bone and ossification histo Flashcards Preview

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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

12

type of bone
process of mineralization occurs more slowly and continues long after the organic matrix is initially deposited

lamellar

13

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 -

38

– 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 –

41

lines the central medullary cavity

Endosteum –

42

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

44

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

51

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

52

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

53

Found in the marrow cavity of the diaphysis of long bones

Abundant fat cells – yellow color

Not active in hemopoiesis

yellow bone marrow

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