Andrew Huberman· PhD
it basically consists of three major lines of Defense there's a physical barrier or rather a set of physical barriers that exist between the organs of your body and the outside world and you're probably immediately thinking skin and yes indeed it includes your skin but also some interesting things like the mucosal lining of your nose and mouth and even some of the liquids that are on the surface of your eyes we'll talk about those in a moment then there's a second line of defense which is for any virus or bacteria or fungus for that matter but today we're talking about viruses colds and flu viruses any viruses that get past the physical barrier of your skin and the mucosal lining of particular regions of your body well then you have What's called the innate immune system