Defending against infection
The two types of pathogens are bacteria and viruses which are micro-organisims.
Bacteria can multiply rapidly and release toxins which can make us ill.
Viruses on the other hand are smaller and can get inside a cell where they reproduce hundreds of thousands of copies of themselves, burst the cell and pass out through the bloodstream, airways, or other outlets.
There are two types of white bood cells which prevent bacteria and viruses which are phagocytes and lymphoocytes.
Phagocytes ingest the pathogens, or use enzymes to attack them.
Lymphocytes multiply when confronting a disease, making lots of proteins called antibodies which attack the pathogens.
Vaccination is a method to help fight infection, The idea is to inject an inactive form of…