What does it do?
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What does it do?
Bone Tissue
Compact Bone
Spongy Bone
Spaces
Trabeculae
4 Basic Types of Bone
Long Bones
Short Bones
Flat Bones
Irregular Bones
Long Bones
Length > Width
Most appendage bones
Exceptions
Short Bones
Roughly cuboidal
Carpals
Tarsals
Flat Bones
Thin
Flat
Curvy
Irregular Bones
Don’t fit
Long Bone Structure
DiaphysisEpiphysis Epiphysis
Medullary CavityYellow Marrow
Triglycerides
Epiphysis
Epiphyseal Line
Epiphyseal Plate
Bone Exterior
Joint surfaces
Everywhere else
Covered by articular cartilage
Covered by periosteum
Periosteum
Outer layer
Inner layer
Fibrous layer Dense irregular CT
Osteogenic layerOsteoblasts
Perforating fibers
PeriosteumCellular layer
Fibrous layer
OsteocyteCompact boneCompact bone
Endosteum
Endosteum
Osteoprogenitorcell
Osteoblasts
Nuclei
Osteoclast
Osteocyte
Spongy bone
Medullary cavity
Spongy bone
Medullary cavity
Endosteum lining bony canals and covering trabeculae
Perforating canal
Perforating fibers
Periosteal blood vesselPeriosteum
Osteon
Centralcanal
Lamellae
Compactbone
Spongy bone
Osteon Concentric layers of bone matrix
Surrounding a central canal
Lamellae
Microscopic Structure of Long Bone
Centralcanal
Osteon
Collagenfiberorientation
Concentriclamellae
Nerve
Vein Artery
Lacunae
Lamellae
NerveVeinArtery
Canaliculi
Osteocytein a lacuna
Centralcanal
Flat Bone Structure
Diploë
Bone Matrix
⅓ Osteoid
Collagen + Ground substanceProvides flexibility & Resists tension
⅔ Hydroxyapatite -CaP0
4 and Ca(OH)
2
Provides hardness & Resists compression
This bone:
a. Has been demineralized
b. Has had its collagen removed
Cartilagegrows here.
Cartilageis replacedby bone here.
Long Bone – Growth in LengthInterstitial growth
Calcified cartilagespicule
Osseous tissue(bone) coveringcartilage spicules
Resting zone
Osteoblast depositingbone matrix
Proliferation zoneCartilage cells undergo mitosis.
Hypertrophic zoneOlder cartilage cells enlarge.
Ossification zoneNew bone formation is occurring.
Calcification zoneMatrix becomes calcified; cartilage cells die; matrix begins deteriorating.
1
2
3
4
Childhood Growth Hormone
Stimulates epiphyseal plate activity - cartilage production and cartilage conversion to bone
Sex Hormones Estrogen/TestosteroneStimulates epiphyseal plate activity. It causes FAST conversion of cartilage to bone and SLOW production of new cartilage.
OsteogenesisBone Deposition
OsteolysisBone Resorption
Articular cartilage
Epiphyseal plate
Bone isresorbed here.
Bone isresorbed here.
Bone is addedhere.
Bone Remodeling (Appositional Growth)
Bone Deposition/Resorption depends on Blood [Ca2+]
↓ Blood [Ca2+]
Increased intestinal Ca2+ absorption
Parathyroid glands release PTH
Decreased urinary Ca2+ excretion
Increased osteoclast activity
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