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anatomyphysiologyblog - Connective Tissue: General Considerations

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Connective tissue provides a matrix that connects in addition to binds the cells in addition to organs in addition to ultimately gives back upward to the body. (Hence called back upward tissue also.)
The primary constituent of connexion tissue is the extracellular matrix. Due to this abundance of extracellular matrix, the cells inward connexion tissues are widely placed. Other tissues (like epithelium, muscular in addition to nervous) are formed mainly past times cells.

The role of connexion tissues:

Mechanical role i.e. supporting role equally described below:

  1. The Loose areolar tissue holds together structures similar skin, muscles, blood vessels etc. in addition to binds together the diverse layers of hollow viscera (stomach, intestine, urinary bladder, uterus).
  2. Reticular tissue forms a framework that supports the cellular elements of diverse organs similar spleen, lymph nodes in addition to glands.
  3. Enables the displace of peel over underlying structure.
  4. Allows mobility in addition to stretching inward hollow organs.
  5. Hold the os at joints (in the shape of ligament).
  6. Provide attachment for rootage in addition to insertions of many muscles (in the shape of deep fascia, intermuscular septa, aponurosis in addition to tendon). Tendon equally good transmits the push clitoris of muscles to their insertion.
  7. Hold the tendons of muscles at wrist in addition to talocrural articulation (in the shape of retinacula- thickened deep fascia).
  8. Provide planes along which blood vessels, lymphatics in addition to nerves locomote (through areolar tissue in addition to fascial membrane).
  9. Provides back upward in addition to protection to the encephalon in addition to spinal cord (in the shape of dura mater).


Other functions:

  1. The matrix serves equally medium through which nutrients in addition to metabolic wastes are exchanged betwixt cells in addition to their blood supply.
  2. Provides immunity: due to presence of cells of immune organization - macrophages in addition to plasma cells.
  3. Wound repair: Fibroblast produces the collagen fibres necessary for injure repair.
  4. Adipose tissue stores nutrition equally good equally provides insulation.
  5. Regeneration of tissues (like cartilage in addition to bone) due to the presence of undifferentiated mesenchymal cells. (Undifferentiated mesenchymal cells are capable of differentiating into specialized cells similar chondroblast-cartilage forming cells in addition to osteoblast- os forming cells)


Connective Tissues are broadly classified into:
General Connective tissue
Specialized connexion tissue (Bone, Blood, cartilage)

General Connective Tissue
The constituents for full general connexion tissues are equally follow:
Cells
Fibres
Ground substance

Cells

Fibroblast- these are the close numerous cells of connexion tissue. They are in addition to therefore named because they create collagen fibers (also reticular in addition to elastic fibers).In tissue sections, these cells look to live spindle shaped in addition to nucleus appears to live flattened. Fibroblast go rattling active when at that spot is require to lay downwards the collagen fibres e. g. during injure repair. Inactive forms are known equally fibrocytes.

Mesenchymal cell- Embryonic connexion tissue is known equally mesenchyme which is made upward of little cells alongside slender branching processes that bring together to shape a network. Various components of mature connexion tissue are derived from mesenchyme. Mesenchymal cells are capable of differentiating into whatever specialized cells. It is believed that some undifferentiated mesenchymal cells persist equally such in addition to these are the cells from which other types tin sack live formed when required.

Pigment cells- they are easily distinguished equally they comprise chocolate-brown paint (melanin) inward their cytoplasm. They are close abundant inward the connexion tissue of skin, of choroid in addition to iris of eyeball. Of the many cells that comprise paint inward their cytoplasm entirely a few are truly capable of synthesizing melanin. Such cells are called melanocytes, remaining cells are those that engulf paint released past times other cells. Such cells are called chromatophores or melanophore in addition to are likely modified fibroblasts.

Fat cells or adipocytes- some cells shop fatty inward large amounts in addition to go distended alongside it. These are called fatty cells, adipocytes or lipocytes.

Mast cells- these are little circular or oval cells. The nucleus is little in addition to centrally placed. The distinguish characteristic of these cells is the presence of numerous granules inward the cytoplasm. They unloose diverse substances when appropriately stimulated e.g. unloose of histamine is associated alongside allergic reaction when a tissue is exposed to an antigen to which it is sensitive. They are close often seen unopen to blood vessels in addition to nerves.

