skeletal system: osseous tissue & skeletal structure chapter 6
DESCRIPTION
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Skeletal System:Skeletal System:Osseous Tissue & Osseous Tissue & Skeletal StructureSkeletal Structure
Chapter 6Chapter 6
28 million Americans have 28 million Americans have OSTEOPOROSISOSTEOPOROSIS
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Skeletal System: IntroSkeletal System: Intro Includes: bones, cartilage, ligaments, & Includes: bones, cartilage, ligaments, &
other connective tissuesother connective tissues Functions:Functions:
1.1. SupportSupport2.2. StorageStorage: :
– Mineral reserve (CaMineral reserve (Ca2+2+ & P ions) & P ions)– Lipid (fat) in yellow marrowLipid (fat) in yellow marrow
3.3. Blood Cell ProductionBlood Cell Production4.4. ProtectionProtection: brain, spinal cord, lungs: brain, spinal cord, lungs5.5. Movement & LeverageMovement & Leverage
Histology of Bone: Matrix & CellsHistology of Bone: Matrix & Cells MatrixMatrix= ground substance & protein fibers= ground substance & protein fibers
– SolidSolid calcium salts (i.e. Calcium Phosphate) calcium salts (i.e. Calcium Phosphate)– Protein fibers: collagen and othersProtein fibers: collagen and others
3 types of cells:3 types of cells:1.1. OsteoblastsOsteoblasts
– Imp. for fracture repairImp. for fracture repair– Osteogenesis-bone birthOsteogenesis-bone birth
2.2. OsteoclastsOsteoclasts: Osteolysis (bone break down) / re-: Osteolysis (bone break down) / re-absorptionabsorption
3.3. OsteocytesOsteocytes– Lay down mineral content of matrixLay down mineral content of matrix– MaturedMatured osteoblasts trapped in bone matrix osteoblasts trapped in bone matrix
Histological DifferencesHistological Differences Compact BoneCompact Bone1.1. OsteonOsteon: basic : basic
unitunit– Central Central
Haversian Haversian CanalCanal
– LacunaeLacunae– OsteocyteOsteocyte– LamellaeLamellae
Calcified Calcified matrix matrix layerslayers
– Canaliculi Canaliculi
Spongy BoneSpongy Bone1.1. No OsteonsNo Osteons
– Lamellae= Lamellae= trabeculaetrabeculae
– Osteocytes in lacuna Osteocytes in lacuna connected by connected by canaliculicanaliculi
2.2. Marrow spaces: inside Marrow spaces: inside spongy bonespongy bone– nutrients & wastes nutrients & wastes
diffusediffuse– Blood cell formationBlood cell formation
Spongy Bone
Compact Bone
Compact Bone= Cortex•Covers spongy bone•Osteons parallel to long axis•Good unidirectional support
Diaphysis= shaft•Compact•Spongy•Marrow
MetaphysisEpiphysis= ends
Spongy Bone= ends & flat bones•Lines marrow & lighter to move•Trabeculae cross-bracing•Good multidirectional support
Articular Cartilage•Joint surfaces
Long Bone Layers ArrangementLong Bone Layers Arrangement PeriosteumPeriosteum
– Fibrous outer layer (dense regular C.T.)Fibrous outer layer (dense regular C.T.)– Binds to joint capsule & tendonsBinds to joint capsule & tendons
Compact BoneCompact Bone Spongy BoneSpongy Bone: trabeculae: trabeculae EndosteumEndosteum
– Covers trabeculae, lines marrow cavityCovers trabeculae, lines marrow cavity– Cells: osteoclasts, osteoblastsCells: osteoclasts, osteoblasts
Medullary CavityMedullary Cavity (AKA marrow cavity) (AKA marrow cavity)– Red marrow in spongy boneRed marrow in spongy bone
Function: Function: Hemopoiesis-Hemopoiesis- blood cell formation blood cell formation– Yellow marrow in marrow cavity: fat storageYellow marrow in marrow cavity: fat storage
Periosteum
Endosteum
Osteoblasts
Osteoclast
Compact Bone
Spongy
Osteocytes
Long Bone StructureLong Bone Structure
Bone: Development & Growth Bone: Development & Growth TermsTerms
Skeletal growth Skeletal growth – Determines size & proportion of Determines size & proportion of
bodybody– Starts 6 wks. after egg fertilization Starts 6 wks. after egg fertilization
until approx. 18-25 years olduntil approx. 18-25 years old
Types of Bone GrowthTypes of Bone Growth Ossification: Ossification:
– Process of replacing other tissues w/ bone Process of replacing other tissues w/ bone Developing New BoneDeveloping New Bone
Increasing Diameter (width) of BoneIncreasing Diameter (width) of Bone1.1. Appositional growthAppositional growth
Lengthening Bones (growing taller)Lengthening Bones (growing taller)1.1. Epiphyseal plate endochondral ossificationEpiphyseal plate endochondral ossification
