So the air passageways of our body essentially are line with this mucus membrane. And when we breathe in air and we breathe in these different types of pathogens, these pathogens ultimately are trapped inside that mucus. Now, inside the air pathogeways we also have these hair like projections we call cilia. And the cilia are continually moving in a wavelike fashion. And what the cilia ultimately do is they move these pathogens which are trapped inside the mucus all the way up to our pharynx. And from the pharynx we can actually spit out the mucus along with the pathogens or we can swallow it and the mucus and the pathogens will ultimately end up in our stomach.