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15 Cards in this Set

  • Front
  • Back
Cartilage
- 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
Three Types of Cartilage
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
Hyaline distribution and function
- articulating joint- creates a low-friction surface so joints move well
- also creates a fluid called Synovium Fluid
Hyaline Cartilage
Three components:
1. matrix (the bulk)
2. perichondrium
3. chondrocytes
The Matrix of Hyaline
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
Matrix Repair in Hyaline
- 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
Cartilage Repair
- 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
Perichondrium
- 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)
Chondrocytes
- 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
Articular Cartilage
- no perichondrium
Hyaline histogenesis
- 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)
Elastic Cartilage
- hyaline cartilage + elastin fibers/sheets (allows more flexibility)
- perichondrium present
- NO calcification with age
Fibrocartilage
- intermediate with dense CT
- singular or isogenous cells: arranged in straight rows; separated by collagen fiber bundles
- NO perichondrium
Intervertebral disk (an example of fibrocartilage)
- Annulus fibrosus- the outer sheet-like layer

- Nucleus pulposus- inner layer (jutting out of this causes a slipped disk)
Calcification of Cartilage
- 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