Serous membrane

Serous Membrane

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Serous membrane

In anatomy

Anatomy

Anatomy is a branch of biology that is the consideration of the body plan. It is a general term that includes human anatomy, animal anatomy and plant anatomy ....
, a serous membrane (or serosa) is a smooth membrane

Mesothelium

The mesothelium is a membrane that forms the lining of several body cavities: the pleura , peritoneum and pericardium . Mesothelial tissue also surrounds the male internal reproductive organs and covers the internal reproductive organs of women ....
consisting of a thin layer of cells

Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
which excrete serous fluid

Serous fluid

In physiology, the term serous fluid is used for various bodily fluids that are typically pale yellow and transparent, and of a benign nature, that fill the inside of body cavities....
. 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 not to be confused with adventitia

Adventitia

Adventitia is the outermost connective tissue covering of any Organ , Blood vessel, or other structure. It is also called the tunica adventitia....
, a connective tissue layer which binds together structures rather than reducing friction between them.

serous membrane is composed of a secretory epithelial

Epithelium

In biology and medicine, epithelium is a Biological tissue composed of cell s that line the cavities and surfaces of structures throughout the body....
layer and a connective tissue

Connective tissue

Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
layer underneath.

For the heart, the surrounding serous membranes include:

Other parts of the body may also have specific names for these structures.

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Encyclopedia

In anatomy

Anatomy

Mesothelium

Cell (biology)

Serous fluid

Adventitia

Structure

Each serous membrane is composed of a secretory epithelial

Epithelium

In biology and medicine, epithelium is a Biological tissue composed of cell s that line the cavities and surfaces of structures throughout the body....
layer and a connective tissue

Connective tissue

The epithelial layer, known as mesothelium
Mesothelium

The mesothelium is a membrane that forms the lining of several body cavities: the pleura , peritoneum and pericardium . Mesothelial tissue also surrounds the male internal reproductive organs and covers the internal reproductive organs of women ....
, consists of a single layer of avascular
Blood vessel

The blood vessels are the part of the circulatory system that transport blood throughout the body. There are three major types of blood vessels: the artery, which carry the blood away from the heart, the capillary, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from...
flat nucleated cells (simple squamous epithelium) which produce the lubricating serous fluid. This fluid has a consistency similar to thin mucus
Mucus

In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. It is a viscous colloid containing antiseptic enzymes and immunoglobulins that serves to protect Epithelium in the respiratory,...
. These cells are bound tightly to the underlying connective tissue.
The connective tissue layer provides the blood vessels and nerves 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 surrounding serous membranes include:

Outer	Inner >- \| Parietal pericardium Pericardium The pericardium is a double-walled sac that contains the heart and the roots of the great vessels....	Visceral pericardium (epicardium Epicardium Epicardium describes the outer layer of heart tissue . When considered as a part of the pericardium, it is the inner layer, or visceral pericardium.... )

Other parts of the body may also have specific names for these structures. For example, the serosa of the uterus

Uterus

The uterus is a major female hormone-responsive reproductive sex organ of most mammals, including humans. It is within the uterus that the fetus develops during gestation....
is called the perimetrium

Perimetrium

The perimetrium is the outer serosa layer of the uterus, equivalent to peritoneum.External links - "Mammal, uterus "...
.

The pericardial cavity

Pericardium

The pericardium is a double-walled sac that contains the heart and the roots of the great vessels....
(surrounding the heart

Heart

The heart is a muscle organ in all vertebrates responsible for pumping blood through the blood vessels by repeated, rhythmic contractions, or a similar structure in annelids, mollusks, and arthropods....
), pleural cavity (surrounding the lung

Lung

The lung is the essential respiration organ in air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located in the chest on either side of the heart....
s) and peritoneal cavity

Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
(surrounding most organs of the abdomen

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity....
) are the three serous cavities within the human body. It should be noted that 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.

Embryological origins

All serous membranes found in the human body formed ultimately from the mesoderm

Mesoderm

One of the three germ layers found in the embryos of animals more complex than cnidarians, making them triploblastic. Mesoderm forms in the embryo during gastrulation when some of the cells migrating inward to form the endoderm, produce an additional layer that lies between the endoderm and the ectoderm....
of the trilaminar embryo

Trilaminar embryo

A trilaminar embryo is an early stage in the development of triploblastic organisms, which include humans and many other animals.It is an embryo which exists as three different germ layers - the ectoderm, the mesoderm and the endoderm....
. The trilaminar embryo consists of three relatively flat layers of ectoderm

Ectoderm

The ectoderm is the start of a tissue that covers the body surfaces. It emerges first and forms from the outermost of the germ layers.Generally speaking, the ectoderm differentiates to form the nervous system, Epidermis , and the outer part of integumentary system....
, endoderm

Endoderm

Endoderm, is one of the germ layers formed during animal embryogenesis. Cells migrating inward along the archenteron from the inner layer of the gastrula, which develops into the endoderm....
(also known as "entoderm") and mesoderm

Mesoderm

Paraxial mesoderm

Paraxial mesoderm is the area of mesoderm that forms just lateral to the neural tube on both sides.It gives rise to the somitomeres/somites and mesoderm of the branchial arches....
, the intermediate mesoderm

Intermediate mesoderm

Intermediate mesoderm is a type of mesoderm that is located between the paraxial mesoderm and the lateral plate.It develops into the part of the urogenital system ...
and the lateral plate mesoderm

Lateral plate mesoderm

Lateral plate mesoderm is a type of mesoderm that is found at the periphery of the embryo....
.

The lateral plate mesoderm later splits in half to form two layers bounding a cavity known as the intraembryonic coelom

Intraembryonic coelom

The intraembryonic coelom is a a portion of the conceptus forming in the mesoderm. During the second week of development, the lateral mesoderm splits into a dorsal somatic mesoderm and a ventral splanchnic mesoderm ....
. Collectively, both layers are known as splanchnopleure

Splanchnopleure

In the anatomy of an embryo, the splanchnopleure is a structure created during embryogenesis when the lateral mesoderm splits into two layers. The inner layer adheres to the endoderm, and with it forms the splanchnopleure....
. Individually, each are known as visceropleure and somatopleure

Somatopleure

In the anatomy of an embryo, the somatopleure is a structure created during embryogenesis when the lateral mesoderm splits into two layers. The outer layer becomes applied to the inner surface of the ectoderm, and with it forms the somatopleure....
.

The visceropleure is associated with the underlying endoderm which it is in contact with, and later becomes the serous membrane in contact with visceral organs within the body.
The somatopleure is associated with the overlying ectoderm and later becomes the serous membrane in contact with the body wall.

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

Thorax

The thorax is a division of an animal's body that lies between the head and the abdomen.In mammals, the thorax is the region of the body formed by the sternum, the thoracic vertebrae and the ribs....
and abdomen

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity....
.

Additional images

External links

- "Tissues, Layers, and Organs: transverse section of rat gut" - "Uterus

Uterus

The uterus is a major female hormone-responsive reproductive sex organ of most mammals, including humans. It is within the uterus that the fetus develops during gestation....
" - "Jejunum

Jejunum

The jejunum is the middle section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms middle intestine or mid-gut may be used instead of jejunum....
"