<Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> A mucous membrane or mucosa is a membrane that lines various cavities in the body and surrounds internal organs . It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue . It is mostly of endodermal origin and is continuous with the skin at various body openings such as the eyes, ears, inside the nose, inside the mouth, lip, the urethral opening and the anus . Some mucous membranes secrete mucus, a thick protective fluid . The function of the membrane is to stop pathogens and dirt from entering the body and to prevent bodily tissues from becoming dehydrated . </P> <P> The mucosa of organs are composed of one or more layers of epithelial cells that secrete mucus, and an underlying lamina propria of loose connective tissue . The type of cells and type of mucus secreted vary from organ to organ and each can differ along a given tract . </P> <P> Mucous membranes line the digestive, respiratory, and reproductive tracts and are the primary barrier between the external world and the interior of the body; in an adult human the total surface area of the mucosa is about 400 square meters while the surface area of the skin is about 2 square meters . They are at several places contiguous with skin: at the nostrils, the lips of the mouth, the eyelids, the ears, the trachea, the stomach, the genital area, and the anus . Along with providing a physical barrier, they also contain key parts of the immune system and serves as the interface between the body proper and the microbiome . </P>

Protects to the external surfaces of the body from infection