Fighting disease

• reducing spread of diseases

  • being hygienic
  • destroying vectors
  • isolating infected individuals
  • vaccination
• stomach produces hydrochloric acid to kill pathogens
• skin has an outer layer that prevents entry into body
• hair and mucus in your nose traps particles which could contain pathogens
• your immune system can attack pathogens white blood cells can destroy pathogens
• white blood cells can engulf foreign cells and digest them this is called phagocytosis
• antigen


  proteins found on the surface of pathogens
• when white blood cells come across a foreign antigen, they produce antibodies to destroy it. antibodies produced are specific to that type of antigen
• a pathogen is recognised as foreign because of its antigens
• anti toxins


  counteract the toxins produced by bacteria
• when you're infected with a new pathogen it takes your white blood cells a few days to learn how to deal with it - by that time you can be pretty ill
• vaccinations can protect from future infections
• vaccinations usually involve injecting small amounts of dead pathogens - these carry antigens which cause your body to produce antibodies to attack them. if pathogens of the same type ever appear again the white blood cells can rapidly produce antibodies to kill off the pathogen
• Vaccination

  • help control lots of communicable diseases
  • big outbreaks of disease are prevented
  • vaccinations don't always work
  • can have a bad reaction to it
• drugs

  • painkillers - relieve pain
  • antibiotic - kill bacteria
• bacteria can become resistant to antibiotics
• bacteria can mutate - sometimes the mutations cause them to be resistant to an antibiotic
• plants produce a variety of chemicals to defend themselves against pathogens some of these chemicals can used as drugs to treat human diseases
• drugs from plants

  • aspirin - a painkiller to lower fever - developed from a chemical found in willow
  • digitalis - treats heart conditions - developed from a chemical found in foxgloves
• drugs extracted from microorganisms - penecilin

  • Alexander fleming noticed that a petri dish containing bacteria also had mould on it and the area around the mould was free of the bacteria - he found the the mould produced a substance that killed bacteria - this is called penicillin
• Lymphocytes are white blood cells produced by bone marrow that produce antibodies
• how does the human body prevent pathogens from entering

  • skin - physical barrier
  • stomach - contains HCL to kill bacteria
  • eyes - tears contain enzymes to kill bacteria
  • breathing system trachea, bronchi & nose produce mucus to trap bacteria
• how does the human body defend itself against pathogens inside the body?

  • white blood cells engulf pathogens and digest them
  • antibodies are produced - help destroy pathogens. memory cells are formed and they give a more rapid response if pathogen returns
  • antitoxins are produced which neutralise toxins