CartilageCartilage

BoneBone

PRINCIPAL FUNCTIONS OF PRINCIPAL FUNCTIONS OF CARTILAGECARTILAGE

supporting soft tissuessupporting soft tissues

covering the surfaces of bones covering the surfaces of bones

forming the bone joints forming the bone joints

(shock absorber and sliding area)(shock absorber and sliding area)

development and growth of long development and growth of long

bonesbones

Chondrocytes Chondrocytes

Extracellular matrixExtracellular matrix

GROUND SUBSTANCE GROUND SUBSTANCE

Glicosaminoglicans Glicosaminoglicans

(GAG)(GAG)

Proteoglicans Proteoglicans

hyaluronic acidhyaluronic acid

FIBERSFIBERS

collagen collagen

fibersfibers

elastic fiberselastic fibers

PERICHONDRIUMPERICHONDRIUMThe capsule of connective tissue covering The capsule of connective tissue covering

the cartilagethe cartilage

outer layerouter layer - dense connective tissue - dense connective tissue

collagen type I collagen type I

fibroblastsfibroblasts

the source of nutrients for avascular the source of nutrients for avascular cartilagecartilage

inner layerinner layer

chondroblasts - precursors of chondrocyteschondroblasts - precursors of chondrocytes

TYPES OF CARTILAGETYPES OF CARTILAGEHyaline cartilageHyaline cartilage

the most common formthe most common form

contains mainly collagen type II fiberscontains mainly collagen type II fibers

Elastic cartilageElastic cartilage

many elastic fibers near the collagen type IImany elastic fibers near the collagen type II

more pliable than hyaline cartilagemore pliable than hyaline cartilage

FibrocartilageFibrocartilage

dense network type I collagen fibersdense network type I collagen fibers

present in regions subject to great mechanical present in regions subject to great mechanical stressstress

HYALINE CARTILAGEHYALINE CARTILAGE

articular surfaces of bones forming articular surfaces of bones forming movable jointsmovable jointsthe walls of big respiratory passages the walls of big respiratory passages

larynx, trachea, bigger bronchilarynx, trachea, bigger bronchiepiphyseal plates of long bonesepiphyseal plates of long bonesthe cartilaginous parts of ribsthe cartilaginous parts of ribs

covered by perichondrium covered by perichondrium (except articular cartilage)(except articular cartilage)

HYALINE CARTILAGE HYALINE CARTILAGE CHONDROCYTESCHONDROCYTES

develop from chondroblasts - cells present in develop from chondroblasts - cells present in the inner layer of the perichondriumthe inner layer of the perichondriumat the periphery - elliptic shapeat the periphery - elliptic shapefarther in - become round , form isogenous farther in - become round , form isogenous groupsgroupsisogenous group - develops by mitosis of isogenous group - develops by mitosis of single chondrocyte (5-8 cells in group)single chondrocyte (5-8 cells in group)produce all components of extracellular matrix produce all components of extracellular matrix

well developed RER, Golgi complexwell developed RER, Golgi complex

HYALINE CARTILAGE HYALINE CARTILAGE EXTRACELLULAR MATRIXEXTRACELLULAR MATRIX

collagen type II fibrils embedded in ground collagen type II fibrils embedded in ground substance substance

ground substance :ground substance :

proteoglicans proteoglicans

chondroitin sulfate, keratan sulfatechondroitin sulfate, keratan sulfate

long chains of hyaluronic acidlong chains of hyaluronic acid

chondronectin - glycoprotein providing chondronectin - glycoprotein providing adherence of collagen and chondrocytesadherence of collagen and chondrocytes

water bound to the negative charges of water bound to the negative charges of glicosaminoglicansglicosaminoglicans

Territorial matrixTerritorial matrix

surrounds each chondrocyte of isogenous surrounds each chondrocyte of isogenous groupgroup

rich in proteoglicans poor in collagen fibrilsrich in proteoglicans poor in collagen fibrils

Interterritorial matrixInterterritorial matrix

occurs between isogenous groupsoccurs between isogenous groups

numerous collagen type II fibrilsnumerous collagen type II fibrils

CharacteristicsCharacteristics

firm, resistant to compressionfirm, resistant to compression

ELASTIC CARTILAGEELASTIC CARTILAGE

auricle of the earauricle of the ear

the wall of external auditory canalsthe wall of external auditory canals

auditory tubes (Eustachian tubes )auditory tubes (Eustachian tubes )

epiglottisepiglottis

Presence of perichondriumPresence of perichondrium

ELASTIC CARTILAGEELASTIC CARTILAGEChondrocytes Chondrocytes

similar to cells of hyaline cartilage similar to cells of hyaline cartilage

smaller isogenous groups ( 2- 3 cells)smaller isogenous groups ( 2- 3 cells)

Extracellular matrixExtracellular matrix

abundant network of elastic fibers abundant network of elastic fibers

collagen type II fibrilscollagen type II fibrils

ground substance : the same components ground substance : the same components like in hyaline cartilagelike in hyaline cartilage

