1. Bones and Skeletal Tissues
PART 1
Bones and Skeletal Tissues

2. Location and basic structure
Cartilage
Location and basic structure
Found throughout adult body
Ear and epiglottis
Articular cartilages and costal cartilage
Larynx, trachea, and nose
Intervertebral discs and pubic symphysis
Where do you find each type of cartilage?
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3. Is surrounded by perichondrium Consists primarily of water
Cartilage
Is abundant in embryo
Is surrounded by perichondrium
Consists primarily of water
Resilient tissue – springs back to original shape
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4. Types of Cartilage – Covered in CH 4
Hyaline cartilage – (glassy)
Most abundant cartilage
Provides support through flexibility
Elastic cartilage – contains many elastic fibers
Able to tolerate repeated bending
Fibrocartilage – resists strong compression and strong tension
An intermediate between hyaline and elastic cartilage
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5. Cartilages in the Adult Body
Figure 6.1
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6. Growth of Cartilage Appositional growth Interstitial growth
Chondroblasts in surrounding perichondrium produce new cartilage
Interstitial growth
Chondrocytes within cartilage divide and secrete new matrix
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7. Bones contain several types of tissues
Tissues in Bone
Bones contain several types of tissues
Dominated by bone CT
Contain nervous tissue and Blood CT
Contain cartilage in articular cartilages
Contain ET lining blood vessels
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8. Support – provides hard framework
Function of Bones
Support – provides hard framework
Movement – skeletal muscles use bones as levers
Protection of underlying organs
Mineral storage – reservoir for important minerals
Blood-cell formation – bone contains red marrow
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9. Classification of Bones
Long bones – longer than wide – a shaft plus ends
Short bones – roughly cube-shaped
Flat bones – thin and flattened, usually curved
Irregular bones – various shapes, do not fit into other categories
Give an example of each type of bone
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10. Classification of Bones
Figure 6.2
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11. Compact bone – dense outer layer of bone
Gross Anatomy of Bones
Compact bone – dense outer layer of bone
Spongy (cancellous) bone – internal network of bone
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12. Structure of a Typical Long Bone
Diaphysis – “shaft” of a bone
Epiphysis – ends of a bone
Blood vessels – well vascularized
Medullary cavity – hollow cavity filled with yellow marrow
Membranes
Periosteum, perforating fibers (Sharpey’s fibers), and endosteum
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13. Structure of a Long Bone
Figure 6.3a–c
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14. Structure of Short, Irregular, and Flat Bones
Flat bones, short bones, and irregular bones
Contain bone marrow but no marrow cavity
Diploë
Internal spongy bone of flat bones
Figure 6.4
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15. Gross Anatomy of Bones Bone design and stress
Anatomy of a bone reflects stresses
Compression and tension greatest at external surfaces
Figure 6.5a
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16. Superficial surfaces of bones reflect stresses on them
Bone Markings
Superficial surfaces of bones reflect stresses on them
There are three broad categories of bone markings
Projections for muscle attachment
Surfaces that form joints
Depressions and openings
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17. Bone Markings
Table 6.1
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18. Microscopic Structure of Compact Bones
Figure 6.6
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19. Bones and Skeletal Tissues
PART 2
Bones and Skeletal Tissues

20. Chemical Composition of Bone
35% organic components
Composed of cells, fibers, and organic substances
Collagen – abundant
65% inorganic mineral salts
Primarily calcium phosphate
Resists compression
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21. Ossification (osteogenesis) – bone-tissue formation
Bone Development
Ossification (osteogenesis) – bone-tissue formation
Membrane bones – formed directly from mesenchyme
Intramembranous ossification
Other bones – develop initially from hyaline cartilage
Endochondral ossification
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22. Intramembranous Ossification
Figure 6.9, steps 1–2
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23. Intramembranous Ossification
Figure 6.9, steps 3–4
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24. Endochondral Ossification
All bones except some bones of the skull and clavicles
Bones are modeled in hyaline cartilage
Begins forming late in the second month of embryonic development
Continues forming until early adulthood
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25. Stages in Endochondral Ossification
