Author: Jana Vasković•Reviewer: Nicola McLaren MScLast reviewed: September 05, 2021Reading time: 12 minutes


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Connective tissue is the tconcern that connects, sepaprices and supports all various other forms of tissues in the body. Like all tproblem kinds, it is composed of cells surrounded by a compartment of liquid called the extracellular matrix (ECM). However connective tconcern differs from various other types in that its cells are loosely, fairly than tightly, packed within the ECM. 

Based on the cells current and the ECM framework, we differ 2 forms of connective tissue:

Connective tworry proper; additionally divided into loose and thick connective tissuesSpecialised connective tissue; reticular, blood, bone, cartilage and adipose tissues

We know that there are means cooler histology topics than connective tworry, like muscle tissue or neural tconcern. But as the connective tissue is the glue that holds all various other tproblems together, it has actually the essential attribute of ensuring that our body systems work in harmony.

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Key facts
Dense connective tissueCells: fibroblastsFibers: collagen fibers greatly packed in the ECM either in parallel order (dense regular), or randomly interlaced (dense irregular)
Loose connective tissueCells: fibroblastsFibers: collagen fibers loosely scattered in the ECM
Reticular connective tissueCells: reticular cellsFibers: reticular fibers organized in breakable networks
CartilageCells: chondrocytesECM: collagen II (hyaline cartilage), elastic fibers (elastic cartilage), collagen I (fibrocartilage)
BoneCells: osteoblasts, osteocytes, osteoclastsECM: calcified lamellae
BloodCells: erythrocytes, leukocytes, plateletsECM: blood plasma
Adipose tissueCells: white and brown adipocytesECM: no ECM
Embryonic connective tissueMesenchyme: mesenchymal cells in reticular fibers rich ECMMucoid tissue: mesenchymal cells in collagen rich ECM

This page will describe what is connective tworry and also existing you via an introduction of its types. 


Contents
Connective tworry correct Specialized connective tissues
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Cells and also fibers of connective tissue

The three components of connective tworry are cells, ground substance and fibers. Ground substance and fibers consist of the extracellular matrix (ECM).


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The major cell of connective tissue is the fibroblast. Its attribute is to develop and maintain the ECM of connective tconcern. Besides fibroblasts, several other cell types are current. These are the cells of the immune system (macrophages, lymphocytes and mast cells) and adipocytes. Specialised connective tconcern has specialised cells, for instance cartilage consists of chondrocytes and also bone consists of osteocytes. 

Ground substance is a viscous gel made of water, proteoglycans, glycoproteins and also glycosaminoglycans. These make the ground substance viscous and also bind high quantities of water which enables hydration, diffusion of nutrients and also nourishing of the tproblem.

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Tright here are 3 forms of protein fibers; collagen, elastic and reticular. Collagen fibers and also reticular fibers both belong to the collagen family, of which tright here are over 20 different forms. Collagen fibers are predominantly made of collagen type I. These are the the majority of numerous protein fiber type, providing differing levels of strength and rigidity to tconcerns.

Reticular fibers consist of collagen kind III, they are thin delicate fibers that create meshfavor netfunctions in organs such as the spleen, kidneys and also lymph nodes. Elastic fibers are made from the protein elastin, giving extending and bending properties to tworries. They are mainly discovered within the wall surfaces of huge blood vessels, elastic cartileras, yellow ligaments, lungs and also skin. Variations in the cell and also protein fiber combicountries and arrangements bring about the different kinds of connective tissue.

Connective tconcern proper

Connective tissue correct is uncovered throughout the entire body. There are two subtypes of connective tconcern proper; loose and also regular. They differ in the structural layout of their extracellular matrix. 

Loose connective tissue

Loose connective tissue is also called the areolar connective tconcern. It has nearly equal quantities of cells, fibers and ground substance. Chief cells are the fibroblasts. However before, immune device cells are likewise existing. Collagen fibers are the major fibers of the ECM. They are sparsely distributed within the ECM, which is why this tissue kind is called ‘loose’. Besides the collagen fibers, moderate quantities of reticular and elastic fibers are present also. 


Loose connective tissue is the most widely distributed form of connective tconcern, discovered in the lining of the body"s inner surdeals with. The cell to fiber combicountry renders loose connective tconcern flexible however not exceptionally resistant to mechanical anxiety. This enables the tissue to play an important function in binding various other tconcern types together, for instance joining tconcerns into organs, holding organs in location and attaching epithelial tconcern to various other tissue types. The visibility of immune system cells adds an immuno-protective connective tissue function. Instances of loose connective tworry include; the lamina propria of the alimentary and respiratory tracts, mucous membranes of refertile and urinary tracts, glands, mesentery and dermis of the skin.

