Infection And Response Flashcards
1
Q
What is a pathogen
A
- microorganisms that enter our body and cause disease
- cause communicable (infectious) diseases
- both plants and animals can be affected by pathogens
2
Q
What are bacteria
A
- very small cells which can reproduce rapidly inside our bodies
- they can make us feel ill by producing toxins that damage our cells and tissues
3
Q
What are viruses
A
- they’re not cells
- they’re tiny
- like bacteria, they reproduce rapidly inside our bodies
- they live inside our cells and replicate themselves using the cells’ machinery to make copies of themselves. The cell will usually burst, releasing all the new viruses
- this cell damage is what makes you feel ill by producing
4
Q
What are protists
A
- single-cell eukaryotes
- some are parasites
5
Q
What are parasites
A
(Protists)
- live on or inside other organisms and can cause them damage
- often transferred to the organism by a vector, which doesn’t get the disease itself (eg. An insect carries the protist)
6
Q
What is fungi
A
- some are single-celled
- some have a body made up of hyphae
- these hyphae can grow and penetrate human skin and the surface of plants, causing diseases
- the hyphae can produce spores, which can be spread to other plants and animals
7
Q
How are pathogens spread
A
- air
- water
- direct contact
8
Q
How are pathogens spread by water
A
- drinking or bathing in dirty water
- eg. Cholera, bacterial infection thats spread by drinking contaminated water
9
Q
How are pathogens spread by air
A
- carried through air and breathed in
- some pathogens are carried in the air in droplets produced wen you cough or sneeze
- eg. Influenza virus that causes flu is spread this way
10
Q
How are pathogens spread by direct contact
A
- touching contaminated surfaces, including skin
- eg. Athletes foot is a fungus which makes skin itch and flake off: spread by touching infected person like shower floors and towels
11
Q
3 viral diseases
A
- measles
- HIV
- tobacco mosaic virus
12
Q
2 bacterial diseases
A
- salmonella
- gonorrhea
13
Q
Fungal disease
A
- rose black spot
14
Q
Protist disease
A
Malaria
15
Q
Measles
A
- viral
- spread by droplets from an infected persons sneeze or cough
- infected person: red skin rash, signs of fever
- can be serious or fatal
- can lead to pneumonia or inflammation to brain
- most people are vaccinated from it when they’re young
16
Q
HIV
A
- virus
- spread through sexual contact or exchanging bodily fluids like blood (share needles when taking drugs)
- flu-like symptoms for a few weeks
- usually doesn’t then experience for several years. During this time, HIV can be controlled with antiretroviral drugs: stops virus replicating in the body
- virus attacks immune cells
- if body’s immune system is badly damaged, it cant cope with other infection or cancers
- At this stage, the virus is late stage HIV infection or AIDS
17
Q
Tobacco mosaic virus
A
- virus that affects many species of plants
- causes mosaic pattern on the leaves of plants, leaves become discoloured
- this discolouration means the plant can’t carry out photosynthesis as well so the virus affects growth
18
Q
Rose black spot
A
- fungal
- causes purple or black spots to develop on leaves of rose plants
- the leaves can turn yellow and drop off
- photosynthesis cant happen, so the plant doesn’t grow very well
- spreads through environment in water or by wind
- how to get rid of it: stripping plant of affected leaves or using fungicides. Leaves have to be destroyed so it doesn’t spread to other plants
19
Q
Malaria
A
- protist
- mosquitos are vectors, pick up the protist when they feed on an infected animal
- every time the mosquito feeds on another animal, it infects it by inserting the protist into the animals blood vessels
- malaria causes repeating episodes of fever. It can be fatal
- the spread of malaria can be reduced by stopping the mosquitos from breeding
- people can be protected using insecticides and mosquito nets
20
Q
Salmonella
A
-bacteria
- causes food poisoning
- infected people suffer from fever, stomach cramps, vomiting and diarrhoea
- caused by toxins that the bacteria produce
- you get it by eating food thats been contaminated with salmonella bacteria
- in UK, most poultry is given a vaccination against it to control the spread of the disease
21
Q
Gonorrhea
A
- bacteria
- sexually transmitted disease
- passed on through sexual contact (unprotected sex)
- infected person will get pain when they pee
- another system is yellow or green from the vagina penis
- originally treated with antibiotic: penicillin
- this has become tricky as bacteria has become more resistant to it
- to prevent today: barrier methods of contraception or antibiotics
22
Q
4 ways of preventing spread of disease
A
- Being hygienic: basic hygiene such as washing your hands before preparing hands or after sneezing, covering mouth with arm when coughing or sneezing
- Destroying vectors: getting rid of organisms that spread disease prevent disease from being passed on. Use insecticides or destroy their habitats so they can no longer breed
- Isolating infected individuals: it prevents them from passing it on to anyone else
- Vaccination: means they are less likely to develop the infection and pass it on to someone else
23
Q
Human defence system
A
- skin: barrier to pathogens/ secretes antimicrobial substances that kill pathogens
- hair and mucus in nose: trap particles that could contain pathogens
- trachea and bronchi: secrete mucus to trap pathogens/ they’re lined with cilia, hair like structures, which waft the mucus up to the back of the throat where it can be swallowed
- stomach: produces hydrochloric acid, this kills pathogens that make it that far from the mouth
24
Q
Immune system
A
- if pathogens make it into body, the immune system kicks in to destroy them
- most important part are white blood cells
25
What do white blood cells do
- travel around in your blood and crawl into every part of you, constantly patrolling for microbes
- when they come across an invading microbe, they have 3 lies of attack:
1. Consuming them
2. Producing antibodies
3. Producing anti toxins
26
Consumption of microbes (white blood cells)
