Bone Presentation Concept

8/3/2019 Bone Presentation Concept

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Bone TissueAZIZAH

KHARISSUTRISNO


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Bone Tissue

Dynamic tissue that continually remodels itself

Bones and bone tissue

bone or osseous tissue is a connective tissue with amatrix hardened by minerals(calcium phosphate)

bones make up the skeletal system

individual bones are made up of bonetissue, marrow, cartilage & periosteum

Functions of the skeletal system

support, protection, movement, blood formation,mineral reservoir, pH balance & detoxification


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Shapes of Bones


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Structure of a Flat Bone

External and internalsurfaces of flat bone

are composed of

compact bone

Middle layer is spongybone (diploe). No

marrow cavity

Blow to the skull may

fracture outer layerand crush diploe, but

not harm inner

compact bone

GueGantenk

Kan???

Hihihi


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Structure of a Long Bone

Periosteum &

articular

cartilage

Compact &spongy bone

Endosteum

Yellow marrow


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Bone Tissue: Supportive Connective Tissue

Consist of

1. Cells

1. Extracellular Matrix


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Bone Cells

In addition to Osteocytes, the mature bone cells

found within the matrix of bone tissue, there arethree other cells that are associated with bones

Osteoprogenitorcells

Osteoblasts Osteoclasts


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Bone Cells

Osteoprogenitor cells Derived from mesenchymal cells

Can undergo mitosis

Mature into osteoblasts, Osteoclast, or Kondroblast


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Bone Cells

Osteoblasts Responsible for osteogenesis create bone tissue

Mature into osteocytes or Osteoclast


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Bone Cells

Osteoclasts Secrete enzymes for osteolysis resorb/break

down bone tissue

Necessary for calcium homeostasis


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Bone Cells


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Matrix of Osseous Tissue


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Matrix of Osseous Tissue Dry weight is 1/3 organic & 2/3 inorganic matter

Organic matter

collagen, glycosaminoglycans, proteoglycans &glycoproteins

Inorganic matter 85% hydroxyapatite (crystallized calcium phosphate salt)

10% calcium carbonate

other minerals Combination provides for strength & resilience

minerals resist compression; collagen resists tension


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Role of Collagen & Minerals


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Two Kinds of Bone

All bones have a

combination of

1. spongy(cancellous)

2. compact

(dense) bone

tissue


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Compact vs. spongy bone

Compact bone

External layer

Arranged in osteons

Lamellae are foundaround periphery and

between osteons

Central canals connected

to each other byperforating canals

Spongy bone

No osteons

Arranged in trabeculae

Major type of tisse inshort, flat, irregular

bones

Much lighter than

compact bone Supports red bone

marrow


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Compact vs. spongy bone


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Compact Bone

Compact bone is arranged in units called osteons or

Haversian systems.

Osteons (Haversian canal) contain blood vessels,

lymphatic vessels, nerves


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Compact Bone

Surrounding this canal are concentric rings of osteocytes along with the

calcified matrix.

Perforating canals or Volkmann canals

branches from nutrient arteries that run perpendicular to the

haversian canals Circumferential or outer lamellae


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Compact Bone

Osteon is concentric rings (lamellae) of calcified matrix surrounding

a vertically oriented blood vessel

Osteocytes are found in spaces called lacunae

Osteocytes communicate through canaliculi filled with extracellular

fluid that connect one cell to the next cell

Interstitial lamellae represent older osteons that have been

partially removed during tissue remodeling


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Spongy Bone

Spongy (cancellous) bone does not contain

osteons. It consists of trabeculae surrounding

many red marrow filled spaces.

It forms most of the structure of short, flat,and irregular bones, and the epiphyses of

long bones.

Spongy bone tissue is light and supports andprotects the red bone marrow.


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Spongy Bone

Spongelike appearance formed by rods and

plates of bone called trabeculae

spaces filled with red bone marrow

Trabeculae have few osteons or haversian

canals

no osteocyte is far from blood of bone marrow

Provides strength with little weight

trabeculae develop along bones lines of stress


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Bone Formation and Growth

Ossification - Process of converting other tissues

to bone; begins around week 6-8 of

embryological development

Two types of ossification processes occur

during embryological formation:

Intramembranous

Endochondral


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Intramembranous Ossification

Forms flat bones of skull, mandible, clavicle

Replacement of mesenchymal membrane with osseous

tissue Mesenchymal cells differentiate to osteoprogenitor cells,

which then become osteoblasts

Osteoblasts create spongy bone, which then remodels

into compact bone where necessary


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Intramembranous Ossification


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Endochondral Ossification Most bones formed this way

Mesenchyme creates Cartilage model, which gets replaced by bone

Replacement begins in middle (diaphysis) & follows in ends

(epiphyses)


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Chondrocytes at the center of the growingcartilage model enlarge and then die as thematrix calcifies.

Cartilagemodel

Copyright 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Endochondral Ossification

Cartilage model grows in length(interstitialgrowth) & in width

(appositionalgrowth)


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Figure 5.7

Enlargingchondrocytes within

calcifying matrix

Chondrocytes at the

center of thegrowing cartilagemodel enlarge andthen die as thematrix calcifies.

Newly derived osteoblasts cover theshaft of the cartilage in a thin layer ofbone.

Cartilagemodel

Bone

formation

Epiphysis

Diaphysis


Theperichondrium, whichsurrounded the cartilage model, now

must be referred to as the

periosteum.


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Figure 5.7


calcifying matrix

Chondrocytes at the


Newly derived

osteoblasts coverthe shaft of thecartilage in a thinlayer of bone.

Blood vessels penetrate thecartilage. New osteoblasts forma primary ossification center.

Cartilagemodel

Bone

formation

Epiphysis

Diaphysis Marrowcavity

Primaryossificationcenter

Bloodvessel



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Figure 5.7


calcifying matrix

Chondrocytes at the


Newly derived

osteoblasts coverthe shaft of thecartilage in a thinlayer of bone.

Blood vessels penetrate

the cartilage. Newosteoblasts form aprimary ossificationcenter.

Bone tissuecontinues toreplace cartilageof the diaphysis,and & continues

toward eachepiphysis.

Cartilagemodel

Bone

formation

Epiphysis

Diaphysis Marrowcavity


Bloodvessel

Marrowcavity

Bloodvessel


The medullary

cavity begins to

hollow out


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Blood vessels invade the epiphyses and osteoblasts form secondarycenters of ossification.Cartilage remains only at the ends (articular cartilage) & at metaphysis(epiphyseal plate)


calcifying matrix

Chondrocytes at thecenter of thegrowing cartilagemodel enlarge andthen die as the

matrix calcifies.

Newly derivedosteoblasts coverthe shaft of thecartilage in a thinlayer of bone.

Blood vessels penetratethe cartilage. Newosteoblasts form aprimary ossificationcenter.

The bone of the shaftthickens, and thecartilage near eachepiphysis is replacedby shafts of bone.

Cartilagemodel

Boneformation

Epiphysis

Diaphysis Marrow

cavity


Bloodvessel

Marrowcavity

Bloodvessel

Secondaryossificationcenter

Epiphysealcartilage

Articularcartilage

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Bone Presentation Concept