immune system p. I Flashcards
body defenses
defense systems against foreign materials like bacteria, fungi, and viruses
nonspecfic defense system
NSDS
innate defenses
mechanisms protect against variety of invaders
responds immediately
includes skin, vaginal secretions, stomach muscosa, saliva/lacrimal fluid, + digestive/respiratory pathways
specific defense system SDS
adaptive defenses
this system required for each type of invaders
this is the immune system
NSDS first line of defense: skin
acts as physical barrier to foreign matter
sebum is toxic to bacteria
pH of skin is acidic to inhibit bacterial growth
NSDS first ds: vaginal secretions
very acidic
NSDS first ds: stomach mucosa
secretes hydrochloric acid + has protein digesting enzymes
NSDS first ds: structural modifications of mucosae
- mucus coated hairs inside nasal cavity trap inhaled particles
- respiratory tract is ciliated which sweep debris and mucus to mouth to prevent lung entrance (can promote bacterial growth)
when surface barriers are breached second line of defense comes
NSDS second ds: phagocytosis
phagocytes meet pathogens that pervade mechanical barriers
these are neutrophils + macrophages, freely wandering through tissue spaces or are stationary
flowing cytoplasmic extensions of phagocytes enclose foreign material in vacuole which fuses with lysosomes and is digested
stationary phagocytic cells
Kupffer cells in liver + microglia in brain
events of phagocytosis
- microbe adheres to phagocyte
- phagocyte engulfs particle
- phagocytic vesicle (phagosome) fuses with lysosome (phagolysosome)
- microbe in phagolysosome is digested by lysosomal enzymes
- indigestable + residual material removed by exocytosis
NSDS second ds: natural killer cells
NK found in blood + lymph
unique group of granular lymphocytes
lyses cancer cells and virus infected cells
act spontaneously due to certain sugars on intruder cell surface
perforins
lytic chemicals released by NK cells bc they are not phagocytic
target cells then does apopstosis (programmed cell death, membrane + nucleus disintegrate)
NSDS second DS: inflammatory response
triggered when body tissues are injured
redness, heat, swelling, + pain are four main signs
results in chain of events for protection and healing (R HSPa)
some other say limitation of joint movement is fifth sign
inflammatory response first chain of events
- macrophages: surface membrane receptors (Toll-like receptors) release cytokines
- mast cells release histamines
- injured cells release inflammatory chemicals like histamines, kinins, prostaglandins, leucotrienes, + complement
inflammatory response first step
- first chain causes blood vessels in involved area to dilate + increases blood flow to area hyperemia causes redness and heat
IR second step
- capillaries become leaky causing plasma to leak from bloodstream into tissue spaces edema + swelling present
IR third step
edema activates pain receptors in area
IR fourth step
attracts phagocytes + wbcs to area
chemotaxis effect because cells are following chemical gradient
functions of IR
- IR prevents spread of damaging agents to nearby tissue
- disposes of cell debris + pathogens
- sets stage for repair
hour after IR
- neutrophils perform diapedesis
- neutrophils do chemotaxis
- neutrophils engulf damaged/dead tissue cells and pathogens
next in healing process
- monocytes leave bloodstream + follow neutrophils into area
- monocytes become macrophages after 12 hours become ravenous
- continue to battle, replace neutrophils
- responsible for final disposal of cell debris
other protective events in healing process
- clotting proteins are activated + close damaged area with fibrin (prevents pathogen spread)
- fibrin mesh forms network for permanent repair
- local heat increases metabolic heat of tissue cells + speed up repair processes
pus
mixure of dying/dead neutrophils, broken down tissue cells + living/dead pathogen
may form in wound after long battle, creamy + yellow
sac of walled off pus
abcess
surgical drainage is usually necessary
digestion resistant bacteria
TB is resistant to macrophages + remain within them
infectious granulomas
tumor-like growths w/ central region of infected macrophages, outer later of uninfected macrophages + outer fibrous capsule
can be asymptomatic for years but weaken immune system
NSDS sd: antimicrobial chemicals
important antimicrobial chemicals: complement proteins + inferferon
complement:
group of at least 20 plasma proteins, circulate in blood inactive
complement fixation
complements activated when encounter and attach to foreign cells
attach to pathogen membrane and form membrane attack complex which cause cell lysis
result of complement fixation
- formation of membrane attack complexes which produce lesions in foreign cell surface, causes cell lysis
- complement fixation amplifies inflammatory process
vasodilator
one type of molecule released by activation process
chemotaxis chemicals
attract neutrophils + macrophages into region
opsonization
other molecules cause cell membranes of foreign ells to become sticky
antibody binds to cell membrane of pathogen marking it for ingestion for phagocyte
NSDS sd: antimicrobial chemicals inteferons
viruses can’t make ATP or proteins on their own so enter host cell + reproduces
virus infected cells cant save themselves but can save other cells
interferons
proteins secreted by virus infected cells
bind to healthy cell surfaces to inhibit virus binding
fever
systemic response to invading microorganisms
increases metabolic rate of tissue cells + speed up process
body temperature
regulated by part of hypothalamus
set at 98.6 F or 37 C
can be reset upward by pyrogens
pyrogens
chemicals secreted by WBCSs + macrophages exposed to foreign cells/substances in body
high fevers
dangerous bc it scrambles enzymes + other body proteins
mild/moderate fever
benefits body bc liver and spleen gather up nutrients iron + zinc that bacteria needs, making them less available
specific defense: third line of response
immune system
three aspects
- antigen specfic (recognizes + acts against particular foreign substances)
- systemic (not restricted to initial infection site
- has memory (recognizes + mounts stronger attack on previously encountered pathogens)
types of immunity
lymphocytes act directly (lysing foreign cells) or indirectly (releasing chemicals that enhance IR or activate other immune cells)
humoral (antibody-mediated) immunity
indirect
cells produce chemicals (antibodies) for defense and release them into body fluids (humors)
cellular/cell-mediated immunity
direct
lymphocytes defend body by targeting virus infected cells + cancer cells + cells of foreign grafts
nonself antigens
non-self
usually proteins or polysaccharides
capable of exciting immune system + provoking immune response
examples of common non-self antigens
foreign proteins, nucleic acids, large carbs, some lipids, pollen grains, microorganisms (bacteria, fungi, virus particles)
self antigens
human cells have many surface proteins which are self antigens
immune cells do not attack these but our cells in other can provoke response
restricts donors for transplants (special drugs needed to stifle immune response)
haptens/incomplete antigens
small molecules that are not antigenic, but may link up with our own proteins
protein-hapten complex
forms when haptens join with proteins (maybe antibodies)
immune system may recognize and respond to this by stimulating antibody production + reactive T cells
harmful because it attacks own cells (allergies)
chemicals that act as haptens
certain drugs
poison ivy
animal dander
detergens, hair dyes, cosmetics, household/industrial products
penicillin reaction
most common drug hapten provoking immune response (binding of penicillin to blood proteins)
causes a reaction on some
in some cases, immune system is so triggered that person’s life may be in danger
