Our body reacts quickly against microorganisms when recognized by our immune system
Immune system cells are extremely organized, each having its specific function. If the organism comes into contact with any infectious agent, it will develop special lymphocytes , which are called memory cells , capable of recognizing that infectious agent. These cells remain in our body for the rest of our lives, even without having any contact with this infectious agent.
If we have contact with an infectious agent and if it is recognized by memory cells, lymphocytes must reproduce, with the aim of defeating the infectious agents. These agents, therefore, will be discarded from the organism without causing harm.