101 Cartilage
Transcript of 101 Cartilage
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WHERE AM I? Online Anatomy Module 1
APPENDICULAR SKELETON
CELL
INTRO & TERMS
EPITHELIUM
CARTILAGE
MUSCLE
NERVOUS SYSTEM
AXIAL SKELETON
MUSCLES
EMBRYOLOGY
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SKELETON & DISTINCT CARTILAGE SKELETONS
Cartilage participates as pieces that
develop, and stay attached to the skeleton
Nasal cartilage
Xiphoid processan extension to
the breast-bone
Other cartilages act as separate skeletal
elements in their own right: supporting the
larynx (voice-box) [feel its firmness on
yourself] and the trachea (windpipe) & bronchi
Ear cartilage
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CARTILAGE & ITS SITES
Cartilage is a firm, but flexible,
pressure-resisting tissue,needed to support and connect
other tissues and structures
Ears
Nose
Airway
Spine disks
Joints
Ends of ribs
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CARTILAGES: Technical names
Auricular cartilageEars
Nose
Airway
Spine disks
Joints
Ends of ribs
Nasal/septal cartilage
Laryngeal & tracheal cartilages
Costal cartilages
Intervertebral disks
Articular cartilages
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CARTILAGE
Cartilage cells introduceto the tissue resistance to
pressure & an ability to recover shape , principally by
aggregated proteoglycans able avidly to bind water.
The PGs themselves are held in place by a meshwork
of fine collagen fibrils (tiny fibers).
Matrix ofChondrocytes make a
Collagen II fibrilmeshwork trapping aggregated ProteoglycansPGs
aggregating
backbone of
HYALURONAN
PG
L
L
L
L
H2OPGs bind
PG
L - Link protein
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CARTILAGE
Cartilage cells introduceto the tissue resistance to pressure & an ability
to recover shape, principally by aggregated proteoglycans able avidly to
bind water. The PGs themselves are held in place by a meshwork of fine
collagen fibrils.
Fibrocartilage is dense fibrous
tissue with chondrocytes & their
PGs substituted for fibroblasts
Intervertebral disk is under pressure, but has tensile strengthto resist bursting and pull
nucleus pulposus
fibrocartilage of
annulus fibrosus
vertebral endplate
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CARTILAGE
Fibrocartilage is dense fibrous tissue with
chondrocytes & their PGs substituted for fibroblasts
Intervertebral disk is under pressure, but has tensile strengthto resist bursting and pull
nucleus pulposus
fibrocartilage of
annulus fibrosusFibril orientation
differs from one
fibrous layer to
the next
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CARTILAGE
Intervertebral disk is under pressure, but usually hasenough tensile strength to resist bursting and pull, however
nucleus pulposus
Herniated/ruptured disk pressing
on nerve leaving spinal canal,e.g., causing sciatica
fibrocartilage of
annulus fibrosus
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Joint capsule
Bone
Muscle
JOINT/ARTICULAR CARTILAGEresilient, thin, lubricated,
attached, living, nourished,
modifiable,
vulnerable
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JOINT TERMS
loose connective tissue
lining cells
{
Spongy subchondral
bone absorbs and
directs load to shaft
Joint cartilage
absorbs and
spreads load
SYNOVIUM
Joint capsule
j c
o ai v
n i
t t
. y
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SKELETON & CARTILAGE
Facial and skull vault/dome bones form
with negligible cartilage present
Cartilage participates as pieces that
develop, and stay attached to the skeleton
Other cartilage develops with bones
(indeed, it precedes the bone), then
remains at the ends to make the joint
surface or articular cartilage
Cartilage provides some flexibility &
recovery of shape at critical places
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SKELETAL DEVELOPMENT
Skeletal piece of
hyaline cartilageGrows by internal expansion
and from the surface
Cell
enlargement/hypertrophyMatrix calcification
selective erosion into
mineralized cartilage
Calcified cartilage can be
resorbed like bone, and
be attached to bone
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Secondary ossificationcenters
Growth/epiphyseal plate
Articular cartilage
Shaft bonegrows bydeposition on the outside,
with mild resorption on the
inside surface, plus
osteonal remodellingin the
interior
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LATER ENDOCHONDRAL OSSIFICATION
Bone would belarger
thanin theprevious view
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JOINTCARTILAGE
layer ofmineralizedcartilage for
attachment to
Spongysubchondralbone
Matrix
Chondrocytes inholes/lacunae
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JOINT CARTILAGE
Matrix ofChondrocytes make a
Collagen II fibrilmeshwork trapping aggregated ProteoglycansPGs
aggregating
backbone of
HYALURONAN
PG
LL
L
L
H2OPGs bind
PG
L - Link
protein
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PROTEOGLYCAN STRUCTURE & H2O-BINDING
Core protein
Sugar side-chains of repeating
pairs (disaccharides)
-XL-GA-GU-GA-GU-GA-GU-GA-GU-SO4
coo
Side chains bear -binding charged groups
which mutually repel, but cannot disperse because
ofO2 bonds& anchorage to thecore protein
H2O
H2O
} SO4SO4
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Nutrition
SYNOVIAL FLUID
Lubrication
Nutrition from marrow blocked by mineralized-cartilage
Load-bearing surface, therefore
vessels would not survive
ARTICULAR CARTILAGE NUTRITION
Why via synovial fluid? #1
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JOINT/ARTICULAR CARTILAGE
Resilient - Meshwork loaded with H2O-trapping
