What type of barrier do mucous membranes provide?

Mucous membranes primarily provide a physical barrier against pathogens and foreign substances. They line various body cavities and internal organs, acting as a protective layer that traps and expels microbes, dust, and other particles. The physical structure of mucous membranes helps to prevent the entry of pathogens by providing a thick, moist surface that can hinder their attachment and proliferation.

Additionally, mucous membranes are often associated with certain biological components, such as mucus, which contains antimicrobial substances. However, the defining feature of their barrier function is the physical aspect, making them an essential part of the innate immune system.

In summary, while mucous membranes can also have chemical and biological properties contributing to their protective role, it is their physical characteristics that primarily establish them as a barrier against infection and external harm.