FIBROCARTILAGEFIBROCARTILAGE

annulus fibrosus of intervertebral discannulus fibrosus of intervertebral disc

symphysis pubissymphysis pubis

attachments of ligamentsattachments of ligaments

Great resistance to extentionGreat resistance to extention

FIBROCARTILAGEFIBROCARTILAGEChondrocytesChondrocytes

identical to cells of hyaline cartilageidentical to cells of hyaline cartilage

single or in groupssingle or in groups

groups - long raws of chondrocytesgroups - long raws of chondrocytes

Extracellular matrixExtracellular matrix

ground substance - less abundantground substance - less abundant

numerous collagen type I fibers - bundlesnumerous collagen type I fibers - bundles

collagen bundles: collagen bundles:

parallel to raws of cellsparallel to raws of cells

visible in light microscope visible in light microscope

BONEBONESpecific type of connective tissue with Specific type of connective tissue with

calcified extracellular substancecalcified extracellular substance

FunctionsFunctionssupporting soft tissuessupporting soft tissuesprotection of important organsprotection of important organs

CNS in skullCNS in skull thoracic contents in chest thoracic contents in chest

reservoir of calciumreservoir of calcium

OSTEOBLASTSOSTEOBLASTSform a layer which resembles the simple form a layer which resembles the simple epithelium on the surface of boneepithelium on the surface of bone

surround themselves with matrix and become surround themselves with matrix and become ostecytesostecytes

basophilic cytoplasmbasophilic cytoplasm

abundant RER, well developed Golgi complexabundant RER, well developed Golgi complex

Functions:Functions:

synthesize the organic components of matrixsynthesize the organic components of matrix

responsible for calcification of bone matrixresponsible for calcification of bone matrix

play certain role in bone resorptionplay certain role in bone resorption

OSTEOCYTESOSTEOCYTES

develop from osteoblasts which surrounded develop from osteoblasts which surrounded themselves with matrixthemselves with matrix

are located in matrix lacunae are located in matrix lacunae

(one cell per lacuna)(one cell per lacuna)

contact to each other by mean of cytoplasmic contact to each other by mean of cytoplasmic processes existing in canaliculi of matrix processes existing in canaliculi of matrix

surrounded by thin layer of noncalcified matrixsurrounded by thin layer of noncalcified matrix

less RER, smaller Golgi complex condensed less RER, smaller Golgi complex condensed nuclear chromatinnuclear chromatin

Function:Function: maintenance of the matrix maintenance of the matrix

OSTEOBLASTSOSTEOBLASTS OSTEOCYTESOSTEOCYTES

OSTEOCLASTSOSTEOCLASTSlarge, multinuclear cellslarge, multinuclear cellsderive from monocytes derive from monocytes (belong to phagocyte (belong to phagocyte system)system)ruffled border - surface facing ruffled border - surface facing bone ruffledbone ruffledclear zone - adhesion the cell to clear zone - adhesion the cell to the matrixthe matrixacidophilc cytoplasm acidophilc cytoplasm abundant RER and Golgi abundant RER and Golgi complex numerous complex numerous mitochondria and lisosomesmitochondria and lisosomes

Functions:Functions: bone resorption bone resorption bone growth and bone bone growth and bone

remodelingremodeling repair of fracturesrepair of fractures

OSTEOCLASTSOSTEOCLASTS

BONE BONE EXTRACELLULAR MATRIXEXTRACELLULAR MATRIX

Organic componentsOrganic components ( 30-35% of bone weight) ( 30-35% of bone weight)

collagen type I fibers ( 90%)collagen type I fibers ( 90%)

noncollagenous proteins : noncollagenous proteins :

osteonectin, osteocalcin, sialoproteins, osteonectin, osteocalcin, sialoproteins, phosphoproteins, proteolipidsphosphoproteins, proteolipids

proteoglicansproteoglicans

Inorganic componentsInorganic components ( 70% of bone weight) ( 70% of bone weight) calcium phosphate - hydroxyapatyte crystalscalcium phosphate - hydroxyapatyte crystals

PeriosteumPeriosteumLayer of connective tissue covering the boneLayer of connective tissue covering the bone

Outer layerOuter layer - - dense connective tissue dense connective tissue

fibroblastsfibroblasts

numerous collagen fibersnumerous collagen fibers

rich in blood vessels rich in blood vessels (source of vessels for bone)(source of vessels for bone)

Inner layerInner layer

osteoprogenitor cells osteoprogenitor cells (reservoir of osteoblasts)(reservoir of osteoblasts)

EndosteumEndosteum

Thin layer of connective tissue with Thin layer of connective tissue with osteoprogenitor cellsosteoprogenitor cells

Lines internal surfaces of the boneLines internal surfaces of the bone

Types of boneTypes of bone

IMMATURE BONEIMMATURE BONE = = PRIMARY BONEPRIMARY BONE = = = woven bone= woven bone

