immune system (innate) Flashcards
when is innate defence present?
at birth. always at work.
it is non-specific
what does innate defence include?
physical barriers
cellular defense
chemical defense
inflammation
what is the first line of defense?
physical barriers
what are the 2nd line of defense?
cellular and chemical defense
what is a physical barrier?
skin and mucous membranes
epithelial membranes- form physical barriers and produce secretions
antimicrobial secretions include?
acid, enzymes, mucous, defensins, dermcidin
acid..?
skin vaginal and stomach secretions have low pH inhibits bacterial growth
enzymes?
lysozyme in tears and saliva LYSES bacteria. proteases digest microorganisms
mucus?
sticky secretion in respiratory/ digestive passages; trapsmicroorganisms
defensins?
antimicrobrial peptides secreted by mucous membranes; inhibit bacterial and fungal growth
dermcidin?
secretion in sweat that is toxic to bacteria
what is cellular defense?
phagocytes. example= macrophages derived from monocytes; may be free or fixed. also neutrophils.
cellular defense: intracellular killing
engulfs bacteria by phagocytosis, lysosomal enzymes digest the pathogen! food. yum.
what are TLRs
toll like receptors! phagocytes have these special buddies that recognize the pathogen associated molecules! cool little detectives.
cellular defense: extracellular killing
neutrophils degranulate, so they release granules that contain toxins.
can be: proteases, defensins, free radicals
proteases- protein digesting enzymes
defensins- pierce holes in cells
free radicals- oxidizing chemicals
what is NET….
last resort…. suicide of the neutrophils! they release their genetic material and net bacteria, and they DIE… :(
stands for neutrophil extracellular trap
what are natural killer cells….. NK cells..
IMMUNE surveillance….. special granular lymphocytes that recognize and attack abnormal cells
they release cytolytic chemicals… these chemicals destroy cells that are virus infected or cancerous
steps of the NK cells on attack..
- recognize abnormal cell
- AIM. align golgi apparatus
- FIRE. perforin makes holes and granzymes enter cell
- APOPTOSIS- programmed cell death
normal flora and cellular defense?
inhabit epithelial surface, increase competition and stimulate defense mechanisms to protect against pathogens
chemical defense?
chemicals circulating in blood or released by injured/infected cells and leukocytes
pyrogen
released by phagocytes exposed to pathogens
FEVER…. alters temp set point in hypothalamus. increased temp accelerates repair and enhances activity of immune cells
interferons
secreted by virus infected cells
“interfere” with replication in nearby cells and attract NK cells
complement
group of plasma proteins, activated by microbes, activation cascade.
made in the liver, circulate in blood.
3 main pathways of complement
classical
alternative
lectin
classical pathway?
contacts an antigen-antibody complex
alternative pathway?
contacts surface of a microbe
lectin pathway?
contacts plasma protein lectin bound to sugar mannose on surface of pathogen
how does complement activation enhance phagocytosis?
makes the pathogens very yummy!!
how does complement activation enhance inflammation
causing mast cells to release histamine!!
how does complement activation enhance chemotaxiss
creates chemical trail that attracts leukocytes!!
how does complement activation enhance cell lysis
forms a membrane attack complex which creates holes in cell membranes!!
what is the formation of the MAC complex
cascade of activation events results in an assembly of complement proteins that insert into the bacterial cell wall, form pores and holes and cause LYSIS of cell as water rushes in
inflammation is..?
non-specific response triggered by tissue injury, chemical irritation, pathogens
4 cardinal signs
swelling
redness
heat
pain
during inflammation basophils and mast cells…
release inflammatory mediators (histamine, kinins, prostaglandins; complement proteins activated)
3 main effects from the infection/injury
vasodilation, increased capillary permeability and attracts wbcs (chemotaxis)
vasodilation causes
hyperemia (increased blood flow)
causes redness and heat
causes more nutrient supply, more repair
increased capillary permeability causes
fluid leakage and leukocytes escape from blood into c.t
“diapedesis”
swelling and pain
chemotaxis causes
fight pathogens, dispose of damaged cells
what is margination
leukocytes stick and roll along blood vessel wall
