# Mucous Membranes **Mucous membranes** are a type of [[tissue]] that line [[body cavity|body cavities]] and hollow areas that are open to the "outside" of the body. They help protect underlying tissues, secrete helpful substances, and help absorb nutrients. The structure....is...something.... lamina propria ... but is this only in the mucous membrane or elsewhere? Mucous membranes are found lining various parts of our bodies. Three examples of which are: - the [[respiratory tracts]] - the [[digestive system|gastrointestinal tract]] - the [[urinary system|genitourinary tract]] **Mucus** is a substance that we produce that acts as protection and lubrication (and probably other stuff too), which is made when a secretion called **mucin** mixes with water. [[goblet cell|goblet cells]] (and other things too?) secrete mucin. (Note: **mucous** is the adjective used to describe stuff having to do with...mucus.) ## Mucous Membranes in the Immune System Mucous membranes are an important part of the [[innate immune system#First Line Defense|first line defense]] of the innate immune system. Besides providing a physical barrier, the mucous membrans can also physically move microbes to the outside of the body so they can be expelled. For example, the "cillary escalator" in the lungs, which begins with the [[cilia]] in the [[goblet cell|goblet cells]] in the lungs move back and forth and ___