Flashcards in bone and ossification histo Deck (53):
1
makes up the greater portion of the matrix
Inorganic elements – calcium, magnesium, and sodium
2
Ground substance is calcified – becomes hard and brittle
bone
3
organic elements of bone
(collagen, protein polysaccharide and chondroitin sulfate)
4
functions of bone
Internal support of the body
Attachment of muscles and tendons for locomotion
Contains the bone marrows – blood forming elements
Protects vital organs of the cranial and thoracic cavities
For storage of calcium in the body
5
types of bone based on the organization of its type I collagen fibers
lamellar
woven
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type of bone
collagen fibers are arranged in an irregular feltwork
fabricated during periods of rapid bone growth
woven
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type of bone
hypercellular, with large osteocytes and lacunae, distributed in a haphazard fashion, long axes follow the direction of the neighboring collagen fibers
woven
8
type of bone
higher mineral content than that of lamellar bone; deposited outside of collagen fibers
woven
9
type of bone
resist forces equally in all directions; weaker, less rigid, more flexible than lamellar bone (greenstick fracture)
woven
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type of bone
collagen fibers are deposited in parallel arrays
lamellar
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type of bone
synthesized more slowly, less cellular, smaller osteocytes and lacunae, distributed in a more organized fashion along the more regular collagen lamellae
lamellar
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type of bone
process of mineralization occurs more slowly and continues long after the organic matrix is initially deposited
lamellar
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type of bone
has greater rigidity and tensile strength, less elasticity than woven bone.
lamellar
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FORMS OF LAMELLAR BONES
Cancellous or Spongy bone (substancia spongiosa)
Compact bone (substancia compacta)
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LONG BONE
– thick walled hollow cylinder w/ a central medullary cavity containing the bone marrow
Shaft
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LONG BONE
ends of long bones made up of spongy bone covered by a thin cortex of compact bone
Epiphysis –
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LONG BONE
– separates the epiphysis from the diaphysis
Epiphyseal plate
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LONG BONE
a transitional region connecting the epiphyseal plate to the diaphysis
Metaphysis
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long bone
a layer of specialized CT w/ osteogenic potential
Periosteum
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long bone
a thin cellular layer w/ osteogenic properties covering the marrow cavity
Endosteum
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Found in the flat bones of the face and skull
Layer of spongy bone between 2 layers of compact bone forming an outer and inner table
diploe
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bone cells
Osteoprogenitor cells
2. Osteoblasts
3. Osteocytes
4. Osteoclasts
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type of bone cells
Undifferentiated cells
On free bony surfaces,
endosteum, periosteum,
lining of the Haversian
canal, epiphyseal plate
With pale staining
nucleus and faintly
basophilic cytoplasm
Osteoprogenitor cells
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type of osteoprogenitor cells
Divide – (bone - forming cells)
osteoblasts
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type of osteoprogenitor cells
Unite – (bone - destroying cells)
osteoclasts
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Bone forming cells responsible for the development of the bony matrix
Location: surfaces of developing bones
Arranged in an epitheloid layer of cuboidal cells
osteoblasts
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Cells of fully formed bones in the lacunae of calcified matrix
An osteoblast is surrounded by bone matrix in its development
Flattened cell body inside the lacunae
osteocytes
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Giant multinucleated cells closely associated with areas of resorption
Found in shallow concavities of the bone surface called Lacuna of Howship
osteoclasts
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osteoclasts are found in shallow concavities of the bone surface called
Lacuna of Howship
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Active in bone resorption
Ruffled border – radial striations found close to the bone
osteoclasts
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Irregular branching bony spicules forming a network of interconnecting spaces containing bone marrow
With thin trabeculae made up of irregular lamellae of bone with lacunae containing osteocytes
spongy bone
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Absence of haversian system
Trabeculae lined by endosteum containing osteoprogenitor cells, osteoblasts & osteoclasts
spongy bone
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Parallel columns made up of concentric bony layers surrounding the haversian canal
Compact bone:
34
haversian channel with the concentric bony lamellae
Haversian system -
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at right angle to the haversian canal
Volkmann’s channel -
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numerous minute interconnecting canals
Canaliculi -
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found between Haversian systems formed as a result of the continuous resorption and redeposition of bone
Interstitial lamellae -
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– found at the outermost portion of the compact bone that extends around the circumference of the shaft
Periosteal / External Circumferential Lamellae
39
surrounds the central medullary cavity
Endosteal / Inner Circumferential Lamellae –
40
fibrous tissue covering the outersurface of the bone; bound to the underlying bone by Sharpey’s fibers
Periosteum –
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lines the central medullary cavity
Endosteum –
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Between lamellae are _________ in lacuna
osteocytes
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histogenesis of bone
Intramembranous Ossification – occurs directly in primitive CT
2. Intracartilaginous / Endochondral Ossification – replacement of cartilage by bone
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histogenesis of bone
occurs directly in primitive CT
Intramembranous Ossification –
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histogenesis of bone
replacement of cartilage by bone
2. Intracartilaginous / Endochondral Ossification –
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when bone arises in tissues not belonging to the skeletal system or in CT w/o osteogenic properties
Ectopic bone formation –
47
Bone formation occurs directly in primitive CT w/o cartilage formation
Commonly seen in the flat bones of the face & skull
Intramembranous Ossification
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Involves the replacement of a cartilage model by bone
Cartilage destruction is a pre-requisite
Involves the bones of the entire skeletal system except the bones of the face & skull
Intracartilaginous / Endochondral Ossification
49
Occurs later & appears at birth
Sequence of changes similar to that in the diaphyses
Less bone destruction & no formation of a single marrow cavity
What remains is spongy / cancellous bone with a thin plate of compact bone surrounding it
EPIPHYSEAL OSSIFICATION
50
Imbalance between bone resorption and bone formation.
Reduced bone mineral density
Increased bone fragility & incidence of fracture
OSTEOPOROSIS
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Blood clot replaced by vascularized granulation tissues
Initial formation of provisional callus (hyaline cartilage) from granulation tissues
Provisional callus transformed into temporary callus that unites the fractured bone
bone repair
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Temporary callus is replaced by woven bone leading to a bony union of the fracture
Woven bone is transformed into compact bone and excess bone is resorbed.
bone repair
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