connective tissue
DESCRIPTION
Connective tissue. Seema Zargar. Connective tissue. Most diverse and abundant tissue Main classes Connective tissue proper Cartilage Bone tissue Blood Characteristics Mesenchyme as their common tissue of origin ( mesenchyme derived from mesoderm) Varying degrees of vascularity - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/1.jpg)
Connective tissueSeema Zargar
![Page 2: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/2.jpg)
Most diverse and abundant tissue Main classes
◦ Connective tissue proper◦ Cartilage◦ Bone tissue◦ Blood
Characteristics◦ Mesenchyme as their common tissue of origin
(mesenchyme derived from mesoderm)◦ Varying degrees of vascularity◦ Nonliving extracellular matrix, consisting of
ground substance and fibers ◦ Cells are not as abundant nor as tightly packed
together as in epithelium
Connective tissue
![Page 3: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/3.jpg)
Enclose organs as a capsule and separate organs into layers. Areolar
Connect tissues to one another. Tendons and ligaments.
Support and movement. Bones.
Storage. Fat
Insulation. Fat.
Transport. Blood.
Protection. Bone, cells of the immune system.
Functions of connective tissue
![Page 4: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/4.jpg)
Ground substance – unstructured material that fills the space between cells
Fibers – collagen, elastic, or reticular
Cells – fibroblasts, chondroblasts, osteoblasts, hematopoietic stem cells, and others.
Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content.
Structural Elements of Connective Tissue
![Page 5: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/5.jpg)
Connective tissue can be classified into three
categories:
proper,
embryonic,
specialized
Classification of Connective tissue
![Page 6: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/6.jpg)
![Page 7: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/7.jpg)
Subclassifications of C.T(proper)
![Page 8: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/8.jpg)
Embryonic: Is further divided into mesenchyme and mucoid.
Specialized: Is further divided into bone, cartilage and blood.
Connective tissue proper: Is further divided into elastic tissue, reticular tissue, adipose tissue, areolar (loose tissue) and dense tissue.
Sub classifications of CT
![Page 9: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/9.jpg)
![Page 10: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/10.jpg)
![Page 11: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/11.jpg)
![Page 12: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/12.jpg)
![Page 13: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/13.jpg)
Elastic fibres
![Page 14: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/14.jpg)
Reticular connective tissue
![Page 15: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/15.jpg)
Embryonic connective tissue
![Page 16: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/16.jpg)
Specialized connective tissue
![Page 17: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/17.jpg)
Collagen fibres
![Page 18: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/18.jpg)
![Page 19: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/19.jpg)
![Page 20: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/20.jpg)
Collagen is rich in proline and glycine, both of which are important in the formation of the triple-stranded helix. Proline facilitates the formation of the helical conformation of each αchain because its ring structure causes “kinks”in the peptide chain. Glycine, the smallest amino acid, is found in every third position of the polypeptide chain. It fits into the restricted spaces where the three chains of the helix come together. The glycine residues are part of a repeating sequence, -Gly–X–Y–, where X is frequently proline and Y is often hydroxyproline(but can be hydroxylysine,).
Most of the α-chain can be regarded as a polytripeptide whose sequence can be represented as (–Gly–Pro–Hyp–)
Structure of collagen
![Page 21: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/21.jpg)
![Page 22: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/22.jpg)
![Page 23: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/23.jpg)
Collagen biosynthesisEndoplasmic Reticulum
mRNA attached to ERprotein synthesized into ER lumencotranslational and post-translational modifications3 proto-a-chains form soluble procollagenmoved to golgi apparatus
Golgi Apparatuspacked into secretion vesiclesfuse with membrane
Outside Cellprocollagen processed by enzymes outside cellassemble into collagen fiberscollagen fibrils form lateral Interactions of triple helices
![Page 24: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/24.jpg)
Collagen biosynthesis
![Page 25: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/25.jpg)
Tropocollagen as the basic structural unit of Collagen Tropocollagen has a mass of about 285 kdal and
consist of three polypeptide chains. Tropocollagen -280 nm long -head & tail region
30% glycine, 30% proline& hydroxyproline re-aggregate -native collagen (64nm)
non Covalent hydrogen bonding between the three αchain is via hydroxyproline.
tropocollagenpolarized in fiber, 1/4 staggered array –period accounted for by gaps fall in dark bands
![Page 26: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/26.jpg)
Staggered array of tropocollagen Molecules
Collagen fibres exhibit crosssstriations every 640A.
The length of the tropocollagenmolecule s 2800A.
There is a gap of 400oA between the end of one tropocollagenand the start of another. This gap play an important role in mineralization process.
