human defences

• skin (4 points)

  1. first line of defence
  2. bacteria lives on the skin as it cant get through
  3. top layer sheds many times and gets rid of the bacteria on it
  4. sebaceous glands produce antimicrobial oil
• nose hairs (3 things)

  1. first line of defence
  2. when you breathe air, you breathe in all solids contained in the air
  3. traps the solids in mucus which can be removed by blowing or swallowing
• trachea and bronchi (4 points)

  1. contains cilia
  2. goblet cells produce mucus which traps pathogens
  3. cilia wafts the mucus containing microorganisms to the back of the throat
  4. it is then swallowed and the stomach acid destroys it
• stomach acid (4 points)

  1. contains HCl
  2. pH of 2 and is very corrosive
  3. coated with lining to stop the walls for the corroding
  4. any microorganisms trapped in mucus go here and the acid destroys the cell walls and kills them
• tears and eyelashes (4 points)

  1. acts as a barrier when eyes are open and traps dirt to prevent infection
  2. high salt content which drys up microorganisms
  3. washes out microorganisms and breaks down bacterial cell walls
  4. lysozyme- enzyme in tears, mucus, blood, saliva
• scabs

  1. fibrin stretches across the wound which pulls the edges closer and forms a mesh
  2. additional platelets and red blood cells get caught in the mesh and forms a clot that dries into a scab