if a pathogen gets past primary defences and enters the body the immune system will respond
antigens are molecules found on the surface of cells. when a pathogen invades the body the antigens on its cell surface are recognised as foreign which activates the immuneresponse
non specific response
happens the same way in all organisms whatever foreign antigens they have
specific response
antigen-specific, aimed at specific pathogens, involves white blood cells ( T and B lymphocytes )