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Dense connective tissue


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Dense connective tissue has fewer cells than loose. Instead, its ECM is densely packed with collagen fibers. Based on the setup of the fibers, tright here are 2 subtypes of thick connective tissue; dense continual and also dense ircontinuous. Dense consistent connective tconcern has actually the collagen fibers aligned parallel to each various other. This setup gives the tissue with high unidirectional resistance to stress. The finest thick continuous connective tproblem examples are the tendons and also ligaments. Dense ircontinual connective tissue has actually collagen fibers randomly interwoven, developing a three-dimensional network resistant to disanxiety in all directions. It is generally located in the capsules and also wall surfaces of the organs, the dermis of the skin and glands.

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Specialized connective tissues

Reticular connective tissue


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Reticular connective tissue is developed by modified fibroblasts referred to as reticular cells. These create reticular fibers arranged in an interlaced network (reticulum), similar to thick ircontinual connective tproblem. The distinction between them is that the reticular fibers are thinner, create a more breakable mesh, via reticular cells remaining bonded to the fibers.

Reticular tworry supports the stroma of body organs, particularly lymphoid. Reticular meshes filter lymph and also provide a microsetting for the passage and attachment of white blood cells. Hence, it is present in red bone marrow, lymph nodes and the spleen.

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Cartilage


Cartilage is the avascular connective tproblem that connects bones at joints and comprises walls of top respiratory airways and also external ear. It is surrounded by perichondrium, a layer of dense connective tproblem. The perichondrium is wealthy in blood vessels and gives the cartilage. Chief cells in cartilage are chondrocytes, lodged into cavities within the ECM referred to as lacunae. The ECM is vast, wealthy in water bound to glycosaminoglycans. This ECM structure makes cartilage functional in miscellaneous degrees but long lasting to mechanical anxiety.

Tright here are 3 types of cartilage;

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Bone


Bone is the tconcern that comprises the body skeleton. Like all connective tconcerns, bone is created of cells within an extracellular matrix of fibers (predominantly collagen form 1) and also ground substance. The extracellular bone matrix is mineralized and arranged in circular layers referred to as lamellae. These lamellae circumvent approximately a main canal (Haversian canal) which serve for the passage of neurovasculature that supplies the bone and also house the cells.

Bone ECM is produced and also maintained by a number of cells; osteoblasts, osteocytes and also osteoclasts. Osteoblasts are cells that actively create the bone matrix. When dormant, they are dubbed osteocytes. Osteoclasts perform the opposite; they absorb the bone matrix. Synchronized function of these cells is necessary for the recoincredibly of broken bones (bone remodeling) and also for the general well being of the skeletal device. The specialised cell and ECM nature of bone permits it to serve as a storage site for calcium and phosphate, alongside its weight bearing and also protection functions.

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Blood


Blood is the specialized connective tworry within the circulatory device that transports blood cells and liquified substances throughout the body via blood vessels. As all connective tproblem, it has actually cellular and also extracellular components.The extracellular matrix of the blood is called blood plasma. It is composed of water and solutes (proteins, electrolytes, nutrients, gases, hormones and waste products). The blood cells, likewise dubbed the created elements, brought by plasma are the erythrocytes (red blood cells), leukocytes (white blood cells) and also thrombocytes (platelets). These cells are created in the bone marrowhead in the procedure of hematopoiesis.


Adipose tissue

Adipose tissue is the energy-storing connective tproblem. It is composed of adipocytes, cells filled with lipids (fats). This tworry has a little amount of ECM made of only a few collagen fibers that save the cells together. Depending on how the lipids are spread within the cell; tright here are white and also brown adipose tissues.


In brvery own adipose tissue each cell includes multiple fat drops, neighboring the centrally positioned nucleus. This kind is typically discovered in babies wright here rather of energy-storing it serves for thermogenesis (heat production). In white adipose tworry the lipid is accumulated into a solitary large droplet, which presses the organelles versus the cell membrane.

White adipose tissue is predominant discovered in adults. It stores energy, cushions and also protects organs, and acts as an endocrine organ by secreting hormones. White adipose tworry distributes into visceral and also parietal fats. Visceral fats surround and also support the body organs, such as eyeballs (periorbital fat) and also kidneys (perinephric fat). Parietal fats are aggregations embedded in the connective tconcern proper of the skin, typically in the abdominal, ago and also thigh areas.

Embryonic connective tissue


Embryonic connective tworry is uncovered in the at an early stage embryos and umbilical cord. Chief cells are mesenchymal cells. It is separated into mesenchyme (in embryos) and mucoid connective tconcern (umbilical cord).

Mesenchyme originates from mesoderm, among the three germiindigenous layers in embryos. It matures into other kinds of connective tworries, muscles, vessels, mesothelium and the urogenital system. Its mesenchymal cells are spread within ECM filled mainly with reticular fibers. Mucoid connective tissue is found in the umbilical cord. Its mesenchymal cells are loosely dispersed within a collagen affluent ECM dubbed Wharton’s jelly. 


Rundown and also kinds of connective tissue: want to learn even more about it?

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