how to stop pathogens from spreading

• Nose: Nasal hair keeps out dust and larger micro organisms. The production of mucus also helps trap pathogens.
• Skin: The skin is a complete barrier against pathogens (unless cut) and produces antimicrobial secretions.
• Stomach: The stomach produces hydrochloric acid to kill any pathogens that may enter.
• Trachea and Bronchi: Both of these produce mucus to catch pathogens, and are lined with cilia (hairs).
• White blood cells defend the body from pathogens in three different ways:

  1. Phagocytosis;
  2. Producing antibodies;
  3. Producing antitoxins.
• There are two types of white blood cell:

  • Phagocytes
  • Lymphocytes
• Phagocytes ingest pathogens and destroy them by digesting them and can leave the blood via the capillaries to destroy pathogens in tissues.
• • Phagocytosis:
  • Bacteria enters the phagocyte.
  • The phagocyte identifies a pathogen and attaches itself to it.
  • The phagocyte surrounds the bacteria and ingests it.
  • The phagocyte gradually digests the bacteria and is killed.
• Lymphocytes:

  • Produce antitoxins and antibodies
  • Antitoxins neutralise the toxins released by bacteria
  • Antibodies destroy pathogens.
  • Each antitoxin/antibody is specific to one type of toxin/pathogens.
• Antibodies:

  • Cause cell lysis (burst the pathogen).
  • Bind to the pathogen and destroy them directly.
  • Stick the pathogens together which makes it easier for phagocytes to ingest them.
• How antibodies work against pathogens:

  1. Pathogens contain antigens (unique molecules)  on their surface.
  2. When white blood cells detect these antigens, they produce antibodies (proteins) in response.
  3. The antibodies lock onto the antigens, rendering them useless, whilst other white blood cells now destroy them.
  4. Antibodies now know a particular pathogen and can be produced very quickly if the pathogen re-enters the body.
• Antitoxins:

  • Bacteria can produce toxins that are harmful to the human body.
  • White blood cells detect the toxins and produce antitoxins.
  • The antitoxins neutralise the effect of toxins.