Diseases and Immunity

• WHAT IS A PATHOGEN

  aa microorganism that causes diseases
• WHAT IS A TRANSMISSIBLE DISEASE?

  a diseases that can be transferred between hosts
• 5 WAYS DISEASES CAN BE SPREAD

  Droplets in air

  contaminated food

  contaminated water

  direct contact

  entry through wounds
• 2 CHEMICAL DEFENCES

  • stomach acid : kills pathogens
  • mucus : traps bacteria and prevents them from entering the body
• 2 MECHANICAL BARRIERS

  • skin : acts as barrier
  • nose hairs : trap and waft dirt away from the airway
• 2 WAYS WHITE BLOOD CELLS PROTECT THE BODY

  phagocytosis --> phagocytes

  produces antibodies --> lymphocytes
• HOW DO ANTI BODIES WORK?

  1. specific antibodies bind to antigen on the pathogen
  2. antibodies destroy pathogen or make it easier for phagocytes to carry out phagocytosis
• WHY CAN CERTAIN ANTIGENS ONLY BIND TO CERTAIN PATHOGENS?

  each antibody has a specific shape and can only bind to specific and complementary antigens on pathogens
• WHAT IS ACTIVE IMMUNITY ?

  type of immunity where WBCs produce antibodies against a pathogen
• 2 METHODS OF ACTIVE IMMUNITY

  • vaccination
  • infection with pathogen
• HOW DO VACCINES WORK?

  dead, weak, inactive pathogens are injected into the body

  the lymphocytes produce antibodies for that pathogen

  proteins known as memory cells are produced so that if the pathogens infect that person again, antibodies can be produced faster
• METHODS TO CONTROL SPREAD OF DISEASE?

  • hygienic food preparation
  • good personal hygiene
  • proper waste disposal
  • sewage control to ensure it doesn't contaminate drinking water
• HERD IMMUNITY 


  vast majority of population in vaccinated which prevents the disease from spreading as fewer number of people remain unvaccinated for disease to spread between
• WHAT IS PASSIVE IMMUNITY

  a type of immunity where antibodies are transferred from one individual to another

  ex. mother to infant
• WHY IS PASSIVE IMMUNITY SHORT TERM?

  no memory cells are produced
• WHY IS PASSIVE IMMUNITY IMPORTANT TO INFANTS?

  infants have not yet had time to develop their own antibodies as they have not been exposed to many pathogens
• WHAT IS AUTOIMMUNE DISEASE?

  Immune system attacks body cells
• EXAMPLE OF AUTO IMMUNE DISEASE

  type 1 diabetes
• WHAT HAPPENS AFTER THE ANTIBODY BINDS WITH ANTIGEN?

  antibodies will cause agglutination which is clumping of pathogens

  So that pathogens cannot move easily

  Chemicals are released, these signal phagocytes to enhance activity of phagocytosis