non-specific immune response

• antigen - a protein molecule that triggers an immune response
• each antigen has its own unique shape
• antigens are genetically controlled -> mutations in base sequence can affect antigen functionality
• antigens enable the immune system to identify:

  1. pathogens
  2. viral infected cells
  3. cells from other organisms of the same species (transplants)
  4. cancer/tumour cells
  5. toxins released by pathogens
• phagocytosis is a non-specific defence mechanism
• 2 types of phagocytes:

  1. neutrophils
  2. macrophage
• phagocytosis - cellular process of engulfing solid particles, carried out by phagocytes, using the cell membrane
• neutrophils - engulf and digest pathogens
• macrophage - punches holes in the bacteria or sticks proteins together
• phagocytosis process:

  1. pathogen releases chemicals which causes phagocytes to be attracted towards the pathogen, due to the concentration gradient
  2. foreign antigens are recognised on the pathogen's surface
  3. pathogen attaches to the phagocyte by specific protein receptors
  4. pathogen is engulfed into a vesicle forming a phagosome
  5. a lysosome fuses to the phagosome, releasing hydrolytic enzymes to digest the pathogen
  6. soluble, harmless products are excreted out the cell by exocytosis or used by the phagocyte