Electronic noises can distract you from this lecturePlease turn of all mobile phones, WAPs and PADs Bone remodellingHormonal regulation of bone formation and growthChanges in the mechanical properties of bone with age and diseaseIncorporation of other materials into boneFunctions of cartilagePhysiology of jointsAge related changes in jointsMajor pathologiesObjectiesPhysiology of bone and jointsNext slide Proiding load!bearing pillarsProiding leers"olid protection of C#" $ thora%"tore of calciumHaemopoiesis$ &nergy store 'fat( Functions of boneNext slide Remodelling of Bone Actie tissue with significant metabolic rate ')* of cardiac output(Bone recycled in +!+, years+ yr recycling in infants-rabecular bone fastest . / yr adult Compact bone slower0ia 1Basic Multicellular 2nits1 'BM2(Next slide Osteogenic cellsundifferentiated3 in periosteumformation and repairOsteoblastsma4e collagen matri% from outsiderelease al4aline phosphataseHigh PO5 precipitates CaOsteoclasts"timulated by PH-6ecalcify bone 7arge multinucleateOsteocytesin lacunaesurrounded by and maintain matri%Bone cells Next slide Rebuilding bone -eams of cells Basic Multicellular 2nit+,, day life span),, um across ), um deepOsteoclasts erode surface 'create local H8 enironment(Acid phosphatase !measured in serum!bloc4ed by pyrophosphate 'and bisphosphonates(Proteolytic en9ymes to remoe organic matri% Osteoblasts replace the eroded boneMatri% resynthesisAlkaline phosphatase and high pH)* of adult bone being remodelled at any one timeNext slide Remodeling of Bone Next slide Bone constituents Organics ':,* dry matter in all( 7ay down matri% of collagen type I in triple heli% haing high tensile strength; Collagen synthesis needs itamin C Proteoglygans $ other proteins Next slide Bone constituents Mineral 'Next slide Heavy metals in bone Most heay metals form insoluble salts with PO5 li4e Ca -herefore also incorporated into bone Physiological deto%ification remoed from body fluids usually inert in bone 'eg Pb( but held in bone for many years seere problem with radio actie metals3 eg strontium!?,3 radium3 plutonium( Cadmium stimulates osteoclast actiity hence bone loss renal to%icity increases Ca loss Copper re@uired in trace amounts to synthesise collagen matri% deficiencies rare Next slide Other substances deposited in bone -echnetium!?? pyrophosphate ta4en up into bone -etracycline during mineralisation3 tooth pre!eruption incorporated into bone and teeth 'brown staining(Next slide Bisphosphonates "table pyrophosphates Bind to bone and released to inhibit osteoclasts when they are actie AeduceB osteoporosis PagetCs disease tumour secondaries on boneNext slideOther substances deposited in bone Predictor of bone strengthBM6 measured byB2ltrasound D!ray absorption 'more accurate(&%pressed as! gramEcm/ of assessment area! - score 'referred to normal alues(Bone mineral density Next slide Bone mass against age Next slide0 0 !0 "0 #0$ge% yearsBone mass% g&cm'(alesFemalesPubertyPea) bone mass(enopauseOld age00*+,*0 Parathyroid hormone Ca homeostatisCa and PO5 remoal from bone0itamin 6 Aegulating Ca inta4e7ong!term3 stimulate bone formation+3/)!hydro%ycholecalciferolCa and PO5 remoal from boneIncreased during growthCalcitoninInhibits release of Ca from bone"eeral cyto4ines incBone morphogenic proteinIFF 'insulin!li4e growth factor(Hormonal influences on bone Next slide Frowth hormone ! depends on ageIncreases chondrocytes and bone lengtheningBone thic4ening after epiphyseal plate closure;0ia insulin li4e growth factor 'IFF(FH mostly secreted at nightAlso hCF-ro.th hormone influences bone Next slide Androgens 'testosterone(Produces growth spurt in adolescence ia FHBut induces epiphyseal plate Increase bone formation and densityOestrogen 'Oestradiol(epiphyseal plate closureIncrease bone remodelling 'in males3 from androgens(/ex hormones influence bone Next slide Oestradiol0strogenic influences on bone Next slideOsteoclast differentiationreducedOsteoblast proliferationInhibition of bone resorptionBone formationBoth effects through different cyto4ines!replicated by ralo%ifen 'estrogen! receptor specific agonist aoiding increased breast cancer ris4( Flucocorticoid Osteoporosis with e%cess 'especially ertebrae("teroid anti!inflammatories 