Fighting Disease Flashcards
What are the two main types of Pathogen?
Bacteria and Viruses
Bacteria are very small living cells which reproduce rapidly inside your body. They make you ill by damaging your cells and producing toxins.
Viruses are Not cells, they are tiny.
They replicate themselves by invading cells and using the cells machinery to produce many copies of themselves.
The cell will usually then burst realising the new viruses. The cell damage is what makes you ill
How does your body defend itself against disease?
Skin, hairs and mucus in your respiratory tract stop many micro organisms getting inside your body.
Platelets clot blood quickly to seal wounds so that microorganisms cant get into the body through cuts as easily - blood will clot slower if you have low numbers of platelets.
How do White blood cells help defend against microbes?
White blood cells travel around in blood, crawl into every part of you and constantly patrol for microbes. When they come across invading microbes they..
• Engulf foreign cells with antigens on the surface and digest them
• When white blood cells come across foreign antigens they start to produce antibodies to lock on and kill foreign cells - antibodies produced are specific to that antigen and won’t lock onto any others.
• Antibodies produce rapidly and are carried around the body to kill all similar bacteria or viruses.
• If the person is infected again with the same pathogen white bloody cells will rapidly produce the antibodies to kill it. The person is naturally immune to that pathogen and won’t get ill.
How do Vaccinations help fight disease?
Vaccinations involve injecting small amounts of dead or inactive microorganisms carrying antigens which cause your body to produce antibodies to attack them. The microbe is harmless since it’s dead.
After that, if live microorganisms of the same type appear the white blood cells can rapidly mass produce antibodies to kill off the pathogen.
What are booster injections for?
Some vaccinations wear off over time so booster injections may need to be given to increase levels of antibodies again
Pros & Cons of vaccinations?
Pros:
• They have helped control lots of infectious diseases that were once common. e.g polio, measles, whooping cough, rubella, mumps, tetanus. Smallpox no longer occurs at all and polio infections have fallen by 99%.
• Epidemics can be prevented if a large percentage of the population are vaccinated. People who aren’t vaccinated are then very unlikely to catch the disease.
Cons:
•Vaccines don’t always work - sometimes don’t give you immunity.
• Can sometimes have bad reactions to vaccines (swelling, fever or seizures) but bad reactions are very rare.
How do Antibiotics work?
Antibiotics actually kill the bacteria causing the problem without killing your own body cells. Different antibiotics kill different types of bacteria so it’s important to be treated with the right one.
Antibiotics however don’t kill VIRUSES due to the fact they reproduce using your own body cells which makes it very difficult to kill just the virus and not body cells.
How can bacteria become resistant to antibiotics?
Bacteria can mutate and cause them to be resistant to antibiotics.
Some bacteria in an infection can be resistant to antibiotics, meaning when you treat an infection, only the non resistant strains of bacteria will be killed.
Individual resistant strains will survive and reproduce, the population of the resistant strain will increase.
The resistant strain could cause serious infection that can’t be treated by antibiotics.
**to slow down the rate of development of resistant strains doctors should only prescribe antibiotics for more serious things and not for things like sore throats.
How can you investigate the action of Antibiotics or Disinfectants?
By growing cultures of microorganisms in agar jelly containing carbohydrates, minerals, proteins and vitamins.
Hot agar jelly is poured into plastic dishes called Petri Dishes. When it’s set, wire loops are used to transfer microorganisms to the culture medium, microbes then multiply.
Paper discs soaked in different types of antibiotics are placed on the jelly. Antibiotic resistant bacteria will grow around them but non resistant strains will die.
Why is medium culture equipment sterilised?
To Prevent Contamination
If it isn’t sterilised unwanted microorganisms will grow and affect the result.
Petri dishes, culture medium and inoculating loops must be must be sterilised before use.
Inoculating loops are sterilised by passing them through a flame.
The Petri dish must also have a lid to stop any microorganisms in the air contaminating the culture. The lid should be taped.
