Connective TIssues Charecteristics

Question 1

Connective Tissue Charecteristics

Answer 1

• Connective tissue is what is left over after everything else(epithelia,muscle, and nervous tissue) is removed
• It is found in every organ system except the CNS
• Unlike epithelial tissues, connective tissue has relatively few cells
• Major charecteristic of connective tissue is an abundnat matrix
• connective tissue matrix contains varying amounts of protein fibers
• Connective tissue is typically classified on the basis of tye type of matrix,fiber denisty, and fiber organization

Question 2

Connective tissue Functions

Answer 2

• Connective tissue physically supports other tissues
• Connective tissue binds other tissues together
• Connective tissue provids strucutural framework and oppose gravity
• Connective tissue helps to create body counters
• Connective tissue house specialized tissues(i.e.):
  
  • Blood forming tissue(hematopoietic)
  • Lymphoid tissue

Question 3

Connective TIssue Classification

Answer 3

• Embryonic connecitieve tissue
• adult connective tissue:
  
  • Loose
    
    • Both collagen and elastic fibers are present and arranged in a very loose,random fashion
  • Dense
    
    • collagen fibers predominate
      
      • Dense regular
      • Dense irregular
  • Reticular
    
    • reticular fibers predominate
  • Elastic
    
    • Elastic fibers predominate
• Special

Question 4

Embryonic Connective Tissue

Answer 4

• Found in umbilical cord and in the pulp of developing teeth
• Referred to as “Wharton’s” jelly in umbilical cord
• Composed of some collagen and elastic fibers but mostly an abudnacne of extracellular matrix

Question 5

Adult connective tissue loose

Answer 5

• High ratio of fibroblasts to fibrous components
• Type I collage nfibers adn elastic fibers
• Usually found beneath epithelial tissues of most organs,including the tunica adventita of blood vessels
• Contains fibroblasts , mast cells,macrophages,and capillaries

Question 6

Adult connective tissue , Dense regular

Answer 6

• High ratio of fibrous components to fibroblasts
• thicker bundles of collagen than in loose connective tissue
• Dense regular connective tissue is charecterized by highly ordered bundles of collagen separated by single rows of fibroblasts
• found in tendons and ligaments

Question 7

Adult Connective Tissue Dense irregular

Answer 7

• High ratio of ibrous componets to fibroblasts
• Thicker bundles of collagen than in loose CT
• Dense irregular connective tissue has no specific orientation of collagen bundles
• Found in fascia, submucosa of GI tract, and in dermis of integument
• No parallel organization but still densely packed

Question 8

Reticular

Answer 8

• A type of dense irregular connective tissue with a predominance of reticular fibers
• Associated primarily with lympathic tissue

Question 9

Elastic

Answer 9

• A type of dense irregular connective tissue with an abudnane of elastic fibers which form discontinuous lamellae
• Associated with walls of blood vessels:
  
  • Note that elastic fibers in walls of blood vessels are produced by smooth muscle cells rather than fibroblasts

Question 10

Answer 10

Tendon and muscle

Question 11

Special types of connective tissue

Answer 11

• Adipose
• carilage
• bone
• Hematopoietic(blood forming tissue)
• Special becasue the protein fibers are not conspicous
• wouldn’t recognize it or know that it’s connective tissue
• Embryonic morphology also plays a part in classification

Question 12

Adipocytes

Answer 12

• Derived from undifferentiated mesenchymal cells and are distinguished by their unique apperance
• Most are about 150 micrometers in diameter
• Types:
  
  • White fat is distributed throughout the body:
    
    • unilocular-a single large fat inclusion, resulting from coalescing multiple lipid droplets , pushes the nucleus to an eccentric position
  • Brown fat cells contain numerous small lipid droplets:
    
    • Multiocular
    • Slighly more cytoplasm
    • Abundnat mitochondria , which give them their brown coloration

Question 13

Answer 13

Adipose tissue

Question 14

connective Tissue Matrix

Answer 14

• Connective tissue proper consists of cells scattered in a relatively homogeneous matrix
  
  • most common cells are fibrocytes and fibroblasts
• The matrix consists of protein fibers and ground substance
  
  • Most abundnat fibers are collagen fibers
  • other fiber tpes include reticular fibers and elastic fibers
  • ground substance is mostly composed of glycosaminoglycans and glycoproteins

Question 15

Collagen Fiber types

Answer 15

• Type1: General CT and bone
  
  • Function:tensile strength
• Type2: hyaline and elastic cartilage
  
  • Function:tensile strength
• Type3: Parenchyma of organs adn walls of blood vessels
  
