+A **mucosa**, or mucous membrane, is a moist [Lining](/wiki/lining) that protects many internal surfaces of the body. It often secretes [Mucus](/wiki/mucus) to keep these surfaces lubricated and hydrated. This vital layer forms a barrier against external threats.
+## See also
+- [Epithelium](/wiki/epithelium)
+- [Tissue](/wiki/tissue)
+- [Gland](/wiki/gland)