Loose connective tissue | |
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Details | |
Identifiers | |
Latin | textus connectivus laxus |
Code | TH H2.00.03.1.00002 |
TA |
A04.5.02.020 A16.0.03.006 |
FMA | 19783 |
Anatomical terminology
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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 , 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:
Areolar tissue (/əˈriːələr/ or /ˌɛəriˈoʊlər, ˌær-/) is a common type of loose connective tissue (and the most widely distributed type of connective tissue in vertebrates). It is so named because its fibers are far enough apart to leave ample open space for interstitial fluid in between ( is Latin for a "little open space"). It is strong enough to bind different tissue types together, yet soft enough to provide flexibility and cushioning. It exhibits interlacing, loosely organized fibers, abundant blood vessels, and significant empty space filled with interstitial fluid. Many adjacent epithelial tissues (which are avascular) get their nutrients from the interstitial fluid of areolar tissue; the lamina propria is areolar in many body locations. Its fibers run in random directions and are mostly collagenous, but elastic and reticular fibers are also present. Areolar tissue is highly variable in appearance. In many serous membranes, it appears as a loose arrangement of collagenous and elastic fibers, scattered cells of various types; abundant ground substance; numerous blood vessels. In the skin and mucous membranes, it is more compact and sometimes difficult to distinguish from dense irregular connective tissue.