eli5 why you don’t get infections from your mouth, nose, or ears often? What’s the difference between those openings and if you had an open wound which could easily get infected

Question

eli5 why you don’t get infections from your mouth, nose, or ears often? What’s the difference between those openings and if you had an open wound which could easily get infected

In: 37

Answer 1

These openings have defense mechanisms in the form of mucous membranes, waxes, acids, enzymes, and/or hairs.

Also, it’s important to note that they are *not* direct openings to the “inside” of your body. The inside of your mouth, nose, ears, etc. are all covered with the same class of tissue that covers the outside of your body (epithelium). Biologically speaking, nothing is actually *inside* your body until it crosses a membrane, so something that is in your mouth, for instance, is not inside of your body. You could swallow a penny and have it travel all the way through and out the other end, and it will never have actually entered your body from a biological standpoint.