MATURE BONEMATURE BONE = = SECUNDARY BONESECUNDARY BONE = =

= = lamellar bonelamellar bone Compact boneCompact bone Cancellous bone = spongy boneCancellous bone = spongy bone

SECUNDARY BONE SECUNDARY BONE MATURE BONEMATURE BONE

Present in adultsPresent in adultsCharacteristicsCharacteristics

smaller number of osteocytessmaller number of osteocytesbone matrixbone matrix

abundant, well calcified abundant, well calcified arranged in lamellae arranged in lamellae regular arrangement of collagen fibersregular arrangement of collagen fibers lamellae form osteons (Haversian systems)lamellae form osteons (Haversian systems)

great resistance to mechanical forcesgreat resistance to mechanical forces

SECUNDARY BONE SECUNDARY BONE MATURE BONEMATURE BONE

EndosteumEndosteum

Thin layer of connective tissue with Thin layer of connective tissue with osteoprogenitor cellsosteoprogenitor cells

Lines internal surfaces of the boneLines internal surfaces of the bone

PRIMARY BONE PRIMARY BONE IMMATURE BONEIMMATURE BONE

formed in embryo during bone formationformed in embryo during bone formation

develops in repair process after fracturedevelops in repair process after fracture

replaced by mature bonereplaced by mature bone

irregular array of collagen fibrils in the organic irregular array of collagen fibrils in the organic part of matrixpart of matrix

smaller calcificationsmaller calcification

many osteocytes, little of bone matrixmany osteocytes, little of bone matrix

smaller mechanical resistancesmaller mechanical resistance

HISTOGENESISHISTOGENESIS

Intramembranous ossificationIntramembranous ossification

on the ground of mesenchymal tissueon the ground of mesenchymal tissue

formation of flat bones formation of flat bones

e.g. bones of the skulle.g. bones of the skull

Endochondral ossificationEndochondral ossification

on the ground of cartilaginous model on the ground of cartilaginous model of the boneof the bone

formation of long bonesformation of long bones

INTRAMEMBRANOUS INTRAMEMBRANOUS OSSIFICATIONOSSIFICATION

1. penetration of blood vessels into 1. penetration of blood vessels into mesenchymal tissuemesenchymal tissue

2. mesenchymal cells differentiate into 2. mesenchymal cells differentiate into osteoblastsosteoblasts

3. formation of bone spicules3. formation of bone spicules

ENDOCHONDRAL ENDOCHONDRAL OSSIFICATION OSSIFICATION

1.1.

formation of bone collar within an formation of bone collar within an inner layer of perichondrium of the inner layer of perichondrium of the diaphysisdiaphysis

(intramembranous(intramembranous ossification)ossification)

ENDOCHONDRAL OSSIFICATION

2. 2.

hypertrophy of chondrocyteshypertrophy of chondrocytes

deposition of calcium salts in the deposition of calcium salts in the cartilage matrixcartilage matrix

degeneration of chondrocytes degeneration of chondrocytes

ENDOCHONDRAL ENDOCHONDRAL OSSIFICATIONOSSIFICATION

3. 3.

penetration of osteogenic bud across penetration of osteogenic bud across bone collar into degenerated cartilagebone collar into degenerated cartilage

ENDOCHONDRAL ENDOCHONDRAL OSSIFICATIONOSSIFICATION

4. 4.

phagocytes resorb the cartilagephagocytes resorb the cartilage

osteoblasts start the production of osteoblasts start the production of bone matrix on the remnants of bone matrix on the remnants of cartilagecartilage

PRIMARY OSSIFICATION CENTERPRIMARY OSSIFICATION CENTER

BONE GROWTHBONE GROWTHFLAT BONESFLAT BONES

1. Formation of bone on the external surface 1. Formation of bone on the external surface

osteoprogenitor cells of periosteum osteoprogenitor cells of periosteum (intramembranous ossification)(intramembranous ossification)

2. Resorption of bone on the internal surface2. Resorption of bone on the internal surface

osteoclastsosteoclasts

BONE GROWTH BONE GROWTH LONG BONESLONG BONES

epiphyses - radial growth of cartilage epiphyses - radial growth of cartilage cartilage is gradually replaced by bone cartilage is gradually replaced by bone

the diaphysis increases in width by the diaphysis increases in width by formation of bone by periosteum on the formation of bone by periosteum on the external surfaceexternal surface

diphyseal shaft grows in length as a result diphyseal shaft grows in length as a result of the osteogenic activity of epiphyseal of the osteogenic activity of epiphyseal plate. plate.

BONE AND CALCIUM REGULATORY FACTORS

Somatotrophin(pituitary)

Bone Growth

Calcitonin(parafollicular cellsof thyroid)

CalciumFlux

Parathormone(parathyroid)

Bone Resorption

Osteoclasts Osteocytes“osteocytic osteolysis”

Nutritional Factors:Calcium & Vitamin D DeficiencyChild- RickettsAdult- osteomalaciaVitamin C DeficiencyScurvy- matrix not calicifiable