Post on 05-Apr-2018
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CONNECTIVE TISSUEGROUP 3
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WHAT IS CONNECTIVE TISSUE?
is a diverse group of tissues
derived from embryonic mesenchyme
it forms an extensive compartment in the body, can beconsidered as the "glue" that holds the body together
Specialized connective tissue :
(adipose tissue; cartilage; bone; blood and hematopoietictissue )
consists of individual cells scattered within an
extracellular matrix.
Ground substance Fibers
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ADIPOSE
HYALINE ELASTIC FIBRO
CARTILAGE
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BONE
SPONGY
3 Neutrophils & 1Basophils
BLOOD
COMPACT
Eusinophil & FewPlatelets
MONOCYTES LYMPHOCYTE
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THE GROUND SUBSTANCE
The translucent material in which the cells andfibers of connective tissue are embedded.
Major polysaccharides
Glycosaminoglycans
a class of macromolecules that arelong, linear polymers ofdisaccharide. Major GAGs
Condroitin sulfate
Keratan sulfate
Heparan sulfate
Hyalunoric acid
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FIBERS
TYPES : collagen fibers
reticular fibers
elastic fibers
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COLLAGEN FIBERS
most common fiber type
collagen fibers are seen to be made up of thread-likesubunits called
present in all kinds of tissue These are flexible fibers with a high tensile
strength
collagen fibrils.
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COLLAGEN FIBERS
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COLLAGEN FIBERS
12 TYPES :
TYPE I
TYPE II
TYPE III
TYPE IV
TYPE V
TYPE VI
TYPE VII
TYPE VIII
TYPE IX
TYPE X
TYPE XI
TYPE XII
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COLLAGEN FIBERS
TYPE I the most ubiquitous
fibers are flexible but offer great resistance to tension
occuring in the Dermis
Bone
Tendon
Fascia
In the capsules of organs
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this specimen shows the appearance of type i collagen
fibers under the electron microscope. these fibers show
a characteristic banding pattern which results from theoverlap of the tropocollagen constituents. the periodicity
of this pattern is typically 64 nanometers.
http://medcell.med.yale.edu/histology/connective/collagen_fibers_em.phphttp://medcell.med.yale.edu/histology/connective/collagen_fibers_em.phphttp://medcell.med.yale.edu/histology/connective/collagen_fibers_em.phphttp://medcell.med.yale.edu/histology/connective/collagen_fibers_em.php7/31/2019 Group 3 - Connective Tissue
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COLLAGEN FIBERS
TYPE II :Forms very thin fibrils that are embedded in ana
bundant ground substance found in the :
Hyaline
Elastic cartilage Nucleus pulposus of the intervetebral discs
Vitreous body of the eye
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COLLAGEN FIBERS
TYPE III :Forms argyrophilic fibers called reticular fibers
abundant in:
Loose connective tissue walls of blood vessels
stroma of various glands
Spleen
Kidney Uterus
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COLLAGEN FIBERS
TYPE IVSpecialized form largely restricted to the basal lamina of
epithelia
TYPE V
Widespread occurrence but is present only in very smallamounts
TYPE VIPresent in small amounts at most sites where types I & III
are found
TYPE VII assoc. w/ the basal lamina of many epithelia but is most
abundant at the dermo-epidermal kunction of the skin
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COLLAGEN FIBERS
TYPE VIII Secretory product of endothelial cells growing in vitro ,sometimes called
endothelial collagen Major component of descemets membrane, the typical basal lamina of
the corneal epithelium
TYPE IX Found mainly in cartilage
TYPE X Confined to cartilage Found in the matrix immediately surrounding hypertrophic
chondrocytes involved in endochondral bone formation TYPE XI
Associated with type II collage in cartilage
TYPE XII
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RETICULAR FIBERS
They provide a supporting framework for thecellular constituents of various tissues andorgans
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FIBRILLIN
is defective or deficient in MARFANSYNDROMEA heritable disease of connective tissue,
characterize by excessively long arms & legs & a
progressive dilatation of the ascending aorta thatmay lead to fatal rupture.
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ELASTIC FIBERS
give tissue the ability to cope with stretch and distension.
interwoven w/ collagen fibers to limit distensibility & toprevent tearing.
2 large amino acids unique to elastin
Desmosine isodesmosine
2 structural components
Elastincauses collagen to coil in a random way
Microfibrils
consist of a fibrillar glycoprotein
In developing elastic tissue, they appear before the elastin, and arebelieved to serve as an organizing structure for it.
