module 4: pathogens and disease Flashcards
bacterial diseases
animals- TB
humans- bacterial meningitis
pots/toms- ring rot
viral diseases
animals-influenza
human- HIV/AIDS
plants- tobacco mosaic virus
fungal diseases
animals- ringworm
human- athletes foot
plants/bananas- black Sigatoka
protoctist diseases
animals/humans- malaria
pots/toms-pot/tom late blight
direct transmission
from one organism to another e.g. droplet, sex, touching
indirect tranmission
from one to another via intermediate e.g. air, water, vector
factors affect transmission
overcrowding, climate, human social factors
inflammation
triggered by tissue damage, the damaged tissues release histamines which increase permeability of the blood vessels so they leak fluid into surrounding area and isolate pathogens due to swelling, histamines cause vasodilation to increase blood flow bringing white blood cells to area
blood clotting
thrombin activates fibrinogen to fibrin which forms a network of fibres to form and trap platelets blood cells so platelets can form scab
wound repair
outer layer of skin cells divide, tissue below wound contracts to bring edges together, repaired using collagen fibres
primary barriers in animals
skin, mucous membranes, blood clotting, inflammation, wound repair, expulsive reflexes
plant physical defences
waxy cuticle, cell walls, calls produced in times of stress
plant chemical defences
saponins- destroy pathogen cell membranes
secrete toxic chemicals to predators
four stages in immune response
1- phagocyte engulfs pathogen
2- phagocytes activate T lymphocytes
3- T lymphocytes activate B lymphocytes to produce plasma cells
4- plasma cells make more antibodies to specific antigen
phagocytosis
phagocyte recognises pathogen
phagocyte engulfs pathogen so it is now in phagosome
a lysosome fuses with phagosome to break down pathogen
phagocyte presents antigens become APC
activate T lymphocytes- clonal selection
surface covered in receptors which complementary antigens bind to
divides into t helper cells, t killer cells and t regulatory cells and t memory cells
active B lymphocytes- clonal expansion
covered in antibodies than bind to antigen to form antigen-antibody complex, this actives B cell to form plasma cells and memory cells
structure of anti body
heavy chains at bottom, light chains at top, variable regions at ends that specific to antigen, disulphide bridge holds heavy chains together
agglutination
clump pathogens together as antibodies have two binding sites so phagocytes can engulf many at once
neutralising toxins
have anti toxins that bind to toxins produced by pathogens which prevents them effecting human cells
preventing pathogen binding
when antibodies bind to antigens, antigens can’t bind to human cells so it can’t infect host cells
active immunity
immune system makes own antibodies after antigen stimulation
natural- catching disease
artificial- vaccination
passive immunity
given antibodies made by different organism
natural- baby immune from breast milk as receives antibodies from mother
artificial- immune after injection of antibodies from someone else
