Loose connective tissue
Connective tissue | |
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Section of dermis. The papillary dermis consists of loose connective tissue. | |
Details | |
Identifiers | |
Latin | textus connectivus laxus |
TA |
A04.5.02.020 A16.0.03.006 |
TH | H2.00.03.1.00002 |
FMA | 19783 |
Anatomical terminology |
Loose connective tissue is a category of connective tissue which includes areolar tissue, reticular tissue, and adipose tissue. Loose connective tissue is the most common type of connective tissue in vertebrates. It holds organs in place and attaches epithelial tissue to other underlying tissues. For example, it forms telae, such as the tela submucosa and tela subserosa, which connect mucous and serous membranes to the muscular layer. It also surrounds the blood vessels and nerves. Cells called fibroblasts are widely dispersed in this tissue; they are irregular branching cells that secrete strong fibrous proteins and proteoglycans as an extracellular matrix. The cells of this type of tissue are generally separated by quite some distance by a gelatinous substance primarily made up of collagenous and elastic fibers.
Loose connective tissue is named based on the weave and type of its constituent fibers. There are three main types of connective tissue fiber:
- Collagenous fibers: collagenous fibers are made of collagen and consist of bundles of fibrils that are coils of collagen molecules.
- Elastic fibers: elastic fibers are made of elastin and are "stretchable."
- Reticular fibers: reticular fibers consist of one or more types of very thin collagen fibers. They join connective tissues to other tissues.
Usually "loose connective tissue" is considered a parent category that includes the mucous connective tissue of the fetus, areolar connective tissue, reticular connective tissue, and adipose tissue.[1]
Structure
Composition
It is a pliable, mesh-like tissue with a fluid matrix and functions to cushion and protect body organs.
Fibroblasts are widely dispersed in this tissue; they are irregular branching cells that secrete strong fibrous proteins and proteoglycans as an extracellular matrix.
The cells of this type of tissue are generally connected by a gelatinous substance known as ground substance primarily made up of collagenous and elastic fibers.
Location
It may be found in tissue sections from almost every part of the body. It surrounds blood vessels and nerves and penetrates with them even into the small spaces of muscles, tendons, and other tissues. It may likewise be present in the mediastinal extremities. Nearly every epithelium rests on a layer of areolar tissue, whose blood vessels provide the epithelium with nutrition, waste removal, and a ready supply of infection-fighting leukocytes in times of need. Because of the abundance of open, fluid-filled space, leukocytes can move about freely in areolar tissue and can easily find and destroy pathogens.
The areolar tissue is found beneath the dermis layer and is also underneath the epithelial tissue of all the body systems that have external openings.
It is also a component of the lamina propria of the digestive and respiratory tracts, the mucous membranes of reproductive and urinary systems, the stroma of glands, and the hypodermis of the skin. It is also found in the mesentery which is surrounding the intestine.
Classification
Loose connective tissue is named based on the "weave" and type of its constituent fibers. There are three main types:
- Collagenous fibers: collagenous fibers are made of collagen and consist of bundles of fibrils that are coils of collagen molecules.
- Elastic fibers: elastic fibers are made of elastin and are "stretchable."
- Reticular fibers: reticular fibers consist of one or more types of very thin collagen fibers. They join connective tissues to other tissues.
Areolar tissue
Areolar tissue (/əˈriːələr/ or /ˌɛəriˈoʊlər,
Function
Areolar connective tissues hold organs in place and attaches epithelial tissue to other underlying tissues. It also serves as a reservoir of water and salts for surrounding tissues. Almost all cells obtain their nutrients from and release their wastes into areolar connective tissue.
Clinical significance
Organs that are rich in loose connective tissue(such as the eyelids) are usually sites that undergo oedema indicating renal failure or nephrotic syndrome. Thus periorbital swelling is one characteristic finding in severe renal disease
See also
References
- ↑ "Blue Histology - Connective Tissues". Retrieved 2008-12-05.
- ↑ "Areolar". Merriam-Webster Dictionary. Retrieved 2016-01-21.
- ↑ "Areolar". Oxford Dictionaries. Oxford University Press. Retrieved 2016-01-21.
- ↑ "areolar tissue" at Dorland's Medical Dictionary