出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/09/06 20:13:06」(JST)
| Serous Membrane | |
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Stomach. (Serosa is labeled at far right, and is colored yellow.)
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| Latin | tunica serosa |
| Precursor | mesoderm |
| MeSH | Serous+membrane |
| Anatomical terminology | |
| This article is one of a series on the |
| Gastrointestinal wall |
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General structure
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Specific
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Organs
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In anatomy, serous membrane (or serosa) is a smooth membrane consisting of a thin layer of cells which secrete serous fluid, and an underlying thin epithelial layer. The Latin anatomical name is tunica serosa. Serous membranes line and enclose several body cavities, known as serous cavities, where they secrete a lubricating fluid which reduces friction from muscle movement. Serosa is entirely different from the adventitia, a connective tissue layer which binds together structures rather than reducing friction between them. The serous membrane covering the heart and lining the mediastinum is referred to as the pericardium, the serous membrane lining the thoracic cavity and surrounding the lungs is referred to as the pleura, and that lining the abdominopelvic cavity and the viscera is referred to as the peritoneum.
A serous membrane (also referred to as a serosa) is one of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavities. 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.[1]
Each serous membrane is composed of a secretory epithelial layer and a connective tissue layer underneath.
For the heart, the surrounding serous membranes include:
| Outer | Inner |
| Parietal pericardium | Visceral pericardium (epicardium) |
Other parts of the body may also have specific names for these structures. For example, the serosa of the uterus is called the perimetrium.
The pericardial cavity (surrounding the heart), pleural cavity (surrounding the lungs) and peritoneal cavity (surrounding most organs of the abdomen) 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 - they do 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.
There are three serous cavities and their associated membranes. Serous membrane lines the pericardial cavity and reflects back to cover the heart—much the same way that an underinflated balloon would form two layers surrounding a fist. The pericardium is a two-layered sac that surrounds the entire heart except where the blood vessels emerge on the heart’s superior side.[1]
The pleura is the serous membrane that surrounds the lungs in the pleural cavity; the pericardium is the serous membrane that surrounds the heart in the pericardial cavity; and the peritoneum is the serous membrane that surrounds several organs in the abdominopelvic cavity. The serous fluid produced by the serous membranes reduces friction between the walls of the cavities and the internal organs when they move, such as when the lungs inflate or the heart beats, that could otherwise lead to inflammation of the organs.[1]
The serous membranes have two layers; parietal and visceral, surrounding a fluid filled space.[1]
All serous membranes found in the human body formed ultimately from the mesoderm of the trilaminar embryo. The trilaminar embryo consists of three relatively flat layers of ectoderm, endoderm (also known as "entoderm") and mesoderm.
As the embryo develops, the mesoderm starts to segment into three main regions: the paraxial mesoderm, the intermediate mesoderm and the lateral plate mesoderm.
The lateral plate mesoderm later splits in half to form two layers bounding a cavity known as the intraembryonic coelom. Individually, each layer is known as splanchnopleure and somatopleure.
The intraembronic 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 the thorax and abdomen.
Layers of stomach wall. 1. Serosa; 2. Tela subserosa; 3. Muscularis; 4. Oblique fibers of muscle wall; 5. Circular muscle layer; 6. Longitudinal muscle layer; 7. Submucosa; 8. Lamina muscularis mucosae; 9. Mucosa; 10. Lamina propria; 11. Epithelium; 12. Gastric glands; 13. Gastric pits; 14. Villous folds; 15. Gastric areas
Section of duodenum of cat. X 60.
This wikipedia entry incorporates text from the freely licenced Connexions [1] edition of Anatomy & Physiology [2] text-book by OpenStax College
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| リンク元 | 「漿膜」 |
| 関連記事 | 「coat」「coated」「sero」「coating」「serous」 |