B3 Flashcards
(23 cards)
Infections are caused when_____
A foreign pathogen invades an organism
Types of pathogens
- Viruses
- Bacteria
- Fungi
- Protists
Viruses
-tiny, non-living
-can reproduce rapidly
-they invade host cells and use them to make new virus articles
once the new viruses are made, they cause the cell to burst
-the cell damage is what makes us feel ill
Bacteria
- small, living cells
- produce toxins(poisons) that make us feel ill
- can reproduce rapidly
Fungi
- single-celled organism made up of hyphae(thread-like structures
- these hyphae’s grow and penetrate tissues
- they produce spores that can spread to other animals/plants
Protists
- single celled eukaryotic organisms
- many are parasites
- they are often transferred to the host organism by a vector such as a mosquito or insect
- they damage tissues which make us feel illl
Ways to spread diseases
- direct contact
- air
- water
Ways to prevent diseases
Destroying vectors
-by killing insects are destroying habitats
Isolation
-isolate infected individuals to stop it spreading
Hygiene
-destroy pathogens by washing them away
Vaccination
-make people immune to infection
Virus examples
Measles
- symptoms: fever, red skin rash
- can be fatal
- most people are vaccinated against it
- spread by breathing in droplets from sneezes/coughs
TMV(tobacco mosaic virus)
- affects plants such as tomatoes
- causes a mosaic pattern(discolouration)
- photosynthesis cant take place so plants growth is affected
HIV
- spread by sexual contact or exchange of bodily fluids(eg. through needles)
- symptoms= starts as flu then can cause AIDS
Bacteria examples
Gonorrhoea
- sexually transmitted
- symptoms: pain when urinating, thick yellow/green discharge
- prevented through sing contraception such as condoms
Salmonella
- causes food poisoning
- the bacteria release toxins that cause fever, stomach pain, vomiting and diarrhoea
Fungi example
Rose black spot
- can be spread through environment in water or air
- causes purple or black spots on leaves of rose plants
- leaves discolour and fall off, preventing photosynthesis
- treated by destroying/removing affected leaves
Protist example
Malaria
- spread by the female mosquito(a vector)
- the mosquito carries malaria and transfers the infection into a persons bloodstream when it bites them
- causing fevers, which can be fatal
Fighting diseases
-Non specific defences
Mucus
-traps the bacteria entering our airways
Tears
-contain enzymes that destroy pathogens
Stomach
-produces hydrochloric acid which destroys pathogens
Skin
-waterproof barrier that pathogens cannot pass through
Fighting diseases
-Immune system
1) consuming them
- A white blood cell finds the pathogen and engulfs it by changing shape
- The white blood cell absorbs and digests the pathogen, destroying it. This is called phagocytosis.
2) Producing antibodies
- White blood cells recognise foreign antigens on the surface of pathogens and produce antibodies
- Antibodies are specific to a particular pathogen
3) Producing antitoxins
- These counteract toxins produces by the invading bacteria
How does vaccination work?
- inject dead pathogen
- white blood cells recognise the foreign antigen and produce antibodies
- some of the white blood cells remain in the blood as memory cells. If the same pathogen invades again it can produce antibodies faster.
Pros/Cons of vaccination
Pros: help control diseases, large outbreaks of diseases can be prevented
Cons: don’t always work, can cause bad reactions
What do antibiotics do?
Antibiotics such as Penecillin kill bacteria
What can happen to bacteria?
How to stop resistance?
Bacteria can become resistant to antibiotics meaning they can’t be killed.
- only prescribe if needed
- patients should complete full course to ensure all bacteria are killed
What is the ‘superbug’ called? and why is it referred to as the ‘superbug’?
MRSA
because its resistant to many antibiotics
New drugs need to be tested for_____
Toxicity
-how much can be taken before side effects are too bad
Efficiency
-how well it works
Dose
-how much do you need to take
Drugs from plants
Aspirin from willow bark
Digitalis from fox glove flowers. These are a heart drug.
Penicillin is used to____
stop bacteria growth
Drug testing
- The drugs are tested on cells grown in the laboratory. This allows the efficacy and possible side effects to be tested.
- Drugs that pass the first stage are tested on animals in the second part of a drug trial.
- Drugs that have passed animal tests are used in human clinical trials. They are tested on healthy volunteers to check that they are safe. The substances are then tested on people with the illness to ensure that they are safe and that they work. Low doses of the drug are used initially, and if this is safe the dosage increases until the optimum dosage is identified.