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ELASTIC FIBERS
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ADHESION GLYCOPROTEINS
It is the attachment of other cell types.
Examples of adhesion glycoprotein are:
Fibronectin
Laminin Thrombospondin
They have binding sites for cell membrane and for collagen.
FUNCTION: maintain adhesion of cells to their substrate.
they also influence the state of differentiation of the cells.
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FIBRONECTIN
is a high-molecular weight (~440kDa)glycoprotein of the extracellular matrix thatbinds to membrane-spanning receptor
proteins called integrins.
It is synthesized by connective tissue
fibroblasts because it is not directly visible bymicroscopy.
http://en.wikipedia.org/wiki/Integrinshttp://en.wikipedia.org/wiki/Integrins7/31/2019 Group 3 - Connective Tissue
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FIBRONECTIN
It has long flexible fibronectin molecule forcell-binding, and collagen-binding domainsalong its length.
connecting the surface of the cells to the fibrousand amorphous components of the extracellularmatrix.
PLASMA FIBRONECTIN synthesized by the liver cell and endothelial cells.
Binds to fibrin and may have a significant role in bloodclotting
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LAMININ
Has a molecular weight of one (1) million.
It is a trimeric proteins that contain an -chain, a -chain, and a -chain, found in five,four, and three genetic variants, respectively.
It is a cross-shaped molecule with rod-likeand globular regions.
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It is synthesized by connective tissuefibroblast.
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THROMBOSPONDIN
Is an adhesive glycoprotein of 450,000 MW
First identified as a product of activatedplatelets, secreted during blood clotting.
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ORIGIN OF CONNECTIVE TISSUE FIBERS
Connective tissue fibers are produced byfibroblast. large, flat, branching cells which appear spindle-
shaped in a side view.
Connective tissue fibers are composed ofstructural proteins. The three main types offibers are: collagen fibers reticular fibers elastic fibers
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CELLS OF CONNECTIVE TISSUE
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CELLS OF CONNECTIVE TISSUE (CATEGORIES)
Fixed Cells these are relatively stablepopulation of long-lived cells that include thefibroblastsecrete and maintain the
extracellular components and adipose cellsthat store and release lipids to be used as anenergy source in the metabolism of other
cells throughout the body.
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CELLS OF CONNECTIVE TISSUE (CATEGORIES)
Free cellsare a changing population ofmotile cells that enter the connective tissuefrom the blood and wander through its
ground substance.
Most of these are short lived and are
continually replaced from the large pool ofcells of the same type circulating in theblood.
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MESENCHYMAL CELLS
The connective tissues develop from theembryonic tissue called mesenchyme.
Mesenchymal cells are small fusiform orstellate cells not easily distinguised fromfibroblasts.
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MESENCHYMAL CELLS
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FIBROBLAST
These are cells that produce the extracellularcomponents of developing connective tissue.
When they become relatively inactive in fiber
formation , some histologist prefer to callthem fibrocytes.
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FIBROBLAST
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FIBROCYTES
The shape of these cells depends , to someevents, on the nature of their substrate.
They are usually deployed along bundles of
collagen fibers and appear in sections,as afusiform cells with long tapering ends.
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FIBROCYTES
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FIBROBLAST (FUSIFORM)
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FIBROBLAST
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FIBROBLAST
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ADIPOSE CELLS
Adipose cells or fat cells are fixed cells of theconnective tissue specialized for thesynthesis and storage of lipid.
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ADIPOSE CELLS
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ADIPOSE TISSUE (WHITE FAT)
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MACROPHAGES
Also known as the histiocytes.
It plays a role in the maintenance of normaltissues by ingesting dead cells and cellular
debris and other particulate matter andbreaking them down with their lysosomalenzymes.
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MACROPHAGES
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MACROPHAGES
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MACROPHAGES(CATEGORIES)
Free macrophages motile cells of varyingshape that wandered through the groundsubstance.
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MACROPHAGES (CATEGORIES)
Fixed macrophages sessile cells that werestretched out along collagen fibers and had ashape not unlike that of fibroblast.
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FREE CELLS OF
CONNECTIVE TISSUE
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Monocytes are rarely found in connectivetissue for, on leaving the bloodstream.
They respond to chemotactic metabolicproducts of bacteria by congregating at thesite.
