Communicable diseases, disease prevention and the immune system Flashcards
what is a pathogen?
Microorganism that causes disease
Lives in hosts
what is a communicable disease?
Any disease transmitted from one person or animal; contagious
4 groups of microorganisms
Bacteria
Fungi
Viruses
Protoctista
Diseases caused by bacteria
Tuberculosis
Bacterial meningitis
Ring rot in plants
Diseases caused by viruses
HIV/ AIDS
Influenza
Tobacco mosaic virus
Diseases caused by fungi
Black sigatoka
Ringworm
Athletes foot
Diseases caused by protoctista
Malaria
Potato/ tomato blight
Prokaryotic pathogens
Bacteria
Eukaryotic pathogens
Fungi
How do bacteria damage hosts?
Multiply rapidly
Damage cells by releasing waste products and/or toxins
How do fungi damage hosts?
Hyphae release extracellular enzymes e.g. celluloses to digest plant tissue
Causes decay and leaf death —> no photosynthesis
May produce toxins
Are viruses eukaryotic or prokaryotic?
Neither; they’re dead
How do viruses damage hosts?
Invade living cells where genetic material in virus takes over the biochemistry of the host cells
Makes more copies
Host cell bursts, releasing viruses
what are Bacteriophages?
Viruses that can attack bacteria
How do protoctista damage hosts?
Enter host cells and feed on contents before breaking over cells
How may protoctista enter through the body directly?
Polluted water
what is Transmission?
Passing a pathogen from an infected individual to an uninfected individual
what is Direct transmission?
Passing a pathogen from host to new host, with no intermediary
what are types of direct transmission?
Physical contact: touching an infected person
Touching contaminated surfaces
Exchanging bodily fluids
Faecal - oral transmission: eating food or drinking water contaminated by pathogen
Droplet infection: pathogens are carried in tiny water droplets in the air
Spores: are the resistant stage of some pathogens
Can be carried in the air or reside on surfaces or in the soil
what is Indirect transmission?
Pathogens are transmitted indirectly via a vector
what is a Vector?
Another organism that may be used by the pathogen to gain entry to the primary host
what is a cause of malaria?
Plasmodium parasite
It enters the human host via a bite from a female Anopheles mosquito
what social factors affect direct transmission?
Overcrowding Poor ventilation Poor sanitation Poor health - likely to contract other diseases Poor diet (malnutrition) Lack of education
Why is there a greater variety of diseases to be found in warmer climates?
Many protoctists, bacteria and fungi can grow and reproduce more rapidly in warm and moist conditions
Why are plants targets for microorganisms?
Manufacture sugars in photosynthesis and convert this into wide variety of compounds such as proteins and oils - rich source of nutrients for microorganisms
how is the skin a primary, non-specific defence?
physical/ chemical barrier
secretes sebum- creates acidic environment so pathogens cant colonise
secrete lysozymes- catalyses the breakdown of carbohydrates in cell walls of bacteria
describe mucus membranes
pathogens breathed in get trapped in mucus lining the lung epithelium
cilia wafts the mucus up the trachea to the throat- swallowed and goes to stomach where its killed
what happens during blood clotting?
they’re formed by series of chemical reactions that take place when platelets are exposed to damaged blood vessels