| Serous membrane | |
|---|---|
 Stomach. (Serosa is labeled at far right, and is colored yellow.) | |
| Details | |
| Precursor | Mesoderm |
| Identifiers | |
| Latin | tunica serosa |
| MeSH | D012704 |
| FMA | 9581 |
| Anatomical terminology | |
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| This article is one of a series on the |
| Gastrointestinal wall |
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Theserous membrane (orserosa) is a smoothepithelial membrane ofmesothelium lining the contents and inner walls ofbody cavities, which secreteserous fluid to allowlubricatedsliding movements between opposing surfaces. The serous membrane that coversinternal organs (viscera) is calledvisceral, while the one that covers the cavity wall is calledparietal. For instance theparietal peritoneum is attached to theabdominal wall and thepelvic walls.[2] Thevisceral peritoneum is wrapped around the visceral organs. For the heart, the layers of the serous membrane are called parietal and visceralpericardium. For the lungs they are called parietal and visceral pleura. The visceral serosa of theuterus is called theperimetrium. Thepotential space between two opposing serosal surfaces is mostly empty except for the small amount of serous fluid.[3]
The Latin anatomical name istunica serosa. Serous membranes line and enclose severalbody cavities, also known as serous cavities, where they secrete a lubricating fluid which reduces friction from movements. Serosa is entirely different from theadventitia, aconnective tissue layer which binds together structures rather than reducing friction between them. The serous membrane covering theheart and lining themediastinum is referred to as thepericardium, the serous membrane lining thethoracic cavity and surrounding thelungs is referred to as thepleura, and that lining theabdominopelvic cavity and theviscera is referred to as theperitoneum.
Serous membranes have two layers. The parietal layers of the membranes line the walls of the body cavity (pariet- refers to a cavity wall). The visceral layer of the membrane covers the organs (the viscera). Between the parietal and visceral layers is a very thin, fluid-filled serous space, or cavity.[4]
Each serous membrane is composed of a secretoryepithelial layer and aconnective tissue layer underneath.
For the heart, the layers of the serous membrane are called the parietalpericardium, and the visceral pericardium (sometimes called theepicardium). Other parts of the body may also have specific names for these structures. For example, the serosa of theuterus is called theperimetrium.
Thepericardial cavity (surrounding theheart), pleural cavity (surrounding thelungs) andperitoneal cavity (surrounding most organs of theabdomen) are the three serous cavities within the human body. While serous membranes have a lubricative role to play in all three cavities, in the pleural cavity it has a greater role to play in the function of breathing.
The serous cavities are formed from the intraembryonic coelom and are basically an empty space within the body surrounded by serous membrane. Early in embryonic life visceral organs develop adjacent to a cavity and invaginate into the bag-like coelom. Therefore, each organ becomes surrounded by serous membrane - theydo not lie within the serous cavity. The layer in contact with the organ is known as the visceral layer, while the parietal layer is in contact with the body wall.
In the human body, there are three serous cavities with associated serous membranes:
The two layers of serous membranes are namedparietal andvisceral. Between the two layers is a thin fluid filled space.[4] The fluid is produced by the serous membranes and stays between the two layers to reduce friction between the walls of the cavities and the internal organs when they move with respect to one another, such as when the lungs inflate or the heart beats. Such movement could otherwise lead to inflammation of the organs.[4]
All serous membranes found in the human body are formed ultimately from themesoderm of thetrilaminar embryo. The trilaminar embryo consists of three relatively flat layers ofectoderm,endoderm, andmesoderm.
As the embryo develops, the mesoderm starts to segment into three main regions: theparaxial mesoderm, theintermediate mesoderm and thelateral plate mesoderm.
The lateral plate mesoderm later splits in half to form two layers bounding a cavity known as theintraembryonic coelom. Individually, each layer is known assplanchnopleure andsomatopleure.
Theintraembryonic coelom can now be seen as a cavity within the body which is covered with serous membrane derived from the splanchnopleure. This cavity is divided and demarcated by the folding and development of the embryo, ultimately forming the serous cavities which house many different organs within thethorax andabdomen.
Mesotheliomas areneoplasms that are relatively specific for serous membranes. The modifiedMüllerian-derived serous membranes that surrounds theovaries in females can give rise toserous tumors, a solid to papillary tumor type that may also arise within theuterus.
This Wikipedia entry incorporates text from the freely licensed Connexions[1] edition of Anatomy & Physiology[2] text-book by OpenStax College
{{cite book}}: CS1 maint: location missing publisher (link)