Changes

: The [[nose]] has [[hair]]s which act as a physical barrier as they can trap [[microorganismmicro-organism]]s before they enter the [[lung]]s.: The [[nose]] is full of [[mucus]] which acts as a physical barrier since it is a sticky substance which [[microorganismmicro-organism]]s can get stuck in. This [[mucus]] is then swallowed into the harsh environment of the [[stomach]] which kills [[microorganismmicro-organism]]s.

: The [[trachea]] is full of [[mucus]] which acts as a physical barrier since it is a sticky substance which [[microorganismmicro-organism]]s can get stuck in. This [[mucus]] is then swept up away from the [[lung]]s by [[Ciliated Epithelial Cell]]s into the throat where it is then swallowed into the harsh environment of the [[stomach]] which kills [[microorganismmicro-organism]]s.