BIOLOGY P1

• Vaccine


  Exposes the body to weakened or inactivated pathogens, allowing the immune system to develop immunity without causing the full disease
• Vaccines


  • Contain weakened or inactivated pathogens that the body can respond to and develop immunity against
  • Do not cause the full disease
• Body exposed to pathogen


  Develops immunity to that pathogen and any diseases it causes
• Body develops immunity


  Cannot catch the disease anymore
• How vaccines work


  1. Expose body to weakened pathogens

  2. Body produces antibodies and develops immunity
• Diseases vaccines can work against

  • Bacteria
  • Viruses
• By primary school, we've been vaccinated against more than a dozen diseases that could otherwise kill us
• Pros of vaccines


  • Protect us from horrible diseases
  • Help control and prevent outbreaks of diseases that used to be common
• Herd immunity


  When enough people in a population are immune to a pathogen, the pathogen has no one to spread to and disappears
• Herd immunity


  Even unvaccinated people are unlikely to catch the disease
• Pros of vaccines generally outweigh the cons
• Cons of vaccines


  • Vaccines don't always grant full immunity
  • Can sometimes cause bad reactions like swelling, fevers, or seizures
• Severe vaccine reactions are super rare
• Physical and chemical barriers

  Stop pathogens from getting into the body
• Immune system


  Destroys any pathogens that do make it into the body
• Skin


  • Acts as a physical barrier that pathogens can't get through
  • Secretes oils and antimicrobial substances that can kill pathogens
• Nose


  Has hairs and mucus that can trap pathogens and particles in the air
• Trachea and esophagus


  Only two tubes leaving the throat that pathogens can enter
• Trachea, bronchi, and bronchioles

  1. Covered in mucus that traps particles

  2. Lined with cilia that move mucus and trapped particles up to the throat to be swallowed
• Stomach acid


  Hydrochloric acid that kills most pathogens
• White blood cells


  Patrol the body and have three important functions: phagocytosis, producing antitoxins, and producing antibodies
• Phagocytosis


  Process where white blood cells consume and destroy pathogens
• Antitoxins


  Small molecules produced by white blood cells that can bind and counteract toxins produced by pathogens
• Antigens


  Substances detected by the immune system as foreign, such as the cell wall of a bacteria or a virus protein
• Antibodies


  Small proteins made by white blood cells that can lock onto specific antigens and signal for their destruction
• Immune system remembers pathogens

  Produces many antibodies quickly to destroy pathogens before they can develop
• The body survives millions of pathogens attacking it every day