huge molecules
Lubricated - Synovial fluid & its special molecules
Attached - Via mineralized lowest layer to
subchondral bone
Living - Matrix allows diffusion to chondrocytes inlacunae
Nourished - From synovial vessels via synovialfluid
Modifiable- Cells continue to make & selectivelydestroy ECM
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JOINT CARTILAGE VULNERABILITIES
Thin and easily worn away (osteoarthrosis)
Relies on very indirect nutrition
A few cells look after extensive matrix
Has nearby a loose CT (synovium) in whichdamaging defensive responses occur, e.g., to
crystals (gout), virus? (rheumatoid arthritis)
Inflammatory synovial cells release damaging
enzymes into synovial fluid, or cytokine signals
turning on chondrocyte ECM destruction
Large ECM molecules (PGs & Collagen) easily
cleaved by enzymes into useless shorter pieces
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HYALINE
CARTILAGE
Airway
skeletonTracheal rings
Laryngeal
pieces
Precursor to
bony skeleton
stays on as
Articular cartilage
like hyaline, but
reinforced with
elastic fibers Auricle(ear)
more like dense
fibrous tissue
CARTILAGE TYPES
ELASTIC
CARTILAGE
FIBROCARTILAGE
a few vocal Laryngeal pieces
joins bones, e.g., vertebrae,
& tendons to bone
CARTILAGES T h i l
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CARTILAGES: Technical names
Auricular cartilage elasticEars
Nose
Airway
Spine disks
Joints
Ends of ribs
Nasal/septal cartilage
Laryngeal & tracheal cartilages
Costal cartilages
Intervertebral disks
fibrocartilage
Articular cartilages
The rest are hyaline, as is most
of the embryonic skeleton
TYPICAL PIECE* OF CARTILAGE
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TYPICAL PIECE* OF CARTILAGE
PERICHONDRIUM ( dense irregular CT)
Chondrocytes
* Fibrocartilage does not occur as discrete pieces
vessels
CARTILAGE GROWTH
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PERICHONDRIUMAppositionalgrowth by
surface cell division &differentiation
Chondrocytes
Interstitialgrowth by interior
cell division & matrix depostion
Chondroblasts
CARTILAGE GROWTH
JOINT COMPONENTS
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JOINT CAPSULE
PeriosteumFibrous
Osteoblastic
Spongy bonewith struts/
trabeculae
Joint cartilage
absorbs and
spreads load
JOINT COMPONENTS
SYNOVIUM
LIGAMENT
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JOINT CAPSULE
JOINT CAPSULE & SYNOVIUM
SYNOVIUM
Synovium lines
the joint capsule,but it itself has a
lining or surface
JOINT SPACE
EASY SLIDING
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EASY SLIDING
FIRM ELASTIC SUBSTRATE
FIRM ELASTIC SUBSTRATE
BOUNDARY
LUBRICANT
FLUID FILM
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EASY SLIDING: Synovial Joint
orDisc
Attached, polar
PHOSPHOLIPID molecules
WATER +
HYALURONAN
+ PROTEINS
Articular layer
Hydrophilic side
attaches to cartilage
Hydrophobic side
lowers surface
energy for NON-
STICK surface
Bond toArticular layer
SYNOVIOCYTE ROLES
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SYNOVIOCYTE ROLES
FIBROBLAST
synthesizes hyaluronan& glycoproteins
MACROPHAGEphagocytoses debris
in the joint space
SUB-INTIMA for inflammatory defensive
responses
SYNOVIAL FLUID
ECM MOLECULAR INTERACTIONS P th l 2
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Unwanted degradation by bystander inclusion in
cytokine signaling pathways of defensive cells
M
Lymphocytes of inner jointsynovium
IL-1
Articular
chondrocytes
IL-1
Joint cartilage cells alsorespond to the signal:
enzymes enzyme
inhibitors proteoglycans
= an inappropriate response causing cartilage
matrix destruction - ARTHRITIS
ECM MOLECULAR INTERACTIONS - Pathology 2
JOINT PANNUS
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JOINT PANNUS
SYNOVIUM
Joint cartilage
PANNUS is a overgrowth ofinflamed synovium onto & eating
into the articular cartilage
PTERYGIUM is a similar, but less inflamed
growth of conjunctiva onto the eyes cornea
SKELETAL DEVELOPMENT
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SKELETAL DEVELOPMENT
Skeletal piece of
hyaline cartilageGrows by internal expansion
and from the surface
Cell
enlargement/hypertrophyMatrix calcification
selective erosion into
mineralized cartilage
Calcified cartilage can be
resorbed like bone, and
be attached to bone
EARLY ENDOCHONDRAL OSSIFICATION
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EARLY ENDOCHONDRAL OSSIFICATION
EPIPHYSIS
}
}DIAPHYSIS/SHAFTprimary ossification
front
perichondrium
periosteum
Bony collar
provides support
as mineralized
cartilage is eatenaway
LATER ENDOCHONDRAL OSSIFICATION
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Secondary ossificationcenters
Growth/epiphyseal plate
Articular cartilage
Shaft bonegrows bydeposition on the outside,
with mild resorption on the
inside surface, plus
osteonal remodellingin the
interior
+-
LATER ENDOCHONDRAL OSSIFICATION
Bone would belarger
thanin theprevious view
ZONES/LAYERS OF THE GROWTH PLATE
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ZONES/LAYERS OF THE GROWTH PLATE
}
}}}
RESTING
PROLIFERATION
HYPERYTROPHY
CALCIFICATION
}OSSIFICATION
Expansion
Osteoclasts stop the
trabeculae from forever
extending
Matching erosion
new boneoncalcified cartila e
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Cartilage is replaced by bone. There is
no transformation of cartilage into bone
WHERE AM I?
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WHERE AM I? Online Anatomy Module 1
APPENDICULAR SKELETON
CELL
ORIENTATION
EPITHELIUM
CARTILAGE
MUSCLE
NERVOUS SYSTEM
AXIAL SKELETON
MUSCLES
EMBRYOLOGY
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