Despite being surrounded by harmful microorganisms, toxins, and the threat of our own cells turning into tumor cells, humans manage to survive; largely thanks to our immune system.
The immune system is made up of organs, tissues, cells, and molecules that all work together to generate an immune response that protects us from microorganisms, removes toxins, and destroys tumor cells - hopefully not all at once!
The immune response can identify a threat, mount an attack, eliminate a pathogen, and develop mechanisms to remember the offender in case you encounter it again - all within 10 days.
In some cases, like if the pathogen is particularly stubborn or if the immune system starts attacking something it shouldn't be like your own tissue, it can last much longer, for months to years, and that leads to chronic inflammation.
Your immune system is like the military - with two main branches, the innate immune response and the adaptive immune response.
The innate immune response includes cells that are non-specific, meaning that although they distinguish an invader from a human cell, they don't distinguish one invader from another invader.
The innate response is also feverishly fast - working within minutes to hours.
Get it? "Feverishly" - that's cause it's responsible for causing fevers.
The trade off for that speed is that there's no memory associated with innate responses.
In other words, the innate response will respond to the same pathogen in the exact same way no matter how many times it sees the pathogen.
