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Skeletal Cartilages
• Contain no blood vessels or nerves
• Dense connective tissue girdle of perichondrium contains blood vessels for nutrient delivery to cartilage
Copyright © 2010 Pearson Education, Inc. Figure 6.1
Axial skeleton
Appendicular skeleton
Hyaline cartilages
Elastic cartilages
Fibrocartilages
Cartilages
Bones of skeleton
EpiglottisLarynx
TracheaCricoidcartilage Lung
Respiratory tube cartilagesin neck and thorax
ThyroidcartilageCartilage in
external earCartilages innose
ArticularCartilageof a jointCostalcartilage
Cartilage inIntervertebraldisc
Pubicsymphysis
Articular cartilageof a joint
Meniscus (padlikecartilage inknee joint)
Copyright © 2010 Pearson Education, Inc. Figure 6.1
Cartilage inexternal ear
Cartilages innose
ArticularCartilageof a jointCostalcartilage
Cartilage inIntervertebraldisc
Pubicsymphysis
Articular cartilageof a joint
Meniscus (padlikecartilage inknee joint)
Copyright © 2010 Pearson Education, Inc. Figure 6.2
Copyright © 2010 Pearson Education, Inc.
Functions of Bones
• Support
• Protection
• Movement
• Storage• Minerals (calcium and phosphorus)
• Blood cell formation in marrow cavities
Copyright © 2010 Pearson Education, Inc. Figure 6.3a-b
Proximalepiphysis
(b)
(a)
Epiphysealline
Articularcartilage
Periosteum
Spongy bone
Compact boneMedullarycavity (linedby endosteum)
Compact bone
Diaphysis
Distalepiphysis
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Membranes of Bone
• Periosteum• Outer fibrous layer
• Inner osteogenic layer
• Osteoblasts (bone-forming cells)
• Osteoclasts (bone-destroying cells)
• Nerve fibers, nutrient blood vessels, and lymphatic vessels enter via nutrient foramina
• Secured to underlying bone by Sharpey’s fibers
Copyright © 2010 Pearson Education, Inc. Figure 6.3c
(c)
Yellowbone marrow
Endosteum
Compact bone
Periosteum
Perforating(Sharpey’s) fibers
Nutrientarteries
Copyright © 2010 Pearson Education, Inc. Figure 6.5
Compactbone
Trabeculae
Spongy bone(diploë)
Copyright © 2010 Pearson Education, Inc. Figure 6.6
Structuresin thecentralcanal
Artery withcapillariesVeinNerve fiber
Lamellae
Collagenfibersrun indifferentdirections
Twistingforce
Copyright © 2010 Pearson Education, Inc. Figure 6.7a-c
Endosteum lining bony canalsand covering trabeculae
Perforating (Volkmann’s) canal
Perforating (Sharpey’s) fibersPeriosteal blood vesselPeriosteum
Lacuna (withosteocyte)
(a)
(b) (c)Lacunae
Lamellae
NerveVeinArteryCanaliculiOsteocytein a lacuna
Circumferentiallamellae
Osteon(Haversian system)
Central(Haversian) canal
Centralcanal
Interstitial lamellae
Lamellae
Compactbone
Spongy bone
Copyright © 2010 Pearson Education, Inc. Figure 6.3b
(b)
Lacunae
Lamellae
Nerve
Vein
Artery
Canaliculus
Osteocytein a lacuna
Centralcanal
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Chemical Composition of Bone
• Organic bone matrix secreted by osteoblasts• Collagen fibers 33%
• Provide tensile strength and flexibility
• Inorganic hydroxyapatites (mineral salts)• 65% of bone by mass
• Mainly calcium phosphate crystals
• Responsible for hardness
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Bone Development
• Osteogenesis (ossification)—bone tissue formation
• Stages• Bone formation—begins in the 2nd month of
development
• Postnatal bone growth—until early adulthood
• Bone remodeling and repair—lifelong
Copyright © 2010 Pearson Education, Inc. Figure 6.10
Calcified cartilagespicule
Osseous tissue(bone) coveringcartilage spicules
Resting zone
Osteoblast depositingbone matrix
Proliferation zoneCartilage cells undergo mitosis.
Hypertrophic zoneOlder cartilage cells enlarge.
Ossification zoneNew bone formation is occurring.
Calcification zoneMatrix becomes calcified; cartilage cells die; matrix begins deteriorating.
1
2
3
4
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Hormonal Regulation of Bone Growth
• Growth hormone stimulates epiphyseal plate activity
• Thyroid hormone modulates activity of growth hormone
• Testosterone and estrogens (at puberty)• Promote adolescent growth spurts
• End growth by inducing epiphyseal plate closure
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Bone Deposit
• Occurs where bone is injured or added strength is needed
• Requires a diet rich in protein; vitamins C, D, and A; calcium; phosphorus; magnesium; and manganese
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Control of Remodeling
•What controls continual remodeling of bone?• Hormonal mechanisms that maintain calcium
homeostasis in the blood
• Mechanical and gravitational forces
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Hormonal Control of Blood Ca2+
• Calcium is necessary for• Transmission of nerve impulses
• Muscle contraction
• Blood coagulation
• Cell division
Copyright © 2010 Pearson Education, Inc. Figure 6.12
Osteoclastsdegrade bonematrix and release Ca2+
into blood.
Parathyroidglands
Thyroidgland
Parathyroidglands releaseparathyroidhormone (PTH).
StimulusFalling bloodCa2+ levels
PTH
Calcium homeostasis of blood: 9–11 mg/100 mlBALANCEBALANCE
Copyright © 2010 Pearson Education, Inc. Table 6.2
Copyright © 2010 Pearson Education, Inc. Table 6.2
Copyright © 2010 Pearson Education, Inc. Table 6.2
Copyright © 2010 Pearson Education, Inc.
Bone Repair
Blood fromruptured bloodvessels forms aclot surroundingthe ends of thebroken bone
1 Healing beginswhen a callus ofcartilage replacesthe clot
2 Bone gradually replaces thecartilage in thecallus
3 When maturebone completelyreplaces the callusand the originalshape of the bonehas been mostlyrestored, thefracture is healed
4
largebloodclotcompact bonespongy bone
