keeping healthy

What is a pathogen?

micro-organisms that cause infectious diseases.

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What is bacteria?

bacteria are very small cells which have no nucleus and reproduce rapidly inside your body. They make you feel ill by damaging your cells and producing toxins.

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What are viruses?

Viruses aren’t cells they are about 1/100th of a bacteria. They have no nucleus and replicate themselves by invading your cells and using the cells machinery to produce copies of themselves.

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What defence mechanisms does our body have?

The natural defences we have in our body are nose hair, mucus, skin, acid in stomach, white blood cells, eyelashes and antiseptic fluid in our eyes.

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What do platelets do?

Platelets are a small fragments of cells which help blood clot quickly to seal wounds to stop micro-organisms getting into our body. If the blood contains low numbers of platelets it will clot more slowly.

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What are antigens?

Antigens are unique molecules on its surface which invading cells have

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What happens if micro-organisms get into your body?

When White blood cells come across microbes they can engulf them and digest them. When white blood cells come across a foreign antigen they will produce antibodies to lock on to and kill the invading cell.

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continued?

Antibodies are produced rapidly and carried around the body to kill all similar bacteria or viruses.

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What happens if the pathogen enters the body again?

If the pathogen enters the body again the white blood cells produce antibodies to kill it- the person will be naturally immune to the pathogen and won't get ill.

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What are antitoxins?

These are counteract toxins which are produced by the invading bacteria.

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What happens when you have a vaccination?

A dead or inactive pathogen is inhected into the body. The White blood cells recognise that this is a pathogen and are called into action. The antibodies stick the pathogens together. They can be destroyed easily by the white blood cells.

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What happens if the pathogen enters the body again after the vaccination?

The person will be immune because the white blood cells will rapidly produce antibodies to kill off the microbes.

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What are the advantages of having vaccinations?

vaccines have helped control lots of infectious diseases which were common such as polio, measles and tetanus. Epidemics can be prevented if large percentages of the population is vaccinated. People who arent vaccinated are unlikely catch the disease

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What are the disadvantages of having vaccinations?

Vaccines don't always work- sometimes they don't give you immunity. You can sometimes have a abd reaction to a vaccine e.g swelling or something more serious like a fever or seizures although these are very rare.

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which drugs only relieve symptoms?

Some drugs such as painkillers (Aspirin) that relieve the pain. They don't actually try to tackle the cause of the disease. This is also the ame with cold medicines they only relieve symptoms.

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What do antibiotics do?

Unlike painkillers, antibiotics actually kill or prevent the growth of the bacteria without killing your own body cells. Different antibiotics kill different types of bacteria.

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How was Penicillin discovered?

Penicillin was discovered by accident in 1928 whenAlexander fleming found mould growing on a open agar plate.He observed the bacteria did not grow near the mould. The mould seemed to be making a substance that killed it.

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Why don't antibiotics destroy viruses?

Viruses reproduce using your own body cells which makes it very difficult to develop drugs that destroy the virus without killing body cells.

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Why can bacteria become resistant to antibiotics?

Antibiotics are produced by different strains of the Penicillin fungus. Bacteria are evolving all the time and are becomming resistant to antibiotics. To comba this we must always finish the course prescribed only take them when absolutely necessary.

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What is MRSA?

this resistant strain could cause a serious infection that can't be treated by antibiotics. An example of this is MRSA which causes serious wound infectious and is resistant to Methicillin.

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How does natural selection cause a population of antibiotic resistant strains of bacteria?

There is a mutation in the DNA of a bacterial cell. This causes stronger cells to survive and weaker ones to die which are stronger than antibiotics. Over the years bacterial cells are stronger.

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How do you grow Microbes in the Lab.

Microbes can be grown on agar plates using the Aseptic technique. This is a sterile method that ensures that you only grow the microbes that you require without adding contaminants.

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What is the Aseptic technique?

Micro-organisms are grown in a "culture medium" which is usually agar jelly. Hot agar jelly is oured into petri dishes. When the jelly is cooled and set the inoculating loops transfer micro-organisms to the agar jelly and the micro-organisms multiply

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What must happen to keep everything sterilised?

suitable clothing to avoid bringing in bacteria from outside. Avoiding surfaces to make the microbe without any contamination. Flaming glass bottles get rid of bacteria on the top of the bottle. Sterilising loops to keep bacteria away.

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continued!

sterilising glass spreaders to give bacteria room to grow. Incubate at 25 degrees to allow it to grow. The petri dish must have a lid to stop micro-organisms in the air contaminating the culture. The lid is taped on.

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keeping healthy

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