American Academy of Professional Coders (AAPC) 2026 – 400 Free Practice Questions to Pass the Exam

The mucous membrane is specifically designed to help maintain a moist environment in various cavities of the body that are open to the exterior. This type of membrane produces mucus, which serves to lubricate and protect the surfaces it covers, such as those in the digestive, respiratory, and urogenital tracts. The mucus secreted by these membranes not only keeps the tissues moist but also serves important functions in trapping pathogens and particles, facilitating absorption and secretion.

In contrast, serous membranes line closed body cavities and produce serous fluid to reduce friction between organs, while synovial membranes line joint cavities and secrete synovial fluid to lubricate joint surfaces. Meninges are protective membranes surrounding the brain and spinal cord, but they do not create a moist environment in the same way that mucous membranes do.