Topic 3 - Infection and Response Flashcards
What are pathogens?
Microorganisms that enter the body and cause communicable diseases
Can pathogens only infect animals?
No they can infect plants too
What are the different pathogens?
Bacteria
Viruses
Protists
Fungi
What are bacteria?
Very small cells about 1/100 th the size of our body cells.
How do bacteria make us feel ill?
By producing toxins that damage your cells and tissues. They reproduce rapidly in the body
What are viruses?
They are not cells. They are about 1/100 th the size of bacterium.
How do viruses make us feel ill?
They live inside your cells and use the cells machinery to produce many copies of themselves, the cell will burst, releasing all the new viruses. The cell damage is what makes you feel ill
What are protists?
They are eukaryotes and most of them are single-celled. Some are parasites.
What do parasites do?
Live on it inside other organisms and can cause them damage, they are often transferred to the organisms via a vector which doesn’t get the disease itself.
What are fungi?
Some are single-celled. Others have bodies made of hyphae (thread like structures)
How do fungi make us feel ill?
Hyphae from the fungi can grow and penetrate human skin and the surface of plants, causing disease. Hyphae can produce spores which can be spread to other plants and animals.
How do pathogens spread?
Water
Air
Direct contact
How do pathogens spread through water?
Some can be picked up by drinking and bathing in dirty water. E.g. cholera is a bacterial infection that’s spread by water contaminated with diarrhoea from other sufferers
How do pathogens spread through air?
They can be breathed in through the air. Some are carried in air born droplets produced when you cough or sneeze. E.g. the influenza spreads this way.
How do pathogens spread through direct contact?
Some pathogens can be picked up by touching contaminated surfaces, including the skin. E.g. athletes foot is a fungus which makes skin itch and flake off, most commonly spread by touching the same things as the contaminated
What are 3 viral diseases that we need to know?
Measles
HIV
tobacco mosaic virus (TMV)
How is measles spread?
By droplets from an infected cough or sneeze
What is measles?
Red skin rash and signs of fever. It can be very serious and even fatal if there are complications. Most people are vaccinated against measles when they are young
What are the complications of measles?
Pneumonia (lung infection)
Encephalitis (brain infection)
How is HIV spread?
Sexual contact or by exchanging bodily fluids like blood, this can happen when people share needles when taking drugs
What are the symptoms of HIV?
Flu- like symptoms for a few weeks, then no symptoms for several years. Viruses attack immune cells, if the body’s immune system is badly damaged it can’t cope with other infections or cancers. At this point it has become AIDS
How can HIV be treated?
When there are no symptoms for years during this time HIV can be controlled with antiretroviral drugs which stop the viruses replicating
What is tobacco mosaic virus?
A virus that affects many species of plants, it causes a mosaic pattern on the leaves of the plants, parts of the leaves become discoloured. Discolouration means less photosynthesis so the virus affects growth
what is rose black spot?
a fungus that causes purple or black spots to form on the leaves of rose plants, less photosynthesis can happen so the plant doesn’t grow very well
how does rose black spread?
though the environment in water or by the wind
how can rose black spot be treated?
gardeners can treat the disease using fungicides and by stripping the plant of its affected leaves, these leaves then need to be destroyed so that the fungus an’t spread
what is malaria?
its caused by a protist, mosquitoes are vectors when they pick it up from feeding on infected animals. whenever the mosquitoes feed on another animal they insert the protist into the animal’s blood vessels
what are the symptoms of malaria?
it causes repeating episodes of fever, it can be fatal
how can malaria be prevented?
the spread of malaria can be reduced by stopping the mosquitoes from breeding. people can be protected using insecticides, mosquito nets and being vaccinated against it
what are 2 bacterial diseases?
salmonella
gonorrhoea
what is salmonella?
its a type of bacteria causes food poisoning
what are the symptoms of salmonella?
fever, stomach cramps, vomiting and diarrhoea. these symptoms are caused by toxins that the bacteria produce
how do people get salmonella?
eating food thats been contaminated with salmonella bacteria, e.g. eating chicken that was contaminated whilst it was alive, or food prepared in unhygienic conditions
how can salmonella be prevented?
in the UK, most poultry is given a vaccination against salmonella, this is to control the spread of the disease
what is gonorrhoea?
it is a sexually transmitted disease, which is spread through sexual contract, and is caused by bacteria
what are the symptoms of gonorrhoea?
pain when urinating, thick yellow / green discharge from the penis or vagina
how can gonorrhoea be treated?
it was originally treated with an antibiotic called penicillin, but this is trickier because certain strains have become resistant. to prevent the spread people can be treated with antibiotics and should use barrier methods of contraception such as condoms
what can be done to reduce and prevent the spread of disease?
being hygienic
destroying vectors
isolating infected individuals
vaccination
how can being hygienic reduce the spread of disease?
using simple hygiene measures can prevent the spread of disease. e.g. washing hands thoroughly before preparing food after you have sneezed can stop you infecting another person
how can destroying reduce the spread of disease?
by getting rid of the organisms that spread disease, you can prevent the disease from spreading. insect vectors can be destroyed with insecticides or destroying habitats so they can’t breed
how can isolating infected individuals reduce the spread of disease?
if you isolate someone with a communicable disease, it prevents them from passing it on to anyone else
how can vaccination reduce the spread of disease?
vaccinating people and animals means they can’t develop the disease and pass it on to someone else
what defends the body against disease?
skin tears earwax mucus stomach acid if none of these work the immune system kicks in