Disease and the immune system Flashcards
What is a pathogen and what are its four types b
An organism that causes disease. Bacteria, viruses, fungi and protoctista.
What diseases does bacterium cause?
TB, Bacterial meningitis and ringrot
What diseases does virus cause?
HIV/AIDS, Influenza and Tobacco mosaic virus
What diseases does fungus cause?
Black Sigatoka, ringworm and athletes foot
What diseases does protoctist cause?
Potato/tomato blight and malaria
What are the two ways to spread a communicable disease?
Direct and indirect transmission
What is direct transmission? How?
A disease is transmitted directly from one organism to another.
Droplet infection, sexual intercourse or touching
What is indirect transmission? How?
When disease is transmitted from one organism to another via an intermediate.
Air, water, food or another organism (vector)
Name two diseases spread by direct transmission
HIV (sex) and Athletes foot (touch)
Name two diseases spread by indirect transmission
Potato blight (spores) and malaria (vectors(mosquitoes))
What three factors can affect disease transmission?
1) Living conditions
2) Climate
3) Social factors
How can living conditions affect disease transmission?
Overcrowded conditions can increase transmission - droplets in air remain for long periods of time
How can climate affect disease transmission?
1) Malaria more common in hot countries
2) Potato blight common during wet summers because spores need water to spread
How can social factors affect disease transmission?
1) Good health education means that people are informed about how it is transmitted and how it can be avoided
2) Good healthcare means there are more treatment options available
What barriers do animals have to prevent infection?
1) Skin
2) Mucous membranes
3) Blood clotting
4) Inflammation
5) Wound repair
5) Expulsive reflexes
How is skin a barrier to prevent infection?
Physical barrier that blocks pathogens from entering
How are mucous membranes a barrier to prevent infection?
Sticky substance trap pathogens
How is blood clotting a barrier to prevent infection?
Plug wounds to prevent pathogen infection
How is inflammation a barrier to prevent infection?
Swelling helps to isolate pathogens and increase blood flow to the area, bringing WBC
How is wound repair a barrier to prevent infection?
Skin reforms to prevent pathogen entry
How is expulsive reflexes a barrier to prevent infection?
Coughs and sneezes expel foreign objects
What barriers do plants have against pathogens?
1) Waxy cuticles provide a physical barrier
2) Plant cell walls provide a physical barrier
3) Callose (a polysaccharide) gets deposited at the plasmodesmata to limit spread of virus between cells
4) Antimicrobial chemicals kill pathogens
5) Chemicals secreted by plants toxic to insects
6) Pheromones can tell other plants to protect themselves and produce toxic chemicals
What are the four main stages in the immune response!
1) Phagocytes engulf the pathogen
2) Phagocytes activate T lymphocytes
3) T lymphocytes activate B lymphocytes which divide into plasma cells
4) Plasma cells make more antibodies to a specific antigen
What is a phagocyte?
A type of WBC that carries out phagocytosis
How does a phagocyte engulf a pathogen?
1) Phagocyte recognises the antigens on a pathogen
2) Cytoplasm moves round the pathogen and engulfs it
3) Pathogen is now contained in a phagosome
4) lysosome containing digestive enzymes breaks down the pathogen
5) phagocyte presents pathogens antigens to active other immune system cells