Mucous membranes

The mucous membranes (or mucosae; singular: mucosa) are linings of mostly endodermal origin, covered in epithelium, and are involved in absorption and secretion. They line various body cavities that are exposed to the external environment and internal organs. It is at several places continuous with skin: at the nostrils, the lips, the ears, the genital area, and the anus. The sticky, thick fluid secreted by the mucous membranes and gland is termed mucus. The term mucous membrane refers to where they are found in the body and not every mucous membrane secretes mucus.
See more at Wikipedia.org...

Mucous membranes The inner tissue that covers or lines body cavities or canals open to the outside, such as nose and mouth. [more]Mucous membranes - Community and Resources