-insoulbe precipitate, makes molecule more easily engulfed
complement fixation
abs bind to cells, change shape and expose binding sites then fization then cell lysis
HIV
targes t helper cells
new cancer treatment
treating ALL with t cells
