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Mucous membrane
Histological section taken from the pyloric antrum, showing the gastric mucosa
Details
Identifiers
Latin	tunica mucosa
MeSH	D009092
TA98	A05.4.01.015 A05.3.01.029 A05.5.01.029 A05.6.01.009 A05.6.01.010 A05.7.01.006 A05.7.01.007 A05.8.02.009 A06.1.02.017 A06.2.09.019 A06.3.01.010 A06.4.02.029 A08.1.05.011 A08.2.01.007 A08.3.01.023 A09.1.02.013 A09.1.04.011 A09.2.03.012 A09.3.05.010 A09.3.06.004 A09.4.02.015 A09.4.02.020 A09.4.02.029 A15.3.02.083
Anatomical terms of microanatomy [edit on Wikidata]

A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue known as the lamina propria. It is mostly of endodermal origin and is continuous with the skin at body openings such as the eyes, eyelids, ears, inside the nose, inside the mouth, lips, the genital areas, 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.

Amphibians, fish, snails, slugs, and some other invertebrates also produce external mucus from their epidermis as protection against pathogens, to help in movement, and to line fish gills. Plants produce a similar substance called mucilage that is also produced by some microorganisms.^[1][2]

Structure

The mucosa is composed of one or more layers of epithelial cells that secrete mucus, and an underlying lamina propria of loose connective tissue.^[3] The type of cells and type of mucus secreted vary from organ to organ and each can differ along a given tract.^[4][5]

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.^[6]: 1 Along with providing a physical barrier, they also contain key parts of the immune system and serve as the interface between the body proper and the microbiome.^[4]: 437

Function

One of its functions is to keep the tissue moist (for example in the respiratory tract, including the mouth and nose).^[4]: 480 It also plays a role in absorbing and transforming nutrients.^{[4]: 5, 813} Mucous membranes also protect the body from itself. For instance, mucosa in the stomach protects it from stomach acid,^{[4]: 384, 797} and mucosa lining the bladder protects the underlying tissue from urine.^[10] In the uterus, the mucous membrane is called the endometrium, and it swells each month and is then eliminated during menstruation.^[4]: 1019

See also

References