Download chapter 6: the skeletal system

CHAPTER 6:
THE SKELETAL SYSTEM
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SKELETAL CARTILAGE
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Figure 6.1 The bones and cartilages of the human skeleton.
Cartilage in
external ear
Cartilage in
Intervertebral
disc
Cartilages in
nose
Articular
Cartilage
of a joint
Epiglottis
Thyroid
cartilage
Cricoid
cartilage
Larynx
Trachea
Lung
Costal
cartilage
Respiratory tube cartilages
in neck and thorax
Pubic
symphysis
Meniscus
(padlike
cartilage in
knee
joint)
Articular
cartilage
of a joint
Bones of skeleton
Axial skeleton
Appendicular skeleton
Cartilages
Hyaline cartilages
Elastic cartilages
Fibrocartilages
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GROWTH OF CARTILAGE
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Intervertebral discs are made of which type
of cartilage?
1) Elastic cartilage
2) Fibrocartilage
3) Hyaline cartilage
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BONE CLASSIFICATION
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AXIAL VS. APPENDICULAR
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Figure 6.1 The bones and cartilages of the human skeleton.
Cartilage in
external ear
Cartilage in
Intervertebral
disc
Cartilages in
nose
Articular
Cartilage
of a joint
Epiglottis
Thyroid
cartilage
Cricoid
cartilage
Larynx
Trachea
Lung
Costal
cartilage
Respiratory tube cartilages
in neck and thorax
Pubic
symphysis
Meniscus
(padlike
cartilage in
knee
joint)
Articular
cartilage
of a joint
Bones of skeleton
Axial skeleton
Appendicular skeleton
Cartilages
Hyaline cartilages
Elastic cartilages
Fibrocartilages
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Figure 6.2 Classification of bones on the basis of shape.
(a) Long bone
(humerus)
(b) Irregular bone
(vertebra), right
lateral view
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(c) Flat bone
(sternum)
(d) Short bone
(talus)
FUNCTIONS OF BONES
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True or false: Every bone has the same
primary functions.
1) True
2) False
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BONE STRUCTURE
GROSS STRUCTURE
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Figure 6.3 The structure of a long bone (humerus of arm).
Articular
cartilage
Proximal
epiphysis
Compact bone
Spongy bone
Epiphyseal
line
Periosteum
Compact bone
Medullary
cavity (lined
by endosteum)
Diaphysis
Endosteum
(b)
Yellow
bone marrow
Compact bone
Periosteum
Perforating
(Sharpey’s)
fibers
Nutrient
arteries
Distal
epiphysis
(a)
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(c)
Figure 6.5 Flat bones consist of a layer of spongy bone sandwiched between two thin layers of compact bone.
Spongy bone
(diploë)
Compact
bone
Trabeculae
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The connective tissue surrounding a bone
is called the…
1)
2)
3)
4)
Diaphysis
Endosteum
Epiphysium
Periosteum
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True or false: Trabeculae are found in
compact bone.
1) True
2) False
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BONE STRUCTURE
MICROSCOPIC ANATOMY
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Figure 6.4 Comparison of different types of bone cells.
(a) Osteogenic cell
(b) Osteoblast
(c) Osteocyte
(d) Osteoclast
Stem cell
Matrix-synthesizing
cell responsible
for bone growth
Mature bone cell
that maintains the
bone matrix
Bone-resorbing cell
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Figure 6.6 A single osteon.
Structures
in the
central
canal
Artery with
capillaries
Vein
Nerve fiber
Lamellae
Collagen
fibers
run in
different
directions
Twisting
force
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Figure 6.7 Microscopic anatomy of compact bone.
Spongy bone
Compact
bone
Central
(Haversian) canal
Perforating
(Volkmann’s) canal
Endosteum lining bony canals
and covering trabeculae
Osteon
(Haversian system)
Circumferential
lamellae
(a)
Perforating (Sharpey’s) fibers
Lamellae
Nerve
Vein
Artery
Canaliculi
Osteocyte
in a lacuna
(b)
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Periosteal blood vessel
Periosteum
Lamellae
Central
canal
Lacunae
Lacuna (with
osteocyte)
(c)
Interstitial lamellae
The cells which build new bone are:
1)
2)
3)
4)
Osteoblasts
Osteogenic cells
Osteoclasts
Osteocytes
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Osteocytes receive their nutrition from fluid in
the ________, which are connected to
the larger ___________.
1) Canaliculi / central canal
2) Lamellae / lacunae
3) Osteoblasts / lacunae
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BONE STRUCTURE
CHEMICAL COMPOSITION OF BONE
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Hydroxyapatite is part of the _______
component of bone.
1) Cellular
2) Organic
3) Inorganic
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OSTEOGENESIS
INTRAMEMBRANOUS OSSIFICATION
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Figure 6.8 Intramembranous ossification.
Mesenchymal
cell
Collagen
fiber
Ossification
center
Osteoid
Osteoblast
Osteoid
Osteocyte
Newly calcified
bone matrix
Osteoblast
1 Ossification centers appear in the fibrous
connective tissue membrane.
• Selected centrally located mesenchymal cells cluster
and differentiate into osteoblasts, forming an
ossification center.
Mesenchyme
condensing
to form the
periosteum
Trabeculae of
woven bone
Blood vessel
2 Bone matrix (osteoid) is secreted within the
fibrous membrane and calcifies.
• Osteoblasts begin to secrete osteoid, which is calcified
within a few days.