'long term(Cushings 'e%cess AC-HEcortisol production(Children ! stress infections or steroid treatment delays bone growth1ortisol influences bone Next slide Increased stress increases bone density6ynamic loads more effectie0ia collagen!hydro%yapatite pie9o electric currents and nitric o%ide"hapes bones to optimally resist forcesGithout load bearing3 lose bone mass and strength':,* after + month(weightlessnessH BM6 higher in dominant arm of tennis players&%ercising post!menopausal women taller '+;= cm( than sedentary age!matched women(echanical influences on bone Next slide Mechanical influences on bone Next slide 2isorders of bone metabolism Osteoporosis7oss of matri% and mineral6ecreased bone massHigh ris4 of irreparable fracturesParticularly spongy bone of fore!arms 'radius(3 ertebrae and nec4 of femur . why his type of bone>higher bone turnoer and resorption rate hereProgressie with age . easier to arrest than reerseAeduced se% hormones Females . I,*3 high loss rate3 post menopausal Males . /,*3 falling testosterone3 ethanol $ othersAeduced e%ercise7ower initial bone massPoor nutrition and absorptionAace !AfricanJ&uropeanKAsian 'when other factors e@ual(&thanol abuse3 smo4ing $ numerous other factorsNext slide Osteomalacia7oss of mineral6ue to Ca deficiencyCollagen and other matri% proteins retained or unaailability of Ca 'eg itamin 6(Aeersible"ee caseAic4ets2naailability of Ca during deelopmentPermanent s4eletal defects6isorders of bone continued Next slide Matri% diseasesAare genetic defects in collagenBone is ery brittle"ometimes osteoporosis'6efectie collagen !aortic aneurisms(PagetLs diseaseIncreased bone resorption3J5, yrIncreased repair but poor replacement ! bones become deformed! wea4erMeasure al4aline phosphatase 'bone specific3 an indicator of increased bone formation(Can use bisphosphonates6isorders of bone continued Next slide MProiding articulating surfacesMCreating hollow structures 'trachea(M"ame structural functions as bone in fetus and babiesMProision of matri% for deposition ofbone during deelopment Functions of 1artilage Next slide Properties of 1artilage Next slide-ight networ4 1ollagen 7oose Aadial and attached to bone Proteoglycans /)* dry matterComposed ofBHydrated proteoglygans; glucosaminoglycans 'FAFs( attached to protein frameAttract water3 proteins and polysaccharidesBehaes as rigid gelCollagen '/,*of dry matter( inserted into bone and loops into cartilageGater and salts Chondrocytes '+!+/*(Mechanical propertiesProgressiely compresses as load is increased due to water s@uee9ed out"hape restored as load remoed; 'stress rela%ation( -herefore absorbs shoc4; Compare boneProides large matched pads ma%imising the cushioning area in joint1artilageNext slide "ynoial fluid lubricantshyaluronidate stringy glucopolysaccharidelubricin 'glycoprotein adheres to cartilage surfaceClear and iscous Clear and iscous#o fibrinogen and other clotting factors #o fibrinogen and other clotting factors 0iscoelasticity 'stringy( . ensures that is stays0iscoelasticity 'stringy( . ensures that is stays between articular cartilages; between articular cartilages;Fluid layer allows lubrication Fluid layer allows lubrication Coefficient of friction +E+, of that of an ice s4ateCoefficient of friction +E+, of that of an ice s4ate on ice on ice3oints Next slide FunctionsArticulation"hoc4 absorbing 'cushioning("ynoial fluid 'lubricant!hyaluronidate(Fibrous capsule 'sealed(Held together with ligaments '$ muscles(Bursae #on!articular bags"imilar cushions of synoial fluid3ointsNext slide OsteoarthritisMany diseases0ery common in elderly '=,*(&rosion of articular cartilages 'normal process but failure to replace(Protrusions of bone causing pain3 stiffness and noise;Aheumatoid arthritisAutoimmune inflammatory disease"ynoial membranes inflammation6estruction of cartilageOccurs in younger age groupProgressieAlso other effectsFout2ric acid precipitation2iseases of joints Next slide Sprain"tretched or torn ligament around jointor torn insertionDislocation (luxation)Opposing bones forced out of alignmentCartilage damageAascular so little repairFragments can cause further damage 2amage to jointsNext slide 4he endNext slidehttpBEEwww;mededsoft;comE@ubhttpBEEwww;@ub;ac;u4Esmrg