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Semester 2 FS Exam 2 > Cartilage > Flashcards

Cartilage Flashcards

1
Q

Cartilage types

A

Articular
Fibrocartilage
Elastic

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2
Q

Articular

A

Hyaline
Most predominent in the body
Diarthrodial joints, growth plates

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3
Q

Fibrocartialge

A

Intervertebral disks, mandibular condyles, mensicus

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4
Q

Elastic cartilage

A

Epiglottis, eustachian tube

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5
Q

Composition of cartilage

A

water = 65-85%
Collagen - 75%
Proteoglycan 20-25%

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6
Q

Function of hyaline

A

covers boen surfaces within joint capsule
Fluid filled, water resistant boen surface
- Supports/tansmits laods across mobile surfaces
- Distributes joint loads over a wider area (stress reduction)
- Stabilizes and guides joint motion
- Lines ends of bones 9prevent wear)
- Lubrication reduces friction coef (.0025)

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7
Q

Composition of hyaline

A

Water
Chondrocytes (1%)
Organic matrix - collagen and proteoglycans and GAGS

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8
Q

Chondrocytes in hyaline

A

Produce collagen and proteoglycan as needed
Release enzymes to breakdown aging components
Building and rebuilding - very low amount so low ability to regenerate

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9
Q

Collagen orientation -hyaline

A

Parallel to the surface on the superficial layer
Oblique in the middle layer
Perpendicular to the surface in teh deep zone

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10
Q

Proteoglycan content - hyaline

A

Increases from the sruface to the middle zone and diminishes towards the deep zone

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11
Q

Superficial zone of hyaline

A

densely packed collagen fibrils
Organized in parallel to articular surface
Onlong chondrocytes

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12
Q

Middle zone of hyaline

A

Fibers more or less randomly arranged
Greater fiber diamtere
Round chondrocytes

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13
Q

Deep zone hyaline

A

Cells arranged in columns along the radial direction

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14
Q

Calcified cartilage and subchondral bone - hyaline

A

large fibers from the deep zone anchor into this region

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15
Q

Proteoglycan + collagen (hyaline0

A

Form structural networks of significant strength and are the strucutural components that support the internal mechanical stressed that result from external loads

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16
Q

Collagen in cartilage

A

Creates framework that houses the other components of cartilate
Majority is type II
Provides cartialge with tensile strength

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17
Q

Proteoglycans of cartilage

A

Each subunit consists of a combination of protein and sugar - long protein chain
Sugar units attached densley in parallel
Subunits are attached at right angles to a long filament
Produce macromolecules - proteoglycan aggregate

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18
Q

Tissues with high proteoglycan content

A

High water content
Low hydraulic permeability (doesnt allow water in/out)
Can tolerate high comp stress
Damage to proteoglycans will result in inc water mobility and impaired mechanical function

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19
Q

Structure of water - hyaline

A

Proteoglycans can hold up to water 50 times their weight
70% of water is bound to proteo
Remaining 30% is bound to collagen
Inorganic ions (Ca, Na, Cl, K) are dissolved - balance the fixed changes on proteo and generate swelling pressure

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20
Q

Swelling pressure

A
  1. Each sugar has 1/2 neg charges so they repel within subunit and among neighbors
  2. Causes molecule to extend stiffly out in space
  3. Proteoglycan requires a mobile counter ion (Na+) to maintain electroneutrality
  4. Neg charges make molecules hydrophilic and cause water to be trapped within
  5. Gives articular carticlae resis to compression
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21
Q

Interaction btw chemical and mechanical factors

A

High conc of GAGS in solution at physiological pH
High conc of fixed neg charges that create strong intra and inter molecular repulsive forces
This froces tends to extend and stiffen PGs
Osmosis requires discharge or attraction of counter ions for electroneutrality

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22
Q

Mechanical Bx results in

A

swelling pressure
Develops tension on collagen network even in absence of external load
Ext load –> deformation –> internal press inc –> liquid tendsd to flow out of the tissue
PG conc inc –> osmotic swelling pressure inc and resistance to compression is achieved

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23
Q

Anisotropic

A

Due to inhomogenous distribution of collagen and PGs

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24
Q

Toe region

A

Collagen fibrils straighten out and un-crimp (look wavy)

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25
Q

Linear region

A

Parallels the tensile strength of collagen fibirls: collagen aligns with axis of tension
Proportional

26
Q

Failure region

A

ruptures start to occur

27
Q

Under tension cartilage…

A

collagen fibers will stretch along the axis of loading

28
Q

Tensile loading is generated by the

A

intrinsic stiffness of collagen fibers

29
Q

Tensile stiffness is a measure of

Depends on…

A 
resistance to tensile loading
Depends on: 
1. density of collagen fibers
2. orientation of collagen fibers
3. type or amount of collagen cross linking
30
Q 
Tensile modulus (stiffness) varies from
Depending on...
A

