Fighting Disease

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  • Created by: Abc312
  • Created on: 10-05-18 19:51
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  • Fighting Disease
    • Physical Human Defence Systems
      • Skin
        • A barrier to pathogens.
        • Secretes antimicrobial substances
      • Nose
        • Hairs and mucus in the nose trap particles that could contain pathogens
      • Trachea and Bronchi
        • Secrete mucus to trap pathogens
        • Lined with cilia which are like hairs.
          • They waft the mucus up to the back of the throat where it can be swallowed.
      • Stomach
        • Produces hydrochloric acid to kill pathogens.
    • White blood Cells
      • They are the most important part of the immune system in the defence of disease
      • Phagocytocisis
        • They engulf foreign pathogens and digest them
      • Antitoxin production
        • These counteract toxins produced by the invading bacteria
      • Producing antibodies
        • Every pathogen has unique antigens on its surface.
        • When a white blood cell comes across a foreign antige it starts to produce proteins called antibodies
          • They lock onto the invading cells so they can be found and destroyed
          • Each antibody is unique to that type of antigen so it won't lock onto any other.
        • Antibodies produce rapidly and are carried around the body to find all similar bacteria or viruses
        • If the person is infected with the same pathogen the white blood cells recognise it so the antibodies are produced rapidly so they won't get ill.
    • Vaccinations
      • Vaccinations involve injecting the person with small amounts of dead or inactive pathogens.
        • This causes your body to produce antigens to that pathogen.
          • This means that if you get it again your body can fight it quickly.
      • They can help control epidemics
        • Because even those who are not vaccinated are unlikely to catch it because there are fewer people that are able to catch it and therefore spread it on.
        • If a lot of people aren't vaccinated then the disease can spread quickly.
    • Drugs
      • Antibiotics
        • Eg. penicillin
        • Cure bacterial diseases
          • Kill/ prevent growth of the bacteria
        • Specific antibiotics need to be used for specificbacteris
        • Don't destroy viruses
          • Because they reproduce using body cells.
            • It is very hard to find a drug that kills the virus without killing the cell.
        • Antibiotics have greatly reduced deaths from infectious bacterial diseases
        • Overuse of antibiotics can lead to certain strains of bacteria mutating and becoming resistant
          • This means that that certain strain of bacteria will not be killed be the bacteria
          • The chance of this happening can be reduced by
            • Not overprescribingantibiotics
            • Finishing  the whole course of antibiotics
          • MRSA  causes wound infections resistant to the powerful antibiotic methicillin
      • Painkillers
        • Relieve the symptoms of diseases
        • Don't kill the pathogen
      • Drug discovery and development
        • Traditionally drugs came from plants and microorganisms.
          • Penicillin comes from the Penicillium mould
          • The painkiller aspirin comes a chemical found in willow.
          • The heart drug digitalis originates from a chemical found in foxgloves.
        • Most new drugs are synthesised by chemists in the pharmaceutical industry
        • Testing drugs
          • Preclinical-laboratory
            • Uses human cells and tissues
            • However this doesn't test the affects of whole/multiplebody systems
            • They are then tested on animals
              • This tests if it works, how harmful it is (toxicity) and the best dosage.
              • It is law that a new drug must be tested on two live animals.
              • People believe that this is cruel but it is the safest way.
          • Clinical-on people
            • First is tested on healthy volunteers
              • This checks for harmful side affects.
              • This is usually done by starting with a very small dose and gently increasing it.
            • If it is ok with healthy volunteers it is tested on people with the illness
              • The optimum dose is found- where it is most effective with the least side effects.
            • To test how well it works a double blind trial is usually carried out.
              • Some patients are given the drug and others are given a placebo.
                • This allows for the placebo affect- where you excpect it to work so you feel better.
              • Neither the doctor or patient knows if they have a placebo.
          • New drugs have to be tested before used to check that they are safe.
          • They are tested for toxicity,efficinecy and dose amount.

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