White blood cells can engulf foreign cells and digest them. This is called phagocytosis
27
Production of antibodies against microbes (white blood cells)
- every invading pathogen has unique molecules (antigens) on its surface
- when some types of white blood cells attack invasive come across a foreign antigen, they will produce proteins called antibodies to lock onto the invading cells so that they can be found and destroyed by other white blood cells
- the antibodies produced are specific to that type of antigen- they wont lock on to any others
- antibodies are then produced rapidly and carried around the body to find all similar bacteria or viruses
- if the person is infected with the same pathogen, again the white blood cells attack cells will rapidly produce the antibodies to kill it: the person is naturally immune to that pathogen and wont get ill
28
Production of antitoxins against microbes (white blood cells)
- these counteract toxins produced by the invading bacteria
29
What are vaccinations
- injecting small amounts of dead or inactive pathogens
- these carry antigens which cause your body to produce antibodies to attack them, even though the pathogen is harmless (since dead or inactive)
- but if live pathogens of the same type appear after that, the white blood cells can rapidly mass-produce antibodies to lock kill off the pathogen
30
Pros of vaccination
- they’ve helped control lots of communicable diseases that were once common in the uk
- smallpox no longer occurs at all and polio infections have fallen by 99%
- big outbreaks of disease (called epidemics) can be prevented if a large percentage of the population is vaccinated, that away people who aren’t vaccinated are less likely to catch it because there are fewer people able to pass it on
31
Cons of vaccination
- vaccines don’t always work, sometimes they don’t give you immunity
- you can sometimes have a bad reaction to the vaccine, but bad reactions are rare
32
What are painkillers
- drugs that relieve pain
- however, they don’t actually tackle the cause of the disease or kill pathogens,they just help reduce symptoms
33
What are antibiotics
- they actually kill or prevent growth of the bacteria causing the problem without killing your own body
- different antibiotics kill different types of bacteria so it’s important to be treated with the right one
- but antibiotics don’t destroy viruses
34
Explain bacteria becoming resistant to antibiotics
- bacteria can mutate. This can cause them to be resistant to an antibiotic
- if you have an infection, some of the bacteria might be resistant to antibiotics
- this means when you treat an infection, only non-resistant strains of bacteria will be killed
35
Resistant strain
- the individual resistant bacteria will survive and reproduce and the population of the resistant strain will increase
- the resistant strain could cause a serious infection that cant be treated by antibiotics
36
How to slow rate of development of resistant strains
- important for doctors to avoid over-prescribing antibiotic
- important that you finish a whole course of antibiotic and don’t stop just when you feel better
37
Aspirin
- used as a painkiller and to lower fever
- it was developed from a chemical found in willow
38
Digitalis
- used to treat heart conditions
- developed from a chemical found in foxgloves
39
Where did many drugs originally come from
- plants because they can produce a variety of chemicals to defend themselves against pests and pathogens
- some of these chemicals can be used as drugs to treat human diseases or relieve symptoms
- some drugs are also extracted from microorganisms
40
Drug extracted from microorganisms
- Alexander Fleming was clearing out some petri dishes contains bacteria
- he noticed one of the dishes of bacteria also had mould in it and the area around of the mould was free of bacteria
- he found that the mould on the Petri dish was producing a substance that killed bacteria
- this substance was penicillin
41
3 main steps of drug testing
1. Preclinical testing
2. Testing on live animals
3. Clinical trial
42
Preclinical testing (1)
1. Drugs are tested on human cells and tissues in the lab
2. However, you cant use human ells and tissues to test drugs that affect whole or multiple body systems
43
Animal testing (2)
1. Test drug on live animals, this is to test efficacy and to find out about its toxicity and to find best dosage
2. The law in Britain states that any new drug must be tested on 2 different live mammals:
- some people think its cruel to test on animals
- others believe its the safest way to make sure the drug isn’t dangerous before its given to humans
44
Clinical test (3)
1. If the drug passes the tests on animas then its tested on human volunteers in a clinical trial
2. First the drug is tested on healthy volunteers to aid sure it doesn’t have harmful side effects when the body is working normally
- at the start of the trial, a very low dosage of the drug is given and this is gradually increased
3. If the results are good, the drugs can be tested on people suffering from the illness. The optimum dose is found (dosage that is most effective and has few side effects)
4. To test how well it works, patients are random put into 2 groups. One is given the new drug, the other is given a placebo. This. So the doctor can see the actual difference the drug makes- it allows for the placebo effect
5. Clinical trials are blind, the patient or doctor knows whether they’re getting the real or the placebo so that the doctors analysing the results aren’t subconsciously influenced
6. The results of drug testing and drug trials aren’t published until heave been through peer review. This helps prevent false claims
45
What is the placebo effect
When the patient expects the treatment to work and so feels better, even though the treatment isn’t doing anything
46
Why do drug trials go through peer review
So there aren’t any false claims
47
Why are the doctors blind to the drug during testing
So they’re not subconsciously influenced by their knowledge
48
What is the placebo in drug trials
A substance thats like the drug being tested but doesn’t do anything