Appositional GrowthAppositional Growth Increases diameter by forming new Increases diameter by forming new
osteonsosteons
Epiphyseal Plate LengtheningEpiphyseal Plate Lengthening Epiphyseal plate: cartilageEpiphyseal plate: cartilage
Cartilage plate in metaphysis Cartilage plate in metaphysis Grows & divides pushing epiphyses away from Grows & divides pushing epiphyses away from
diaphysisdiaphysis Matrix calcifiesMatrix calcifies chrondrocytes eventually die chrondrocytes eventually die
Osteoblasts replace calcified cartilage with Osteoblasts replace calcified cartilage with bone bone
When bone growth> cartilage growthWhen bone growth> cartilage growth stop stop growing growing epiphyseal plate becomes ossifiedepiphyseal plate becomes ossified epiphyseal line epiphyseal line
InvadingCalcium
Osteoblasts
Chondrocytes: New & Old
Requirements for Normal Bone Requirements for Normal Bone GrowthGrowth
Dietary minerals especially CaDietary minerals especially Ca2+2+ & P & P Vitamin DVitamin D rickets rickets Vitamin A & CVitamin A & C scurvy (decreases scurvy (decreases
collagen synthesis)collagen synthesis) HormonesHormones
HGHHGH Thyroid hormonesThyroid hormones Sex hormonesSex hormones Calcium metabolism: parathormone, Calcium metabolism: parathormone,
calcitonincalcitonin
Hormone Regulation of Bone GrowthHormone Regulation of Bone Growth Human Growth HormoneHuman Growth Hormone (HGH) (HGH)
Released by pituitary glandReleased by pituitary gland GigantismGigantism: overproduce HGH b4 puberty: overproduce HGH b4 puberty Pituitary DwarfismPituitary Dwarfism: inadequate HGH : inadequate HGH
Sex hormonesSex hormones Speed up bone growth osteoblast activitySpeed up bone growth osteoblast activity
cartilage formationcartilage formation epiphyseal lineepiphyseal line Growth spurtsGrowth spurts Treatment for osteoporosisTreatment for osteoporosis
Calcitonin & parathyroid hormone: Calcitonin & parathyroid hormone: regulate [Caregulate [Ca2+2+] ]
Hormone Regulation of Hormone Regulation of CalciumCalcium [Ca[Ca2+2+] depends on activities of: ] depends on activities of:
– bones (osteoclasts)bones (osteoclasts) Store in bone or release to bloodStore in bone or release to blood
– intestinal tract (absorption)intestinal tract (absorption)– kidneys (excretion)kidneys (excretion)
[Ca[Ca2+2+] maintained by 2 hormones:] maintained by 2 hormones: Calcitonin: Calcitonin: thyroid glandthyroid gland Parathyroid:Parathyroid: parathyroid gland parathyroid gland
Calcitonin & ParathormoneCalcitonin & Parathormone CalcitoninCalcitonin: :
Secreted by thyroidSecreted by thyroid Responds to Responds to
[Ca[Ca2+2+] ] Net effect: [CaNet effect: [Ca2+2+]]
Inhibit Inhibit osteoclastsosteoclasts
Ca intestinal Ca intestinal absorption rateabsorption rate
Ca excretion Ca excretion rate at kidneysrate at kidneys
Parathyroid Parathyroid hormonehormone:: Secreted by Secreted by
parathyroidparathyroid Responds to [CaResponds to [Ca2+2+] ] Net effect: [CaNet effect: [Ca2+2+] ]
Stimulate Stimulate osteoclastsosteoclasts
Ca intestinal Ca intestinal absorption rateabsorption rate
Ca excretion at Ca excretion at kidneyskidneys
Remodeling & Homeostatic Remodeling & Homeostatic MechanismsMechanisms
Osteoblast/ osteoclast activity balancedOsteoblast/ osteoclast activity balanced 18% bone content replaced every year18% bone content replaced every year [Ca[Ca2+2+] must be closely controlled] must be closely controlled
– Hormone Regulation: Calcitonin & Hormone Regulation: Calcitonin & ParathormoneParathormone 30%30% nerves & muscle unresponsive nerves & muscle unresponsive 35%35% convulsions b/c nerves excitable convulsions b/c nerves excitable 50%50% death death
Aging & Skeletal SystemAging & Skeletal System OsteopeniaOsteopenia:: decreasing ossification decreasing ossification
– Reduce bone mass in 30’s & 40’sReduce bone mass in 30’s & 40’s– Osteoblast activity, osteoclast activity normalOsteoblast activity, osteoclast activity normal– Normally, females lose (8% mass), males (3%) Normally, females lose (8% mass), males (3%)
per decadeper decade OsteoporosisOsteoporosis: significant loss of bone mass : significant loss of bone mass
to compromise normal functionto compromise normal function– More in females after menopauseMore in females after menopause– fragilityfragility fx’s & healing impaired (esp. fx’s & healing impaired (esp.
