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34 Cards in this Set
- Front
- Back
Functions of conective tissue
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Mechanical (supporting matrix, force transmitter ie. tendons)
Metabolic (route of exchange between blood and tissues, fat storage) defence and repair (Fat - cushioning ie. heel, macrophages and mast cells involved in inflamm) Growth and morphogenesis (plays an important in development and maintainance of all tissues |
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ECM make-up
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Cells
Ground substance (anything non-cellular) |
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Define:connective tissues
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Any tissue where ground substance makes up more quantity than cellular material.
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Cells of connective tissue
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1.Mast cells
2.Macrophages - phagocytose invading organisms and dead cells. Also release local anti-inflammatories (cytokines) to keep inflamation local and prevent spread. 3.Fibroblasts - secrete matrix and growth factors 4.Leukocytes |
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Matrix/ground substance contents
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Glycosaminoglycans
Proteoglycans Glycoproteins |
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Glycosaminoglycans
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(ie. hyaluronic acid) long linear carbohydrates - extended conformation and occupy large volumes relative to their mass.
High negative charge - therefore attract a lot of water and form hydrated gels - contributes to viscosity and compressive pressure absorbing qualities of connective tissue. Pore size of the gels determined by GAGs present - therefore selective diffusion. |
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Proteoglycans
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Formed by cov linkage of GAGs to a core protein or glycoprotein.
Apart from structural role - also has role in activating and regulating the function of signalling molecules ie. FGF - activated by binding to a proteoglycan |
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Glycoproteins
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Smaller proteins that have been glycosylated ie.laminin. Provide a means by which cells can attach to, and move through, a matrix.
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Fibres of Connective tissue
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Mainly collagen - bone cartilage, clood vessels heart valves etc.
Type 1, 2 (cartilage) and 3 very similar - 3 helices wrapped around one another in superhelix. Type 4 in basal lamina forms sheets. Fibrillar collagen - 1 in 3 reesidues = glycine - critical to triple helix formation. |
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Osteogenesis imperfecta
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Brittle bone disease
One Glycine point mutation switches Unable therefore to form triple helix structur - vital to fibrillar shape and function. |
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Marfans
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Mutation of fibrillin - a component of elastic fibre - loss of integrity of fibres - tendency of aorta to rupture
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Scurvy
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Hydroylation of Pro residues in collagen important to form tight links between the strands - Vit C required
If no Vit C - reduced linking - fragility of skin, blood vessels and tendons - and loose teeth |
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Atherosclerosis
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Elastic fibres of blood vessel lost and replaced with collagen - tendency to dilate and possibly rupture
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3 types of cartilage
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Hyaline (template of bones, joints articular surface)
Fibro (intravertebral discs - type 1 collagen too) Elastic (external ear) |
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Appositional growth
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New cartilage added to surface of older cartilage by Chondroblasts from deep layer of perichondrium
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Interstitial growth
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Newer cartilage formed within older cartilage by chondrocytes that divide (and also produce new matrix)
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Bone - with epiphyseal plate - on which side does new cartilage form on - which side does it become bone?
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Ok this is end of bone (_) underscore is growth plate - new cartilage formed on top side, cartilage becomes bone on bottom side!
Resting zone Proliferative zone Hypertrophic zone Ossification zone |
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Bone - functions
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Calcium and phosphate reserve
Support Mobility Protection Bone marrow |
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Intramembranous ossification
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(Clavicle, skull)
Osteogenic progenitor cells differentiate in mesenchyme to form osteoblasts - secrete matrix. Some become embedded and become osteocytes. Differentiation into osteoblasts - initial formation of bone spicule Spicules enlarge and invaded by blood vessels Fusion of spicules to form plates of bone Start of osteoclastic remodelling |
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Osteoarthritis
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Breakdown of articular cartilage
Breakdown products can also cause local inflamm at the joint. |
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Cells of cartilage
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Chondroblasts (stem cells) secrete ECM of fibres and glycoproteins giving appositional (layer upon layer) and interstitial (internal) growth.
Mature Chondroblasts = chondrocytes - become embedded in lacunae |
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Osteoblasts, clasts and cytes
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Blasts - secrete matrix molecules, therefore form new bone.
Clasts - breakdown bone for remodelling by acid and proteolytic enzyme secretion. Cytes - embedded in bone - respond mechanical and other stimuli to initiate other events leading to new bone formation. |
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Perichondrium
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Layer of dense irregular connective tissue.
Outer layer contains fibroblasts secreting collagen fibres Inner layer containing undifferentiated stem cells, which can become Chondroblasts (which then become -cytes when embedded in lacunae) or Chondrocytes. Becomes the periosteum |
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Periosteum
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Outer fibrous layer
Innerlayer is osteogenic - can differentiate into Osteoblasts. |
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Endochondral ossification.
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see notes
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Collagen contributes...
Hydroxyapatite contributes.... |
Collagen - tensile strength E=denature - brittle
Hydroxyapatite - compressive E=demineralised - can fold around! |
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Neutrophils
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55%
Granulocyte Multi-lobed nucleus Small granules Phagocytose bacteria and fungi |
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Eosinophils
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5%
Granulocyte Bi-lobed nucleus Large Pink granules Kill metazoal parasites |
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Basophils
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1%
Granulocyte Large Blue granules Release histamine Bilobed nucleus |
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Monocytes
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5%
Agranular Kidney shaped nucleus Develop into macrophages which ; phagocytose and kills organisms Removes tissue debris Remodels tissue |
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Small lymphocyte
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30%
Round nucleus - clumped chromatin Quiescent, not dividing, awaiting activation by antigen Circulates blood looking for antigen, when finds-initiates immune response. |
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Large lymphocyte
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1-5%
bit bigger (12-16um) Kidney shaped nucleus Activated, dividing, developing to effector cells |
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Cytokines
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Intercellular communicating molecules
Interleukins are a sub division of these |
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Innate and adaptive response
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Innate - everything except lymphocytes - not more effective after previous infection
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