Disease

• what are pathogens?

  microorganisms that cause infectious diseases
• what is the structure of a virus?

  DNA with a coat of proteins and lipids
• virus life cycle

  1. enters through the cell membrane
  2. cell produces more components
  3. new viruses are assembled inside the cell
  4. new viruses burst out the cell
• what are bacteria

  prokaryotic organisms that can act as pathogens
• what is the structure of bacteria

  cytoplasm, dna/plasmid, cell membrane and cell wall
• what are fungal and protist diseases?

  eukaryotic organisms that can act as pathogens
• structure and effect of fungi

  cell walls, no chloroplasts, produce toxins
• structure of protists

  do not form tissues, unicellular organisms, parasites
• what is it called when an organism carries a pathogen of protists

  vector
• chemical defences in the body

  lysozyme enzyme in tears, saliva and mucus - digests cell walls

  hydrochloric acid in the stomach - kills pathogens
• physical defences in the body

  skin forms a protective barrier

  mucus in the respiratory system traps pathogens, cilia move these out of the lungs
• 3 ways white blood cells fight pathogens

  phagocytosis - engulf and destroy pathogens

  antibody production- bind to antigens on pathogens and destroy

  antitoxin production - bind to toxins and make them inactive
• what is the purpose of vaccination

  to prevent illness and reduce the spread of pathogens
• how does a vaccine work?

  a small amount of dead/inactive pathogen is injected

  this causes antibodies to be produced

  if the pathogen infects the person in the future, their immune system remembers how to destroy it
• benefits of vaccination

  people become immune without being infected

  spread of pathogens is reduced (herd immunity)
• risks of vaccination

  side effects or mild symptoms of the disease

  only partial protection, different strains of pathogen
• painkiller definition

  medicines that treat symptoms of a disease but do not kill pathogens
• what do antibiotics do

  kills bacteria inside the body

  slow down or stop the growth of bacteria
• why is it hard to treat viruses

  they reproduce inside body cells so its hard to kill the virus without killing the cell
• why are new drugs tested

  to determine their toxicity, efficacy and dose
• two types of drug testing

  preclinical - tested on cells and tissues, then live animals

  clinical - low doses given to healthy people, then given to patients to test efficacy and dose