  • Function:reticular framework
• type 4:Basment membranes
  
  • Function:meshwork,scaffolding

Question 16

Collagen fiber synthesis

Answer 16

Type I collage is synthesized as a prepropeptide

• Signal(pre-)sequence is cleave after translocation of the polypeptide into the endoplasmi reticulum(ER) lumen of the fibroblast
• After the singal sequence is cleaved , the propeptide(procollagen) molecule is secreted by the firoblast into the extracellular matrix
• Procolagen molecule has terminal non-helical ends that prevent polymerization
  
  • These non-helical ends are cleaved by petidases in order to allow polymerization to occur
  • After the terminal ends are cleaved , the molecuel is referred to as tropocollagen
• Tropocollagen monomers spontaneously assemble into staggered arrays to fomr collage fibers with characteristic 64nm banded pattern
• assembled polymer is collagen

Question 17

Elastic Fiber synthesis

Answer 17

• Elastin is also synthesized as a prepropeptide
• The prepropepide is secreted as a propeptide
• Propeptide is converted to tropelastin by extracellular enzymes , also secreted by the fibroblast
• Tropoelastin monomers are assembled into amorphous fibers or sheets with the aid of several types of fibrillins

Question 18

Glycosaminoglycans

Answer 18

• Glycosaminoglycans(GAGs) are large,negativlely cahrged linear polymers(polysaccharides) consisting of repeatd disaccharide units
  
  • GAGs were originally referred to as acid mucopolysacchardies
• Along with glycoproteins,GAGs form most of the amorphous substance of connective tissue
• All GAGs ,except hyaluronic acid , are covalently linked to protein to form proteoglycans

Question 19

Hyaluronic acid

Answer 19

• Largest of the GAGs
• Cartilage ,skin,synovial fluid,and general CT
• Only GAG which lacks sulfate groups
• Consists of repeating carbohydrate chains of N-acetylglucosamine and D-glucoronic acid
• Present in nearly all ocnnective tissues and in virteous body of eye, synovial fluid, and Wharton’s jelly
• Binds readily with water and serves as lubricant in synovial fluids

Question 20

Heparin and heparan sulfate

Answer 20

• Basement membrane ,skin, lung , liver,blood vessels, mast cell granules
• repeating unit is N-acetylglucosamine and D-glucuronic acid

Question 21

Chondroitin sulfate and dermatan sulfate:

Answer 21

• Cartilage ,bone ,skin,blood vessels , heart valves , cornea
• Most abundant of the sulfated GAGs
• Repeating unit in chondroitin sulfate is N-acetylglucosamine and D-glucuronic acid
• Repeating unit in dermatan sulfate is N-acetylglucosamine and iduronic acid
• Dermatan sulfate is dominant in the skin

Question 22

Keratan sulfate

Answer 22

• Type 1 found only in cornea
• Type II is found in cartilage and nucleus pulposus of intervertebral disks
• Repeating unit is N-acetylglucosamine and galactose

Question 23

Proteoglycans are extracellular protein complexes of glycosaminoglycans

Answer 23

• An axial hyaluronan molecule
• core proteins attached to the hyaluronan molecule by a linker protein
• Glycosaminoglycnas attached to a core protein
• Several chains of glycosaminoglycans bound to the core protein form a prtoeglycan

Question 24

Proteoglycans

Answer 24

• Secreted products of resident cells:
  
  • Fibroblasts,chondroblasts,osteoblasts,synovial cells, smooth muscle cells(all derived from the primitive mesenchyme)
• Polyanions
• Stain with convential dyes such as hematoxylin because of sulfate groups
• Toluidin blue and bystal violet are cationic dyes that are metachromatic when reacting with the anionic groups of the proteoglycans
• Proteoglycans are comperssible, will return to their original shape

Question 25

Glycoproteins

Answer 25

• Glycoproteins are proteins wiht one or more heterosaccharide chains containing hexosamine, glactose , and toher sugars
• Glycoproteins are PAS+
• Main charecteristics are high protein content and branched carbohydrate moieties
  *

Question 26

Fibronectin

Answer 26

• Example of glycoportein
• Major surface protein of fibroblasts
• Synthesized also by epithelia and endothelia
• Occurs in plasma(=cold insolutlbe globulin or plasma fibronectin)
• occurs in alpha granules of platelets
• links, cells,collagen and glycosaminoglycans

Question 27

Chondronectin and Laminin

Answer 27

• example of glycoproteins
• Chondronectin:
  
  • Isoalted from cartilage
  • Promotes adhesion of mature chondroctes to collagenous
• Laminin
  
  • Found in basal laminae(component of lamina rara)
  • Involved in the attachment of epithelial cells to the lamina propria
  • noncollagenous glycoprotein