00:01
All right.
00:01
So in this question, we are addressing the first line of defense.
00:08
Okay, first line of defense, essentially, is anything that stops the pathogen, the bad guy, the one that's going to make us sick, right, stops the pathogen from entering the body.
00:44
Now, these could be like physical barriers, like a good example of that is your skin or linings of digestive tract or respiratory tract.
01:09
Those are actually things that block, physically block pathogens from entering.
01:13
Okay.
01:15
Other things that can block could be chemical.
01:20
Like all sorts of body fluids, chemical, body fluids, like saliva, mucus, urine, digestive fluid, all those things can be a combination chemical, also mechanical, like flushing things out, like urine flow...