vertebrae)vertebrae)– Treatments (sex hormones: estrogen), Treatments (sex hormones: estrogen),
exercise: slow effects, but can’t preventexercise: slow effects, but can’t prevent
OsteoporosisOsteoporosis
NormalNormal Compression Compression FractureFracture
Bone Repair1.1. BleedBleed fx hematoma fx hematoma2.2. Endosteum & Periosteum cells divideEndosteum & Periosteum cells divide callus callus3.3. Callus middleCallus middle cartilage forms, callus edges cartilage forms, callus edges bone bone4.4. Osteoblasts replace cartilageOsteoblasts replace cartilage spongy bone spongy bone5.5. Bone remodelling by osteoclasts/ blasts x 4 mo- yearBone remodelling by osteoclasts/ blasts x 4 mo- year6.6. Bone starts to Bone starts to remodel with weight bearingremodel with weight bearing
Callus InternalEdge: Bone
Callus ExternalEdge: Bone
Callus Middle:Cartilage
Spinal Fusion w/Spinal Fusion w/Bone GraftBone Graft
Bone Graft
Pedicle Screws
Rod Placement for Displaced Rod Placement for Displaced FxFx
FRACTURES
Anatomy of Bones:Anatomy of Bones:Classification of BonesClassification of Bones
Types/ Types/ Shapes:Shapes:– LongLong– ShortShort– FlatFlat– IrregularIrregular
Examples:Examples:– Humerus, Humerus,
femurfemur– Carpals, Carpals,
tarsalstarsals– Scapula, Scapula,
sternumsternum– VertebraeVertebrae
Examples of Bone ShapesExamples of Bone Shapes
Articulations (joints): Articulations (joints): ClassificationClassification
Functional Classification:Functional Classification: SynarthrosisSynarthrosis: immovable joint: immovable joint
Skull, teeth, epiphyseal plateSkull, teeth, epiphyseal plate AmphiarthrosisAmphiarthrosis: slightly movable: slightly movable
Between tibia & fibula, front of pelvisBetween tibia & fibula, front of pelvis DiarthrosisDiarthrosis: freely movable: freely movable
SynovialSynovial: joint capsule & synovial fluid filled : joint capsule & synovial fluid filled joints (e.g. knee, shoulder, hip)joints (e.g. knee, shoulder, hip)
Types of Diarthrotic JointsTypes of Diarthrotic Joints UniaxialUniaxial
– One directionOne direction– Hinge: elbow, Hinge: elbow,
kneeknee
BiaxialBiaxial– Two directionsTwo directions– Wrist Wrist
Triaxial: Triaxial: 3 directions3 directions– Ball & Socket: hip, Ball & Socket: hip,
shouldershoulder Flex/ ExtendFlex/ Extend Abduct/ AdductAbduct/ Adduct Internal/ External Internal/ External
RotationRotation
– Freely moving joints Freely moving joints are less stableare less stable
– DislocationDislocation= when = when articulating surfaces articulating surfaces are forced out of are forced out of positionposition
General Structures in Diarthrotic General Structures in Diarthrotic JointsJoints
MenisciMenisci: fibrocartilage discs : fibrocartilage discs b/w joint surfacesb/w joint surfaces
Fat padsFat pads: protection & : protection & paddingpadding
Joint capsuleJoint capsule: joint synovial : joint synovial membranemembrane
LigamentsLigamentsBursaeBursae: synovial fluid pockets: synovial fluid pockets
Marrow CavitySpongy Bone
Synovial MembraneArticular CartilageJoint Cavity
Compact Bone
Joint CapsuleBursaMeniscusExtracapsular LigamentIntracapsular Ligament
OsteoarthritisOsteoarthritis
Total Knee & Hip Total Knee & Hip ReplacementsReplacements
Joint Movement Clinical NamesJoint Movement Clinical Names Flexion/ Extension Flexion/ Extension
RotationRotation– Internal or externalInternal or external
Abduction/ AdductionAbduction/ Adduction Specialties:Specialties:
– WristWrist: ulnar & radial deviation: ulnar & radial deviation– Ankle/ footAnkle/ foot: inversion/ eversion: inversion/ eversion– AnkleAnkle: dorsiflexion/ plantarflexion: dorsiflexion/ plantarflexion– ForearmForearm: pronation/ supination: pronation/ supination– ScapulaScapula: elevate/ depress: elevate/ depress