factors affecting disease transmission and defense against pathogens

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name three things that can increase the transmission of communicable diseases?
overcrowded living conditions, climate, social factors ,(in humans).
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give an example to describe how overcrowded living conditions can affect transmission of communicable diseases?
TB is spread directly by droplet infection. also spread indirectly as the bacterium can remain in the air for long periods of time. so crowded living conditions increases the risk of infection.
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give two examples of how climate can increase the risk of transmission of communicable diseases.
potato/tomato late blight is esspecially common in wet summers because the spores need water to spread. malaria is most common in tropical countries, ideal conditions for mosquitoes to breed as its humid and hot.(malaria vectors.)
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give two examples of how social factors in humans can increase the risk of transmission of communicable diseases.
HIV infection risk is higher in places with limited access to good health care or limited education on safe sex. This is because people are less likely to be diagnosed and also don't have the best anti-HIV drugs available to them .
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how does skin act as a primary non-specific defense?
acts as a physical barrier, blocking pathogens from entering body. can also act as a chemical barrier by producing chemicals that are antimicrobial , lowers Ph, inhibiting growth of pathogens.
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how do mucus membranes act as a primary non-specific defense?
protect body openings that are exposed to the environment. some membranes trap pathogens by secreting mucus that contains antimicrobial enzymes.
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explain how blood clots act as a primary non-specific defense against pathogens and how they're formed?
mesh of protein fibres plug wounds to stop pathogens from entering body, or blood being lost. formed by a series of chemical reactions that occur when platelets are exposed to damaged blood vessels.
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what are 4 signs of inflammation?
swelling, pain, redness or heat.
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what is inflammation triggered by?
damaged tissue releases molecules which increase the permeability of the blood vessels, so they start to leak fluid into the surrounding area.
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how does inflammation act as a primary non-specific defense against pathogens?
swelling caused helps to isolate any pathogens that may have entered the damaged tissue. vasodilation also enables an increased blood flow,(heat), bringing an increased amount of white blood cells with it too fight any pathogens found.
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how do wounds repair and why does this act as a non-specific defense against pathogens?
wound repair re-forms a barrier against pathogens in the event of injury. surface of wound is repaired by outer layer of skin cells dividing and migrating to edges. tissue below contracts pulling edges closer and collagen fibres finish the repair.
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what are expulsive reflexes?
coughing and sneezing.
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why do we sneeze?
a sneeze happens when the mucus membranes in the nostrils are irritated by things such as dust or dirt.
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why do we cough?
a cough stems from irritation in the respiratory tract.
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why do expulsive reflexes act as a primary non-specific defense against pathogens?
coughs and sneezes are attempts to expel foreign objects, including pathogens, from the body. They're automatic.
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what happens if pathogens get pass primary non-specific defenses?
They then have the immune system to deal with.
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how do plants defend themselves against pathogens with waxy cuticles?
stems and leaves waxy cuticles provide a physical barrier against pathogen entry and also stop water collecting on leaves reducing the risk of infection by pathogens transferred between plants by water.
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how do plants defend themselves against pathogens with cell walls?
form a barrier against pathogens that make it past the waxy cuticle.
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plants produce a polysaccharide called callose in times of stress, like pathogen invasion, explain how this helps?
callose deposition in plant cell walls and membranes makes it harder for pathogens to enter cells. callose deposited at the plasmodesmata may also limit the spread of viruses between cells.
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what are the plasmodesmata in plants?
small channels in their cell walls.
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plants also defend themselves against pathogens using chemicals, what are these chemicals and what do they do?
produce antimicrobial chemicals, including antibiotics, which kill pathogens or inhibit their growth.
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give two chemicals that plants can create to defend themselves against pathogens and what they do?
some plants make chemicals called saponins- thought to destroy cell membranes of fungi. chemicals called phytoalexins inhibit the growth of fungi and other pathogens.
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how do plants secreting chemicals toxic to insects help them defend themselves against pathogens?
this reduces the amount of insects feeding on plants which therefore reduces the risk of infection by plant viruses carried in insect vectors.
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Card 2

Front

give an example to describe how overcrowded living conditions can affect transmission of communicable diseases?

Back

TB is spread directly by droplet infection. also spread indirectly as the bacterium can remain in the air for long periods of time. so crowded living conditions increases the risk of infection.

Card 3

Front

give two examples of how climate can increase the risk of transmission of communicable diseases.

Back

Preview of the front of card 3

Card 4

Front

give two examples of how social factors in humans can increase the risk of transmission of communicable diseases.

Back

Preview of the front of card 4

Card 5

Front

how does skin act as a primary non-specific defense?

Back

Preview of the front of card 5
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