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25 Cards in this Set

  • Front
  • Back
Basic functional unit of the Haversian system
Components of the Haversian System
Lamellae, Lacunae, Canaliculi, Haversian canal, Volkmann's canals
Ring-like layers of ground substance
Laid down on collagen fiber framework
Spaces between lamellae containing osteocytes
Minute canals radiating from lacunae
Mechanism for communication and transport
Haversian canal
(AKA. Centeral Canal)
Contains blood vessels and nerves
Runs "vertically"
Volkmann's canals
Perpendicular channels connecting to Haversian canals
Contains blood vessels and nerves
Cylinder of compact bone in long bone(shaft) with medullary cavity
Intermedullary contains
yellow marrow (adipose)
is enclosed in diaphysis
Enlarged end of long bone with compact and trabecular bone
Site of red bone marrow at birth (but only in head of humenis and femur in adults)
Filled with spongy tissue
Between diaphysis and epiphysis
Band of cartilage serving as growth plate
Dense irregular connective tissue covering
Covers all compact bone except articular surfaces
External surface on which ligaments and tendons attatch
Dense irregular connective tissue covering
Covers all compact bone except articular surfaces
Internal (medullary cavity); contains osteoprogenator cells, osteoblasts, and osteoclasts
Generally more osteoclastic activity than osteoblast
Articular Cartilage
Layer of hyaline cartilage on articular surface of epiphyses
Medullary Cavity
Centeral portion of diaphysis; contains yellow marrow in adults
Nutrient Foramen
Opening through compact bone; allows passage of artery into medullary cavity
Ossification pathways
Embryonic bone dvelops from connective tissue model which becomes ossified
Ossification is initiated by the invasion of connective tissue by blood vessels
Osteoblasts turn connective tissue into trabecular bone at ossification center (non-lamellar--> trabecular)
Periosteum develops around connective tissue model
Sub-periosteal osteoblasts lay down compact bone on connective tissue model
Time frame for ossification
3-4 months prenatal: primary ossification begins
Birth-5 years: secondary ossification present
Adult size and shape starts when the epiphesis and parts of neocranium begin to fuse together
Endochondrial Ossification
Bone forms in hyaline cartilage precursor
Vascularization via nutrient foramen initiates ossification
Begins at primary ossification located in the diaphysis, and 1 or more secondary ossification centers located in the ephyses
Function of cartilagenous metaphysic
in Endrochondrial ossification, joins ephisyses and diaphysis of growing long bone (aka growth plate)
Intramembraneous Ossification
Bones form within loose or dense connective tissue membrane
Mesencymal cells differentiate into osteoblasts; put out osteoid fluid
Initially produces trabecular bone, then compact bone
Development path for clavicle, mandible, flat cranial bones
Purpose of continuing remodeling, rebuilding post-ossification
Maintain calcium and phosphate levels in the body
How post-ossification bone change works
Deposition and reabsorption occurs on periosteal and endosteal surfaces off the skeletal element
Osteoblast/clast activity regulated by hormones
Diamater increases through deposition>eating
Osteopenia and Osteoporosis
Increased absorption and decreased production with age leads to loss of bone mass
Linked to estrogen production
Underlies loss in height, teeth and brittle bones
When normal function is impaired=osteoperosis
(AKA Rickets) Due to vitamin D deficencies
Also lack of calcium and phosphorus absorption=reduced mineral content in bones
Can occur in children or adults