B3 - Infection and Response

• Pathogen


  A disease-causing microorganism
• Vector


  An organism that carries a pathogen but does not suffer from the disease
• Toxin


  A poisonous chemical, produced by certain pathogens
• Non-specific defences


  • The first line of defence against pathogens in general; includes skin, hair, mucus, etc.
• Immune system


  • The body's defence system against infections and diseases (consists of white blood cells and antibodies)
• Phagocytosis


  The process by which a white blood cell, engulfs and digests a pathogen
• Antibody


  A protein produced by the immune system to kill specific pathogens
• Antigen


  A protein with a specific shape found on the surface of microorganisms
• Antitoxin


  A chemical released from white blood cells that can neutralise toxins
• Immunity


  The ability to attack a pathogen before it causes disease due to a previous encounter with the pathogen
• Vaccination

  A dead or weakened form of a pathogen, injected into the body so that it can learn to produce the correct antibodies for the pathogen's antigens. When the patient catches the disease, their body can fight it more efficiently because it recognises the antigens
• Antibiotics


  Medication used to kill bacterial pathogens inside the body
• MRSA


  An antibiotic-resistant bacterium; a 'superbug'
• Digitalis


  A drug extracted from foxgloves, used to treat heart problems
• Aspirin


  A painkilling drug first extracted from the bark of willow trees
• Penicillin


  An antibiotic extracted from the Penicillium fungus
• Double-blind trial


  A trial where neither the patient nor the doctor know if the patient is receiving the test drug or a placebo
• Placebo


  A dummy drug given to patients during drug trials
• Measles:

  •Caused by a virus

  •Spread by humans coughing

  •Symptoms are skin rash and fever

  •Treated by preventing it with a vaccine
• HIV:

  • Caused by a virus

  • Spread by sexual contact or needle sharing

  • Flu-like symptoms, weakened immune system

  • No treatment, drugs can stop it becoming AIDS
• HIV:

  • Caused by a virus

  • Spread by sexual contact or needle sharing

  • Flu-like symptoms, weakened immune system

  • No treatment, drugs can stop it becoming AIDS
• Tobacco Mosaic Virus:

  • Caused by a virus

  • Spread by contact with infected plants

  • Causes mottling and discolouration of leaves

  • Treated by culling infected plants
• Rose Black Spot:

  • Caused by a fungus

  • Spread by spores in water or wind

  • Causes black spots to develop on leaves

  • Treated by fungicides and culling infected plants
• Malaria:

  • Caused by a protist

  • Spread by vectors (mosquitos)

  • Causes fever and death

  • Treated by prevention with vaccinations and killing vectors
• Salmonella:

  • Caused by bacteria

  • Spread by eating contaminated food

  • Causes fever and vomiting

  • No treatment except time and painkillers for symptoms
• Gonorrhoea:

  • Caused by bacteria

  • Spread by sexual contact

  • Causes painful urination and yellow discharge

  • Treated with antibiotics, and avoiding catching it
• Pathogens:

  • Bacteria

  • Viruses

  • Protists

  • Fungi
• Drug testing:

  1. Human cells/tissues
  2. Live animals
  3. Human volunteers