What Type of Membrane Lines Cavities That Open to the Outside of the Body?
| Serous Membrane | |
|---|---|
 Stomach. (Serosa is labeled at far right, and is colored xanthous.) | |
| Details | |
| Precursor | mesoderm |
| Identifiers | |
| Latin | tunica serosa |
| MeSH | D012704 |
| FMA | 9581 |
| Anatomical terminology [edit on Wikidata] | |
Serous membrane lines the pericardial cavity and reflects back to cover the eye—much the same way that an underinflated airship would form two layers surrounding a fist.[1]
In anatomy, serous membrane (or serosa) is a smooth tissue membrane of mesothelium lining the contents and inner walls of body cavities, which secrete serous fluid to allow lubricated sliding movements between opposing surfaces. The serous membrane that covers internal organs is called a visceral membrane; while the 1 that covers the cavity wall is called the parietal membrane. Between the ii opposing serosal surfaces is often a potential space, generally empty except for the pocket-size amount of serous fluid.[2]
The Latin anatomical proper noun is tunica serosa. Serous membranes line and enclose several body cavities, also known as serous cavities, where they secrete a lubricating fluid which reduces friction from movements. Serosa is entirely different from the adventitia, a connective tissue layer which binds together structures rather than reducing friction betwixt them. The serous membrane covering the centre and lining the mediastinum is referred to every bit the pericardium, the serous membrane lining the thoracic cavity and surrounding the lungs is referred to every bit the pleura, and that lining the abdominopelvic cavity and the viscera is referred to equally the peritoneum.
Structure [edit]
Serous membranes have two layers. The parietal layers of the membranes line the walls of the torso cavity (pariet- refers to a crenel 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 infinite, or cavity.[3]
Visceral and parietal layers [edit]
Each serous membrane is composed of a secretory epithelial layer and a connective tissue layer underneath.
- The epithelial layer, known every bit mesothelium, consists of a single layer of avascular flat nucleated cells (simple squamous epithelium) which produce the lubricating serous fluid. This fluid has a consistency similar to thin fungus. These cells are spring tightly to the underlying connective tissue.
- The connective tissue layer provides the claret vessels and fretfulness for the overlying secretory cells, and also serves as the binding layer which allows the whole serous membrane to adhere to organs and other structures.
For the heart, the layers of the serous membrane are called the parietal pericardium, and the visceral pericardium (sometimes called the epicardium). Other parts of the torso may also have specific names for these structures. For instance, the serosa of the uterus is called the perimetrium.
Schematic diagram of an organ invaginating into a serous cavity
The pericardial cavity (surrounding the heart), pleural crenel (surrounding the lungs) and peritoneal cavity (surrounding most organs of the abdomen) are the three serous cavities within the homo trunk. 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 role 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 exercise non lie inside 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 torso wall.
Examples [edit]
In the human body, there are 3 serous cavities with associated serous membranes:
- A serous membrane lines the pericardial cavity of the centre, and reflects back to comprehend the heart, much similar an under-inflated balloon would course two layers surrounding a fist. Called the pericardium, this serous membrane is a two-layered sac that surrounds the entire heart except where blood vessels emerge on the eye'southward superior side;[three]
- The pleura is the serous membrane that surrounds the lungs in the pleural cavity;
- The peritoneum is the serous membrane that surrounds several organs in the abdominopelvic cavity.
- The tunica vaginalis is the serous membrane, which surrounds the male gonad, the testis.
The two layers of serous membranes are named parietal and visceral. Betwixt the two layers is a sparse fluid filled space.[iii] The fluid is produced past the serous membranes and stays between the two layers to reduce friction betwixt the walls of the cavities and the internal organs when they move with respect to one some other, such equally when the lungs inflate or the heart beats. Such motility could otherwise atomic number 82 to inflammation of the organs.[3]
Evolution [edit]
All serous membranes found in the human being body formed ultimately from the mesoderm of the trilaminar embryo. The trilaminar embryo consists of three relatively apartment layers of ectoderm, endoderm (as well known equally "entoderm") and mesoderm.
As the embryo develops, the mesoderm starts to segment into iii main regions: the paraxial mesoderm, the intermediate mesoderm and the lateral plate mesoderm.
The lateral plate mesoderm after splits in one-half to form ii layers bounding a crenel known as the intraembryonic coelom. Individually, each layer is known as splanchnopleure and somatopleure.
- The splanchnopleure is associated with the underlying endoderm with which it is in contact, and afterwards becomes the serous membrane in contact with visceral organs inside the body.
- The somatopleure is associated with the overlying ectoderm and later becomes the serous membrane in contact with the body wall.
The intraembryonic 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 inside the thorax and abdomen.
Anatomical images [edit]
-
Layers of stomach wall
-
Section of duodenum of cat
See as well [edit]
- Adventitia
References [edit]
This Wikipedia entry incorporates text from the freely licensed Connexions [1] edition of Anatomy & Physiology [two] text-book by OpenStax College
- ^ J. Gordon Betts, Kelly A. Immature, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Marking Womble, Peter DeSaix (April 25, 2013). "i.6 Anatomical Terminology". Anatomy and Physiology. Houston, Texas: OpenStax.
{{cite book}}: CS1 maint: uses authors parameter (link) - ^ "The Beefcake of Lining and Covering Tissues-Membranes!". McGraw-Colina Companies. Retrieved September 2, 2017.
- ^ a b c d "Anatomy & Physiology". Openstax higher at Connexions. Retrieved November 16, 2013.
External links [edit]
- UIUC Histology Subject 844
- Parsons, Frederick Gymer (1911). . Encyclopædia Britannica. Vol. 6 (11th ed.). pp. 642–644.
Source: https://en.wikipedia.org/wiki/Serous_membrane
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