Response and infection

• Pathogens

  microorganisms that cause infectious diseases
• Communicable diseases


  Infectious so can spread
• Pathogens can be 


  Bacteria,viruses,fungi and protists
• Bacteria pathogens

  -produce rapidly in the body and bacteria can may produce toxins that damage tissues
• viral pathogens

  Viruses infect and reproduce themselves inside body cells and cause damage to body cells
• Human defence system

  nose hair and mucus

  skin is a physical barrier
• White blood cells

  engulf and digest pathogens

  produce antibodies that attach to antigens and antibiotics kill these pathogens
• White blood produce antitxins to counteract toxins
• Vaccination

  -dead pathogen is injected

  -white blood cells stimulate to produce antibodies against pathogens

  memory cells stay in the body

  if reinfected the antibodies are made quickly and in large numbers

  and pathogens is quickly destroyed
• Antibiotics

  cure bacterial disease
• Bacteria becomes resistant to antibiotics

  -antibiotics do not kill viral pathogens

  -as its difficult to develop drugs that kill viruses without damaging body cells
• Painkillers

  treat symptoms of an illness but do not kill parhogen
• First drug

  Penicilline discovered by alexander fleming
• Drugs tested for

  Toxicity and efficacy and dose
• Aspirin comes from

  Willow tree