communicable disease, prevention and immune system

• primary response:

  • pathogen enters for the fist time
  • not mant B lymphocytes that can make the correct antibody
  • show symptoms
  • memory cells produced
  • t lymphocytes record antigen on pathogen
  • b lymphocytes remember specific antibodies

  
• secondary response:

  • same pathogen enters body
  • clonal selection is faster
  • memory b lymphocytes divide into plasma cells (that produce the correct antibody)
  • memory t lymphocytes divide and kill the pathogens with the antigen
  • may not show symptoms

  
• antigen: a protein on the surface of a pathogen that initiates an immune response by causing antibody production
• antibody: made by b lymphocyte in response to antigen - released into bloodstream
• antibody

  
• constant region: same in all antibodies - has a site where it binds to immune system cell
• variable region: different on different anti-bodies, complementary to antigens
• 2 antigen binding sites can bind to more than one pathogen
• light polypeptide chains are present but heavy polypeptides contain the site at which the antibody can bind to a cell
• name the three types of antibodies:

  1. opsonins
  2. agglutinins
  3. anti-toxin
• opsonins:

  • antibodies that bind to antigens
  • act as markers for phagocytes
  • act as site for phagocytes to bind and then engulf pathogens
• agglutinins: bind to antigens and cause clumping (preventing them from entering body cells)
• anti-toxin:

  • bind to toxins to prevent harm to human cells
  • phagocytes then engulf the 'toxin-antibody' complex
• active immunity:

  • can be natural or artificial
  • exposure to antigen
  • takes time for protection to develop
  • memory cells
• passive immunity:

  • can be natural or artificial
  • no exposure to antigen
  • protection is immediate
  • short-term protection
  • no memory cells produced
• example of natural active immunity is getting infected with a pathogen and immune system actively trying to destroy the pathogen in the body
• example of artificial active immunity: a vaccination with weakened/dead form of the pathogen
• example of natural passive: antibodies being passed from the mother to the baby whilst breastfeeding
• example of artificial passive immunity: vaccination with only antibody
• herds immunity: when unvaccinated people are protected because of the occurrence of the disease is reduced by the number of people who are vaccinated
• 4 shapes of bacteria:

  1. cocci (spherical)
  2. bacilli
  3. spirrilli
  4. vibrio
• Vibrio in wet environment
• Spirrilli in wet environment
• Bacilli in wet environment
• Cocci in dry environment
• Problems with bacteria reproducing quickly: spread of disease and food spoilage
• Bacteria caused disease by:

  • produce toxin and cause symptoms by cell damage
  • damage cell membrane, enzymes or genetic material
• Virus - bacteriophage (add annotated diagram
• how bacteriophages invade living cells:

  1. attach to specific host cell
  2. genetic material from the virus is injected into host cell
  3. the viral genes cause the host cell to make new virus cells
  4. host cell splits open
• Retrovirus replication:

  transcription - Viral RNA synthesised by host cell

  reverse transcription - reverse transcriptase enzyme creates DNA from the virus RNA

  integration - virus genetic information now within host DNA
• fungi reproduce by budding which is asexual reproduction
• protoctists are unicellular and have a nucleus
• three types of direct transmission:

  1. direct contact
  2. inoculation
  3. ingestion
• direct contact: contact with bodily fluids, skin to skin or microbes from faeces
• inoculation: through break in skin, animal bite, punctured wound or sharing needles
• ingestion: taking in contaminated food/drink - transferring pathogens from hand to mouth
• three types of indirect transmission:

  1. fomites
  2. droplets
  3. vectors
• fomites: inanimate objects (bedding, socks, cosmetics)
• three types of non-specific defense mechanisms:

  1. inflammation
  2. fever
  3. phagocytes
• how does inflammation help prevent pathogens reproducing?

  mast cells in damaged tissues release cytokines and histamines