Macrophages- these cells are component of mononuclear phagocyte system. Macrophage cells of connexion tissue are equally good called histiocytes or clasmatocytes. They convey might to phagocytose unwanted textile similar bacteria invading the tissue in addition to damaged tissues. Fixed macrophages resemble fibroblast but gratuitous or motile macrophages are round. The nuclei of macrophages are little in addition to stain intensely than those off fibroblasts.

Lyhmphocytes-lymphocytes stand upward for 1 multifariousness of leukocytes in addition to are inward aggregation inward lymphoid tissues. They attain connexion tissue from these sources in addition to are numerous when tissue undergoes inflammation. They convey the might to recognize the substances that are unusual to host torso in addition to destroy them past times producing antibodies against them. They are of 2 types B lymphocytes in addition to T lymphocytes.

Plasma cells- rattling few plasma cells tin sack live seen inward normal connexion tissue. Their number increases inward the presence of sure enough types of inflammation. These are mature B lymphocyte that convey lost their might of farther division. Plasma cells is seen to live little in addition to rounded alongside nucleus having auto cycle resemblance. The cytoplasm is basophilic.

Fibers

Collagen –Collagen fibers are close abundant. With lite microscopy they are seen inward bundles. the bundles are made upward of collections of private collagen fibers which are 1-12 micrometer inward diameter. In plough collagen fibers are made upward of fibrils which are 20-200 nm inward diameter. Each fibril consists of a number of microfibrils, 3.5 nm inward diameter.

Bundle of collagen fibers look white alongside naked eye. With H & E, they are stained lite pink.
Collagen fibers tin sack resist considerable tensile forces without significance increment inward their length. They are equally good pliable in addition to tin sack curvature easily.

Chemically collagen fibers are made upward of poly peptide called collagen.

Types of Collagen fibers

Type I- they are constitute inward connexion tissue, tendons, ligaments, fasciae, aponeurosis, bone, dermis, meninges etc.
Type II- constitute inward hyaline cartilage, vitreous body.
Type III is the reticular fibres
Type IV- inward the basal laminae of basement membrane.
Various other types are equally good recognized.

Elastic fiber- Elastic fibers are made upward of a poly peptide called elastin. They run singly (not inward bundles), branch in addition to anastomose alongside other fibers. Elastic fibers are thinner than those of collagen (0.1-0.2 micrometer). In some province of affairs they are thick e.g. ligamentum flava in addition to inward other they are fenestrated equally inward walls of arteries.

Elastic fibers tin sack live stretched (like a safe band) in addition to returns to their master copy length when tension is released. They are seen equally shining work inward unstained preparations.

Reticular fiber- these fibers are multifariousness of collagen fiber (Type III). They are much finer in addition to uneven inward thickness. They shape a network (or reticulum) past times branching in addition to anastomosing alongside each other. They attain non run inward bundles. Reticular fibers provide a supporting network inward many situations e.g. spleen, lymph nodes in addition to os marrow; close glands including liver; in addition to the kidneys. They are the essential factor of all basement membrane.

Ground substance
The intercellular Blue Planet marrow is a highly hydrated, complex mixture of glycosaminoglycans, proteoglycans in addition to multiadhesive glycoproteins. The complex molecular mixture of the Blue Planet marrow is colorless in addition to transparent, it fills the infinite betwixt cells in addition to fibers of the connexion tissue in addition to because it is glutinous acts equally both a lubricant in addition to a barrier to the invaders.

Glycosaminoglycans (GAGs) are linear polysaccharides formed past times repeating disaccharide units commonly composed of uronic acid in addition to a hexosamine. The hexosamine tin sack live glucuronic or iduronic acid. With exception of hyaluronic acid, these linear chains are bounded covalently to a poly peptide core, forming a proteoglycan molecule. Because of abundance of hydroxyl, carboxyl in addition to sulfate groups inward the saccharide moiety of close GAGs, the GAGs are intensely hydrophilic in addition to acts equally polyanions. With the exception of hyaluronic acid, all other GAGs are sulfated to some score inward adult state. The carbohydtrate part of proteoglycans constitutes 80-90% of this molecule.

Types of Connective tissue
Loose areolar- e.g. superficial fascia
Dense irregular – e.g. dermis of the skin
Dense regular- e.g. tendon
Elastic Tissue- e.g.  ligamentum flava
Adipose Tissue

REFERENCES:
Following resources are used patch preparing this ship (readers are strongly recommended to go through them for to a greater extent than details):

Wheater's Functional Histology: H5N1 Text in addition to Color Atlas
Junqueira's Basic Histology: Text in addition to Atlas