M4 CH12 disease Flashcards
state and explain the 4 fist lines of defence (non specific)
1.) skin:
- physical barrier
- sebum: sebum on surface of skin: slightly acidic so prevents growth of bacteria
2.) mucous membranes:
- secrete mucus to trap pathogens
- found in airways (nose/trachea)
3.) expulsive reflexes:
- coughing/sneezing, triggered when mucus memb is irritated
4.) chemical secretions:
- lysozymes: breakdown bacteria cell walls, found in tears
- hydrochloric acid, found in stomach
state and briefly outline the 4 second lines of defence. (not 1st and 4th)
1.) blood clotting
- cascade effect
2.) inflammation:
-swelling isolates pathogen
- vasodilation brings WBCs to infection site
- stimulated by cytokines
3.) wound repair:
- skin cells divide and migrate to edges of wound
- tissue under skin pulls inwards to close cut
4.) phagocytosis
draw and explain the cascade effect showing how a blood clot is formed
mark diagram using blue notebook (no 2)
1. thromboplastin catalyses conversion of prothrombin into thrombin
2. thrombin catalyses conversion of fibrinogen into fibrin
3. fibrin becomes clot
outline the key features of bacterial pathogens, and give 3 examples of communicable diseases caused by bacteria.
- prokaryotic
- no membrane bound organelles or DNA
- peptidoglycan cell wall (gram + has thicker C.W than gram -)
- circular DNA
- tuberculosis & bacterial meningitis (animal diseases)
- ring rot (plant disease)
outline the key features of fungal pathogens, and give 3 examples of communicable diseases created by fungal pathogens.
- eukaryotic
- can be mcellular OR ucellular
- chitin cell wall
- releases spores to spread disease
- athletes foot, ringworm (animal)
- black sigatoka (plant)
outline the key features of viral pathogens, and give 3 diseases caused by them.
- non living
- genetic information contained in capsid
- contain attachment proteins
- can only reproduce inside hosts
- HIV, influenza (animal)
- tobacco mosaic virus (plants)
outline the key features of protista pathogens, and state 3 diseases they cause.
- eukaryotic
- unicellular
- cellulose cell walls
- malaria (animal)
- potato blight (plant)
- tomato blight (animal)
state and explain the 3 types of direct transmission of disease in humans.
- direct contact:
- kissing, contamination of bodily fluids (STIs), skin to skin contact (ringworm/athletes foot) - inoculation:
- entering of disease through a break in the skin. e.g animal bite, puncture wound, needle sharing - ingestion:
- through contaminated food or drink
- contamination from hand to mouth (diarrhoeal diseases)
state and explain the 2 types of indirect transmission of disease in humans.
- droplet infection:
- coughing/sneezing
- e.g. TB, influenza - vectors:
- typically animals- mosquitoes & malaria
- can be water: diarrhoeal diseases
outline how plant diseases are transmitted directly (1) and indirectly (2)
direct:
- direct contact between plants (could be due to close planting from overcrowding)
- e.g. tmv, ringrot, black sigatoka
indirect:
1. soil contamination:
- infected plants leave pathogens/spores in the soil (pathogens: bact/viruses) (spores: fungi/protoctista)
2. vectors
- wind: spread of spores
- water: spores swim on surface film water on leaves (e.g. p blig’)
- animals: carried by insects/birds
- humans: clothing/fomites/ transportation of plants
outline the factors affecting transmission of plant diseases
(5)
- planting variety: some are more/less susceptible to disease.
- plant overcrowding: increases direct contact/transmission
- poor mineral nutrition: reduces plant resistance to disease
- damp/warm conditions: increases survival and spread of pathogens
- climate change: increase wind (spread of spores more)
or drier conditions: reduces disease transmission
outline the main physical defence used by plants, and how it works to prevent the spread of the pathogen.
(4)
callose: polysaccharide
- plant detects attack, and callose is deposited between cell walls and cell membranes in cells next to infected ones
- large amounts of callose continue to be deposited, lignin added to increase strength. acts as barriers, preventing entering of pathogen to infection site.
- callose blocks sieve plates in phloem, sealing off the affected part and preventing spread of the pathogen.
- callose also deposited in plasmodesmata between infected cells and their neighbours- sealing off from the healthy cells.
outline the chemical defences in plants, and what they each provide protection from.
(6)
- phenols: antibacterial and antifungal compounds
- intesecticides: pyrethrins, act as insect neurotoxins
- insect repellents: cintronella & pine resin
- defensins: proteins that disruot bacterial and fungal cell membranes
- chitinases: enzymes that breakdown chitin in fungal cell walls
- saponins: found in plant cell membrane, interferes with fungal cell membranes
- glucanases: enzymes that breakdown polymers found in cell walls of oomycetes (fungi like micro organsim)
outline the factors that affect the transmission of communicable diseases in animals.
- overcrowded living/ working conditions
- poor nutrition
- poor waste disposal (breeding sites for vectors)
- climate change (temp increase promotes bacteria growth)
- cultures: some traditional medical practices can increase transmission
- socio-economic factors: lack of trained health workers, insufficient public knowledge and warning about disease/spread
explain the role of mast cells in the inflammatory response (second line of defense)
- activated in damaged tissue
- release histamines and cytokines.
histamines::
-> cause vasodilation which causes localised heat and redness. raised temperature helps prevent reproduction of pathogens
-> make blood vessel walls more leaky: blood plasma forced out forming tissue fluid (swelling)
cytokines:
-> attract white blood cells: phagocytes to the site
-> phagocytosis takes over process
