4 - disease Flashcards
pathogen
ORGANSIM THAT CAUSES DISEASE
bacteria
– tuberculosis (TB)
- bacterial meningits
- ring rot (potatoes, tomatoes)
viruses
HIV/AIDS (human)
infuenza (animals),
Tobacco Mosaic Virus (plants)
protoctista
malaria
potato/tomato late blight
fungi
black sigatoka (bananas)
ringworm (catle)
athlete’s foot (humans)
direct transmission examples
direct physical contact
faecal/oral transmission
droplet infection
transmission by spores
indirect transmission
vector - another organism that may be used by pathogen to enter primary host
outer defences plant
bark - physical barrier
waxy cuticle - prevents water from building up
stomatal closure - guard cells close if pathogen is present
transport tissue defenses
the phloem can be blocked - callose blocks the sieve plate
xylem can be blocked - tylose are like balloons that swell up and block tube
celllular level defenses
the cellulose cell wall is a physical barrier - that can be thickens and strengthened (active)
lignification - waterproofs and strengthens the cell
callose deposition in the plasmadesmata - physical barrier to defenses
chemical plant defenses
terpenoids - menthol in mint
phenols - damage microorganisms
alkaloids - caffeine nic coke morphine
defensive proteins
hydrolytic enzymes - chitinase glucanases
necrosis
infection occurs,
cells around pathogen die and this
decreases water avalibilty
decreases nutrition availibilty to pathogen
like cankers
primary defence
prevents entry of pathogens
secondary defences
counteract pathogens when they have entered
skin
physical barrier
keratinocytes
top layer of skin
dead skin cells
blood clotting
in damaged skin vessels the platelets are exposed to collagen
triggers clotting response
fibrinogen (soluble) turned into fibres (insoluble)
mesh of fibres traps cells - stops bleeding and entry of pathogens
trachea mucus defense
traps pathogens
ciliated epithelial cells waft mucus up and out of trachea
mucus is swallowed
pathogens destroyed by hcl in stomach
coughing and sneezing
expulsion of pathogen with air
inflammation
pathogen detected by mast cells
mast cells releases histamines
histamine causes vasodilation and make blood vessels more permeable
more tissue fluid is formed leads to swelling (oedema)
more blood flow =redness
= more phagocytes
in the area
more permeable walls =
more phagocytes into the tissue
tissue fluid containing pathogens and phagocytes drains to lymphnodes where there are lymphocytes
describe how a neutrophil works?
receptors on the surface of neutrophil bind to antigens on pathogens
pseudo pods extend and surround pathogen . pathogen is engulfed
pathogen is contained in a large vessicle called a phagosome
phagosome is fused w lysosome
enzymes digest pathogen
once its done this many times it will die
shown as pus
describe how macrophages work
travel in the bloodstream as monocytes - only become macrophages when reach tissues
pathogen is engulfed
contained in a phagosome. fised with with a lysosome
enzymes digest pathogen but antigens on surface of pathogen are retained
antigens are combined w proteins to form major histocompability complexes
complexes moved to cell surface of macrophage makes it an antigen presenting cell
this allows antigen to be identified by other immune cells and prevents it from being attacked by other immune cells
