Communicable diseases Flashcards
Examples of
Bacteria
Virus
Protoctista
Fungi
TB, bacterial meningitis, ring rot
HIV/AIDS, influenza, tobacco mosaic virus
Malaria, potato blight
Black sigatoka, ring worm, athelets foot
Pathogenic modes of action
Damaging host directly
Virus takes over cell - inserts viral DNA/RNA into hosts DNA
= new viruses made
Virus bursts = spreads to other cells
Cell dies
Producing toxins
Bacteria/ fungi produces toxins - damage host
Types of direct and indirect transmission - animals + plants
Direct contact, ingestion, inoculation
Fomites, droplet infection, vectors
Direct contact of healthy plant with diseased plant
Soil contamination, vectors(spores carried by wind, water or animals)
Physical + chemical defences of plants
Callose synthesis
Cellulose cell wall - barrier
Waxy cuticle - prevent water collecting on surface
Bark
Stomatal closure - prevent possible entry of pathogen
Insect repellent
Insecticides
General toxins
Callose deposition - physical defence of plant
Receptors activated by pathogen
Triggers production of secondary messengers
Nucleus produces molecules to directly attack pathogen
+ Callose to block plasmodesmata = strengthen cell wall + prevent pathogen moving to next cell
Primary defences
Skin - prevent entry + sebum = prevents pathogen growth
Mucous membranes - traps microorganisms + contain lysosomes
Acid in stomach - denatures pathogens
Blood clotting
Wound repair
Inflammation
Expulsive reflexes
Inflamatory response
Localised response to pathogens
Mast cells release histamines + cytokines
Histamines = dilation blood vessels - causes localised heat + redness
Raised temp = prevents pathogen reproduction
Makes blood vessels more leaky = tissue fluid formation = oedema
Cytokines = attract phagocytes - phagocytosis
Fevers + Phagocytosis
Cytokines = reset thermostat in hypothalamus
To above 37 - pathogens unable to reproduce
Pathogen produce chemicals - attract phagocyte
Phagocyte recognises non-self antigen on pathogen
Phagocyte engulfs pathogen in phagosome
Lysosome fuses with phagosome = phagolysosome
Pathogen = digested
Process of antigen presenting cell
Macrophages
Combines antigens of pathogens with MHC (type of glycoprotein)
Forms APC
Opsonins
Bind to antigen on pathogen + help binding to phagocyte
Increase recognition to phagocytes
Agglutinins
Clump pathogens
Prevents pathogens from moving + reproducing
Helps phagocytes engulf by phagocytosis
Clonal selection
Activation of specific B or T cells
Clonal expansion
Increase in the umber of cells by mitotic division
2 types of cells B lymphocytes develop into
Plasma cells = manufacture antibodies
B memory cells = provide long term immunity
4 types of cells T lymphocytes develop into
T helper cells = release cytokines, helps B cells to develop
T killer cells = attack + kill host cells that display foreign antigens
T memory cells = long term immunity
T regulator cells = shut down immune response after pathogen has been removed