Figure 6.10
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26. Anatomy of Epiphyseal Growth Areas
In epiphyseal plates of growing bones
Cartilage is organized for quick, efficient growth
Cartilage cells form tall stacks
Chondroblasts at the top of stacks divide quickly
Pushes the epiphysis away from the diaphysis
Lengthens entire long bone
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27. Anatomy of Epiphyseal Growth Areas
Older chondrocytes signal surrounding matrix to calcify
Older chondrocytes then die and disintegrate
Leaves long trabeculae (spicules) of calcified cartilage on diaphysis side
Trabeculae are partly eroded by osteoclasts
Osteoblasts then cover trabeculae with bone tissue
Trabeculae finally eaten away from their tips by osteoclasts
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28. Organization of Cartilage within Epiphyseal Plate of Growing Long Bone
Figure 6.11
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29. Postnatal Growth of Endochondral Bones
During childhood and adolescence
Bones lengthen entirely by growth of the epiphyseal plates
Cartilage is replaced with bone CT as quickly as it grows
Epiphyseal plate maintains constant thickness
Whole bone lengthens
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30. Hormonal Regulation of Bone Growth
Growth hormone – produced by the pituitary gland
Stimulates epiphyseal plates
Thyroid hormone – ensures that the skeleton retains proper proportions
Sex hormones (estrogen and testosterone)
Promote bone growth
Later induces closure of epiphyseal plates
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31. Postnatal Growth of Endochondral Bones
As adolescence draws to an end
Chondroblasts divide less often
Epiphyseal plates become thinner
Cartilage stops growing
Replaced by bone tissue
Long bones stop lengthening when diaphysis and epiphysis fuse
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32. Bone is dynamic living tissue
Bone Remodeling
Bone is dynamic living tissue
500 mg of calcium may enter or leave the adult skeleton each day
Cancellous bone of the skeleton is replaced every 3 – 4 years
Compact bone is replaced every 10 years
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33. Postnatal Growth of Endochondral Bones
Growing bones widen as they lengthen
Osteoblasts – add bone tissue to the external surface of the diaphysis
Osteoclasts – remove bone from the internal surface of the diaphysis
Appositional growth – growth of a bone by addition of bone tissue to its surface
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34. Bone deposit and removal Bone remodeling
Occurs at periosteal and endosteal surfaces
Bone remodeling
Bone deposition – accomplished by osteoblasts
Bone reabsorption – accomplished by osteoclasts
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35. Remodeling, Spongy Bone
Figure 6.12
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36. Osteoclast – A Bone-Degrading Cell
A giant cell with many nuclei
Crawls along bone surfaces
Breaks down bone tissue
Secretes concentrated HCl
Lysosomal enzymes are released
Figure 6.13a
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37. Repair of Bone Fractures
Simple and compound fractures
Treatment by reduction
Closed reduction
Open reduction
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38. Stages of Healing a Fracture
Figure 6.14
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39. Common Types of Fractures
Table 6.2 (1 of 3)
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40. Common Types of Fractures
Table 6.2 (2 of 3)
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41. Common Types of Fractures
Table 6.2 (3 of 3)
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42. Disorders of Bones Osteoporosis Characterized by low bone mass
Bone reabsorption outpaces bone deposition
Occurs most often in women after menopause
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43. Osteoporosis
Figure 6.15
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44. Disorders of Bones Osteomalacia Rickets
Occurs in adults – bones are inadequately mineralized
Rickets
Occurs in children – analogous to osteomalacia
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45. Disorders of Bones Paget’s disease Osteosarcoma
Characterized by excessive rate of bone deposition
Osteosarcoma
A form of bone cancer
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46. The Skeleton Throughout Life
Cartilage grows quickly in youth
Skeleton shows fewer chondrocytes in the elderly
Bones are a timetable
Mesoderm
Gives rise to embryonic mesenchyme cells
Mesenchyme
Produces membranes and cartilage
Membranes and cartilage ossify
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47. The Skeleton Throughout Life
Skeleton grows until the age of 18–21 years
In children and adolescents
Bone formation exceeds rate of bone reabsorption
In young adults
Bone formation and bone reabsorption are in balance
In old age reabsorption predominates
Bone mass declines with age
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