5-25 MPa depending on:

  1. Location of joint surface (high or low weight bearing region)
  2. Depth of specimen
  3. Orientation of specimen relative to the joint surface
31
Q

Articular cartilage shows what kind of dependence

A

nonlinear strain and pressure dependence
The dec of permeability with compression acts to retard rapid loss of tissue fluid during high joint loadings (the less will be leaking out - less permeable)

32
Q

The more the tissue is squeezed (compressive strain)…

A

the less ability for water to move in and out - less permeability

33
Q

Cartilage under compression - load distribution, recovery due to unloading, and transport of large solutes depends on

A

Exudation (water out)
Inbibition (charges, bring in)
Flow of interstitial fluid (within the tissue)

34
Q

Cartilage under compression - The low permeability creates

A

energy dissipation through
High fluid pressure
Very high drag forces btw fluid and solid matrix
mechanism of protection of cartilage solid matrix from stresses and strains associated with normal joint load

35
Q

Cartilage under shear

The response to shear force is

A 
both stretching and deforamtion of solid matrix
Deformation without:
Change in volume
No pressure gradient
No fluid flow through the matrix
36
Q

Viscoelastic bx in shear is a result of

A

frictional interactions btw macromolecules
Collagen resists deformations in shear
Proteo contribute in generating a swelling pressure and that permits the matrix to more effectively resist shear

37
Q

Swelling pressure

A

balanced by stresses generated within the collagen ptoeoglycan solid matrix and stresses from joint loading - at equilibrium unloaded cartialge is in state of pre stress

38
Q

Permeability effects are recorded by

A

means of tissue weight change
less than 3% weight change in healthy human cartilage
greater than 30% in degenerate cartilage - OA = larger water permeability - not good

39
Q

Viscoeleasticity cartilage

A

Time dep response of a tissue subjected to a constant load or a constant deformation
Creep and stress relaxation

40
Q

The viscoelastic bx of cartialge is caused by

A

Interstitial flow
Macromolecular motion
Intrinsic viscoelastic bbehavior of collagen cell

41
Q

creep test

A

load is maintain constant
creep is controlled by exudation of fluid through porous platen
movement of fluid controlled by hydraulic permeability
equilibrium deformation controlled by intrinsic compressive modulus of specimen

42
Q

Rate of creep is determined y

A

rate at which fluid may be forced out of the tissue

This is governed by the permeablity and stiffness of porous permeable collagen - proteoglycan matrix

43
Q

For 2-4 mm human or bonvine AC takes ___ to reach creep equilibrium

A

4 to 16 hours

44
Q

Stress relaxation

A

squeeze it gradually and then maintain that ]

overtime stress will normalize and be maintained across

45
Q

The rate of loading is high…

A

the stiffer the tissue, the more stress it can take

46
Q

The lower the loading rate

A

the less stiff and the less stress it can take before getting damaged

47
Q

the lower the coefficient of friction…

A

the lower the friction

synovial fluid - allows for lower coefficient

48
Q

Meniscus

A

Semi lunare shaped fibrocartilaginous tissue
maintain the joint in approp position
Reduces stress concentration by extending contact area

49
Q

Surface layer of meniscus

A

fibers randomly distributed

50
Q

Deep layer of meniscus

A

most fibers circumferential

51
Q

Directional variation - split line pattern

A

indicates line of tension

52
Q

Directional variation - topographic variation

A

knee = 1-6mm thick

53
Q

Directional variation

A

Directional variation of the split line pattern is related to the tensile stiffness and strength characteristics of the tissue

54
Q

Intervertebral disk

A

can handle tension and compression and torsion and bending all at the same time

55
Q

Components of intervertebral disk

A

Outer annulus fibrosus
Inner nucleus pulposus
Cartilaginous end plates

56
Q

AF consists of

A

outer rim mainly type 1 collagen
fibrocartilage
transitional zone
Collagen fibers of AF are arranged in concentric cylindrical lamellae - collagen orientaion alternates btw adjacent lamellae

57
Q

Towards the center of ID

A

gradual reductin in collagen concentration
Collagen orientation becomes more random
Inc in proteoglycan content
Inc in water content

58
Q

NP consists of

A

randomly oriented colalgen

proteoglycans

59
Q

OA

A

imbalance of cartilage metabolism with OA - normal balance is disrupted

60
Q

Tensile and compressive moduli of cartilage ___ with OA severity

A

descreases
Tensile and compressive stiffness decreases
Fracture stress is also decreased

Semester 2 FS Exam 2 (6 decks)

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