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Phagocytes must be derived from bone
marrow stem cells, have a characteristicmorphologic features, and exhibit relativelyintense phagocytic activity mediated byimmunoglobulin or serum complement.
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Metchnikoff proposed the termmacrophage system.
Aschoff suggested the termreticuloendothelial system.
Van Furth introduced the term
mononuclear phagocyte system.
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Neutrophils are rarely found in normalconnective tissue but they are included here,among its free cells.
Endothelial Cell Adhesion Molecule-1 (ELAM-1)makes their lumenal surface sticky.
Leukocyte adhesion molecules (LeuCAMs)
promote their adhesion to the sticky capillary
endothelium.
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EOSINOPHIL LEUKOCYTES
Eosinophils are normal constituents of theconnective tissue.
They are numerous in the connective tissueof the nasal cavity, lungs, skin and laminapropria of the intestine than they areelsewhere.
Eosinophil Cationic Protein (ECP)appears to be incorporated in themembrane of the target parasite.
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Lymphocytes which are the principalagents of the immune system, found in
small numbers in the connective tissuethroughout the body.
They function in protective immuno-surveillance against the rich bacterial flora inthe lumen of the gut.
Endothelial cell adhesion molecules(also called addressins or selectins) serve
as homing receptors binding lymphocytes. Two kinds of Lymphocytes:
T-lymphocytes
B-lymphocytes
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Plasma Cells are few in number inconnective tissues in most areas of
the body. Responsible for thesynthesis of the antibodies found inthe bloodstream.
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Mast Cells are the largest of the free cells ofthe connective tissue and are easily identifiedby the numerous basophilic granules in theircytoplasm, which may obscure the nucleus.
- oval to round connective tissue, whosecytoplasm is filled with basophilic granules.
Basophils are smaller and usually have abilobed nucleus. They are found only in theblood and, like other granular leukocytes.
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The major cavities of the body are lined byserous membrane:
The peritoneumlining of the abdominal cavity,and the pleuralining the thoracic cavity.
Consist of a thin layer of typical looseconnective tissue covered by mesothelium. Mesothelium a squamous epithelium of
mesodermal origin. Thin sheet-like. Omentum a large free fold of visceral
peritoneum that hangs, like a curtain.
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VARIANT TYPES OF LOOSE CONNECTIVE TISSUEReticular Connective Tissue
Mucous Connective Tissue
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RETICULAR CONNECTIVE TISSUE
- cells tend to be stellate with slender radiatingprocesses
- they are NOT considered to be a distinct celltype, but merely FIBROBLASTS
- forms the stroma of the bone marrow andthat of the spleen, lymph nodes and thymus
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MUCOUS CONNECTIVE TISSUE
- very large amount of amorphous groundsubstance that is rich in hyaluronic acid
- rare in adults, but common in the embryo
- principal component of the umbilical cord,called Whartons jelly
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DENSE CONNECTIVE TISSUE
Dense Irregular Connective Tissue
Dense Regular Connective Tissue
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DENSE IRREGULAR CONNECTIVE TISSUE
- collagen fibers
- free cells are very few
- found in the dermis of the skin; capsules ofthe spleen, liver, and lymph nodes; tunicaalbuginea of the testis; the dura mater of thebrain; and sheaths of large nerves
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DENSE REGULAR CONNECTIVE TISSUE
- flat sheets of closely approximated coarsecollagen fibers
- tendons
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HISTOPHYSIOLOGY OF CONNECTIVE TISSUE
NORMAL FUNCTIONS
MechanicalSUPPORT
EXCHANGEof metabolites
STORAGEof energy reserves in adiposecells
PROTECTIONagainst infection
REPAIRafter injury
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INFLAMMATION
- invasion of tissues by microorganismstriggers a local response of the connectivetissue
- redness, swelling and pain
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EFFECTS OF HORMONES
- influenced by sex hormones
Protein synthesis by fibroblasts aresuppressed
Permeability of capillaries is decreased
Lysosomal membranes of phagocytes arestabilized
Lymphocytes are destroyed
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REPAIR
- they not only heal defects in the connective
tissue but also respond to injury to othertissues that have little capacity for repair
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CONNECTIVE TISSUE DISEASE
1. Ehlers-Danlos Syndrome
2 Osteogenesis Imperfecta
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2. Osteogenesis Imperfecta
3 Lathyrism
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3. Lathyrism