B6 Preventing disease

• How does skin stop pathogens?

  Physical barrier, produces antimicrobial secretions, micro-organisms on the skin stop pathogens
• how does the nose stop pathogens?

  cilia and mucus trap particles in the air, preventing them from entering the lungs
• how do the trachea and bronchi stop pathogens?

  trachea produces mucus which is moved away from the lungs to the back of the throat by cilia where it is expelled, taking the pathogens it trapped with it.
• how does the stomach stop pathogens?

  produces strong acid (pH2) that destroys pathogens
• what non-specific systems does the body use to stop pathogens getting into it?

  skin, cilia and mucus in the nose, stomach acid
• three functions of white blood cells?

  phagocytosis; produce antibodies; produce anti-toxins
• what is phagocytosis?

  phagocyte attracted to area of infection; engulfs pathogen; releases enzymes to digest pathogen
• what are two types of white blood cell?

  lymphocytes and phagocytes
• how do lymphocytes fight pathogens?

  produces anti-toxins that neutralise toxins produced by pathogens; produces antibodies that target and bind to antigens on the pathogen surface
• what are antigens?

  proteins on the surface of a pathogen
• what does a vaccine contain?

  small quantites of a dead or inactive form of a pathogen
• what is herd immunity?

  when most of a population is vaccinated again disease making it less likely to spread
• what is an antibiotic?

  a drug that kills bacteria BUT NOT viruses
• what is a placebo?

  medicine with no active ingredient given to patients instead of the real drug in a drug trial
• what is a double blind trial?

  a test where neither patient nor doctor know who receives the real drug and who gets the placebo
• how can you avoid getting malaria?

  use insect repellent; take anti malarial tablets; use bed nets to stop mosquitos; wear long sleeved clothing
• how is HIV prevented?

  sexually transmitted so use condoms