functions of bone • categories of bone • histology of

Osseous Tissue• Categories of bone

• Functions of bone

• Histology of osseous tissue

• Bone development (osteogenesis)

• Select Bone disorders

General Functions of BonesSupport

Protection

Movement

Storage

Blood cell production ----term?

General Bone Classifications

Examples

Long bones (i.e.)

Short bones

Flat bones

Sesamoid bones

Irregular bones

Wormian bones

Sutural [Wormian] bones.

Bone Anatomy Anatomy of a Long Bone

Diaphysis

Epiphysis

Metaphysis

Epiphyseal Growth Plate (line)

Figure 6.3a-b

Proximalepiphysi

s

(b)

Epiphyseal

line

Articulacartilag

e

Periosteum

Spongy bone

Compact boneMedullary

cavity (linedby

endosteum)

Compact bone

Diaphysis

Distalepiphysi

s

Diaphysis

Epiphysis

Metaphysis

Epiphyseal Growth Plate (line)

Structure of a Flat Bone• External and internal surfaces of

flat bone are composed of compact bone

• Middle layer is spongy bone (diploe).

Bone Cells OriginFunction Features Osteogenic

Osteoblasts

Osteocytes

Osteoclasts

Copyright © 2010 Pearson Education, Inc. Figure 6.4a-b

(a) Osteogenic cell (b) Osteoblast

Stem cellcell responsiblefor bone growth

Figure 6.4c-d

Osteoclast

What is this and what is going on here?

Bone Anatomy Outside Periosteum 2 layered membrane

1. Outer fibrous layer (Sharpey’s Fibers~see image)

2. Inner osteogenic layer contains osteoblasts, osteoclasts, and osteogenic cellsInside Medullary Cavity (inside?)

EndosteumContains osteoblasts, osteoclasts, and osteoprogenitor or osteogenic cells

Bone---a composite material

Matrix of Bone 65% inorganic 35% organic

Bone Histology

2 types of Bone (Compact and Spongy) 1. Compact Bone

consists of organized lamellae (layers or plates) 3 arrangements---and associated descriptive term

1. Concentric lamellae2. Interstitial lamellae3. Circumferential lamellae (All with collagen inside)

Canals central canals perforating canals canaliculi

Figure 6.7a-c

Perforating (Volkmann’s) canal

Perforating (Sharpey’s) fibersPeriosteal blood

vesselPeriosteum

Lacuna (withosteocyte)

(a)

(b)

(c)

Lacunae

Lamellae

NerveVein

ArteryCanaliculi

Osteocytein a lacuna

Circumferentiallamellae

Osteon(Haversian

system)

Central(Haversian)

canal

Central

canalInterstitial lamellae

Lamellae

Compact

bone

Spongy bone

Figure 6.6

Structures

in thecentralcanal

Artery with

capillariesVeinNerve

fiber

Lamellae

Collagenfibersrun in

differentdirection

s

Twistingforce

Fig. 6.5

Bone Histology

2. Cancellous or Spongy Lamellae

Trabeculae---no Osteons!

These are oriented along lines of stress and provide structural strength to the bone.

Fig. 6.4

Ossification or Osteogenesis (bone formation)

1. Intramembranous ( skull bones and mandible)

Osteoblasts differentiate directly from mesenchyme (embryonic tissue) and secrete osteoid

2. Endochondral (most other bones) Ossification takes place within a piece of hyaline cartilage, the shape resembling the bone.

Epiphyseal Plates

Bone RemodelingWolff’s law: A bone grows or remodels in response to forces or demands placed

upon it.Observations supporting Wolff’s law:

Handedness Larger bony projections

Hormonal influences of calcium and bone deposition/resorption/plate closure

Calcitonin (from, target, action)

PTH (from, target, action)

Estrogen and Testosterone

Injury to plate?

Bone Fractures Open/compoundClosed/simpleComminutedGreenstickImpacted or compressionStress

Bone disorders

OsteoporosisAcromegalyGigantismOsteomalacia and rickets ~ vit. D deficency

Osteoporosis

Page 138

Effects of Osteoporosis

functions of bone • categories of bone • histology of

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