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15 Cards in this Set
- Front
- Back
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Cartilage
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- flexible but strong
- chondrocytes in lacunae and ECM - characterized by ECM with GAGS (these are important because there is no circulatory system present) and proteoglycans interacting with collagen and elastin - firm consistency of ECM bears stress - 95% of cartilage is ECM - cartilage is avascular |
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Three Types of Cartilage
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1. Hyaline (most widespread)
- surrounded by perichondrium (outer layer) - ECM of type II collagen - Embryo, articular cartilage (where joints come together), respiratory tract 2. Elastic - hyaline + elastin - perichondrium is also present - external ear, epiglottis, auditory tube 3. Fibrocartilage (tougher) - lacks perichondrium - hyaline with type I collagen + dense CT - Intervertebral disks, disks of kneww, mandible |
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Hyaline distribution and function
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- articulating joint- creates a low-friction surface so joints move well
- also creates a fluid called Synovium Fluid |
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Hyaline Cartilage
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Three components:
1. matrix (the bulk) 2. perichondrium 3. chondrocytes |
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The Matrix of Hyaline
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Classes of Molecules:
1. Collagen (type II) - bulk of ECM - cartilage-specific collagen 2. Proteoglycan - three types of GAGs: A.) Hyaluronic acid B.) Chondrotin Sulfate C.) Keratin Sulfate 3. Noncollagenous proteins - the matrix is highly hydrated (60-80% of hyaline is water) - also very negatively charged |
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Matrix Repair in Hyaline
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- tolerance (very tough, but when it does get damaged it's hard to repair)
- Repair: Chondrocyte (produces matrix); ECM conduit - Repair Factors to keep in mind: avascularity; chondrocyte immobility; limited proliferation |
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Cartilage Repair
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- there is a balance between repairing cartilage and creating scar tissue (type I collagen)
- the repair pattern: start as fibroblasts, get the repair signal, and turn into chondrogenic layer (type II) - Improvements in repair: pericondrial grafts; cell transplant; artificial matrices; growth factor application |
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Perichondrium
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- present except in articulating cartilage
- its a dense CT rich in collagen type I - in charge of repair - there are two layers: A) Fibrous layer- more distal B) Chondrogenic layer- under fibrous layer; responsible for making new chondrocytes (so it is the part that grows) |
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Chondrocytes
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- produced in two ways: chondrogenic layer or division into isogenous groups
- synthesize ECM - isogenous groups- collection of cells all from a parental cell - diffusion - zonation - they have anaerobic respiration - start out spindle-shaped but become rounder as they mature |
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Articular Cartilage
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- no perichondrium
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Hyaline histogenesis
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- Histogenesis: Mesenchyme-> Chondroblasts (start producing ECM) --> Chondrocytes (are mature; surrounded by ECM)
-Growth: either Interstitial (isogenous groups are dividing) or Appositional (chondrogenic growth, aka surface growth) |
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Elastic Cartilage
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- hyaline cartilage + elastin fibers/sheets (allows more flexibility)
- perichondrium present - NO calcification with age |
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Fibrocartilage
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- intermediate with dense CT
- singular or isogenous cells: arranged in straight rows; separated by collagen fiber bundles - NO perichondrium |
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Intervertebral disk (an example of fibrocartilage)
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- Annulus fibrosus- the outer sheet-like layer
- Nucleus pulposus- inner layer (jutting out of this causes a slipped disk) |
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Calcification of Cartilage
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- hyaline cartilage is prone to calcification (calcium phosphate depositied in matrix)
- Three Normal Occurrences: A) articular cartilage in contact with bone tissue in growing and adult bone, not surface portion B) endochondrial ossification C) aging process - calcification decreases diffusion |