![Page 27: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/27.jpg)
Tropocollagen structure
![Page 28: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/28.jpg)
Tropocollagen stabilization
![Page 29: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/29.jpg)
Lysyl oxidase is an extracellular copper enzyme that catalyzes formation of aldehydes from lysine residues in collagen and elastin precursors. These aldehydes are highly reactive, and undergo spontaneous chemical reactions with other lysyl oxidase-derived aldehyde residues, or with unmodified lysine residues. This results in cross-linking collagen and elastin, which is essential for stabilization of collagen fibrils and for the integrity and elasticity of mature elastin.
Complex cross-links are formed in collagen called Pyridinoline which is derived from three lysine residues.
![Page 30: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/30.jpg)
![Page 31: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/31.jpg)
Stability of the collagen helix™ The temperature at which half of the helical structure is lost
is called the melting temperature™.
The Tm of tropocollagenis a criterion of the stability of its helical structure. Tm depends on the body temperature of the source species. collagens from icefishhas the lowest Tm while warm blooded animals have the highest Tm. This difference in thermal stability is correlated with the contents of iminoacid (prolineand hydroxyproline) in the collagen. The higher the iminoacid content , the more stable the helix. Tm of (pro-pro-Gly) is 24C while poly (Pro-Hyp-Gly) is 580C indicating hydroxylation stabilizes triple helix.
The experiments using αα\-bipyridylan iron chelatorwhich inhibit hydroxylation shows that without hydroxylation triple helix formation does not occur.
![Page 32: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/32.jpg)
Collagenase and its types Source: Clostridium histolyticum
I.U.B.: 3.4.24.3 Crude collagenase preparations contain not only several
collagenases but also a sulfhydryl protease, clostripain, a trypsin-like enzyme, and an aminopeptidase. This combination of collagenolytic and proteolytic activities is effective at breaking down intercellular matrices, the essential part of tissue dissociation. One component of the complex is a hydrolytic enzyme which degrades the helical regions in native collagen preferentially at the Y-Gly bond in the sequence Pro-Y-Gly-Pro- where Y is most frequently a neutral amino acid. This cleavage yields products susceptible to further peptidase digestion. Crude collagenase is inhibited by metal chelating agents such as cysteine, EDTA or o-phenanthroline but not DFP. It is also inhibited by α2-macroglobulin, a large plasma glycoprotein. Ca2+ is required for enzyme activity. Particular enzymatic profiles of each collagenase have been correlated with the tissues from which the cells for study were obtained (or with the uses to which the cells are put) and as a result of the correlations several types of crude collagenases have been established by Worthington: Types 1, 2, 3, and 4.
![Page 33: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/33.jpg)
Type 1 crude collagenase has the original balance of collagenase, caseinase, clostripain and tryptic activities.
Type 2 contains higher relative levels of protease activity particularly clostripain.
Type 3 contains lowest levels of secondary proteases.
Type 4 is designed to be especially low in tryptic activity to limit damage to membrane proteins and receptors.
![Page 34: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/34.jpg)
Elastin composition
![Page 35: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/35.jpg)
Elastin Elastin is a protein in connective
tissue that is elastic and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of vertebrates and used in places where mechanical energy is required to be stored. In humans, elastin is encoded by the ELN gene.
![Page 36: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/36.jpg)
Composition of elastin Elastic fiber is composed of the
protein fibrillin and elastin made of simple amino acids such as glycine, valine, alanine, and proline.
Elastin is made by linking many soluble tropoelastin protein molecules, in a reaction catalyzed by lysyl oxidase, to make a massive insoluble, durable cross-linked array. The amino acid responsible for these cross-links is lysine. Tropoelastin is a specialized protein with a molecular weight of 64 to 66 kDa, and an irregular or random coil conformation made up of 830 amino acids.
Desmosine and isodesmosine are types of links for the tropoelastin molecules.
![Page 37: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/37.jpg)
Tissue distribution Elastin serves an important function in arteries as
a medium for pressure wave propagation to help blood flow and is particularly abundant in large elastic blood vessels such as the aorta.
Elastin is also very important in the lungs, elastic ligaments, the skin, and the bladder, elastic cartilage.
It is present in all vertebrates above the jawless
fish.
![Page 38: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/38.jpg)
Biosynthesis of elastin
![Page 39: Connective tissue](https://reader035.vdocument.in/reader035/viewer/2022062501/568164eb550346895dd7573c/html5/thumbnails/39.jpg)
Structure protein Mr 64 to 66 kDa composed of the amino acids glycine, valine,
alanine, and proline cross-linked tropoelastin monomers first secreted as soluble precursors (tropoelastin) assembly and crosslinking of tropoelastin
monomers form insoluble elastin matrix into functional fibres
◦ lysine residues in the cross-linking domain of secreted tropoelastin rapidly cross-linked (both inter- and intra-molecularly by lysyl oxidase)
◦ hydrophobic segments - elastic properties◦ α-helical segments (alanine- and lysine-rich) - form
cross-links between adjacent molecules