• Trapped osteoblasts become osteocytes.
Fibrous
periosteum
Osteoblast
Plate of
compact bone
Diploë (spongy
bone) cavities
contain red
marrow
4 Lamellar bone replaces woven bone, just deep to
3 Woven bone and periosteum form.
the periosteum. Red marrow appears.
• Accumulating osteoid is laid down between embryonic
blood vessels in a random manner. The result is a network • Trabeculae just deep to the periosteum thicken, and are later
replaced with mature lamellar bone, forming compact bone
(instead of lamellae) of trabeculae called woven bone.
• Vascularized mesenchyme condenses on the external face plates.
• Spongy bone (diploë), consisting of distinct trabeculae, perof the woven bone and becomes the periosteum.
sists internally and its vascular tissue becomes red marrow.
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OSTEOGENESIS
ENDOCHONDRIAL OSSIFICATION
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Figure 6.9 Endochondral ossification in a long bone.
Month 3
Week 9
Birth
Childhood to
adolescence
Articular
cartilage
Secondary
ossification
center
Epiphyseal
blood vessel
Area of
deteriorating
cartilage matrix
Hyaline
cartilage
1 Bone collar
Epiphyseal
plate
cartilage
Spongy
bone
formation
Bone
collar
Primary
ossification
center
Medullary
cavity
Blood
vessel of
periosteal
bud
2 Cartilage in the
3 The periosteal
center of the
forms around
hyaline cartilage diaphysis calcifies
and then develops
model.
cavities.
bud invades the
internal cavities
and spongy bone
begins to form.
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Spongy
bone
4 The diaphysis elongates
and a medullary cavity
forms as ossification
continues. Secondary
ossification centers appear
in the epiphyses in
preparation for stage 5.
5 The epiphyses
ossify. When
completed, hyaline
cartilage remains only
in the epiphyseal
plates and articular
cartilages.
The starting point for endochondrial
ossification is called the…
1)
2)
3)
4)
Medullary cavity
Periosteal bud
Primary ossification center
Bone collar
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POSTNATAL BONE GROWTH
AND REMODELING
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Figure 6.10 Growth in length of a long bone occurs at the epiphyseal plate.
Resting zone
1 Proliferation zone
Cartilage cells undergo
mitosis.
2 Hypertrophic zone
Older cartilage cells
enlarge.
Calcified cartilage
spicule
Osteoblast depositing
bone matrix
Osseous tissue
(bone) covering
cartilage spicules
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Calcification zone
Matrix becomes calcified;
cartilage cells die; matrix
begins deteriorating.
3
Ossification zone
New bone formation is
occurring.
4
Figure 6.11 Long bone growth and remodeling during youth.
Bone growth
Cartilage
grows here.
Bone remodeling
Articular cartilage
Epiphyseal plate
Cartilage
is replaced
by bone here.
Cartilage
grows here.
Cartilage
is replaced
by bone here.
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Bone is
resorbed here.
Bone is added
by appositional
growth here.
Bone is
resorbed here.
Growth of bone length is due largely to
increasing numbers of cells in
the _______ zone…
1)
2)
3)
4)
calcification
hypertrophic
ossification
proliferation
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CONTROL OF BONE REMODELING
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Figure 6.12 Parathyroid hormone (PTH) control of blood calcium levels.
Calcium homeostasis of blood: 9–11 mg/100 ml
BALANCE
BALANCE
Stimulus
Falling blood
Ca2+ levels
Thyroid
gland
Osteoclasts
degrade bone
matrix and
release Ca2+
into blood.
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Parathyroid
glands
PTH
Parathyroid
glands release
parathyroid
hormone (PTH).
Figure 6.13 Bone anatomy and bending stress.
Load here (body weight)
Head of
femur
Tension
here
Compression
here
Point of
no stress
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Which of the following does NOT control
bone growth or remodeling?
1)
2)
3)
4)
5)
Growth hormone
Mechanical force
Parathyroid hormone
Thyroid hormone
Calcitonin
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FRACTURES
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Table 6.2 Common Types of Fractures (1 of 3)
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Table 6.2 Common Types of Fractures (2 of 3)
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Table 6.2 Common Types of Fractures (3 of 3)
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The type of fracture which commonly occurs in
porous bones subjected to a fall is a…
1)
2)
3)
4)
5)
6)
Comminuted fracture
Compression fracture
Spiral fracture
Epiphyseal fracture
Depression fracture
Greenstick fracture
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BONE REPAIR
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Figure 6.15 Stages in the healing of a bone fracture.
Hematoma
Internal
callus
(fibrous
tissue and
cartilage)
1 A hematoma forms.
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External
callus
New
blood
vessels
Bony
callus of
spongy
bone
Healed
fracture
Spongy
bone
trabecula
2 Fibrocartilaginous
callus forms.
3 Bony callus forms.
4 Bone
remodeling
occurs.
True or false: if a bone breaks, it bleeds.
1) True
2) False
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HOMEOSTATIC IMBALANCES
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Figure 6.16 The contrasting architecture of normal versus osteporotic bone.
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The disease which causes children to have
soft, malformed bones due to vitamin D or
calcium deficiency is…
1) Rickets
2) Osteomalacia
3) Osteporosis
4) Paget’s Disease
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FETAL SKELETAL DEVELOPMENT
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Figure 6.17 Fetal primary ossification centers at 12 weeks.
Parietal bone
Occipital bone
Mandible
Frontal bone
of skull
Clavicle
Scapula
Radius
Ulna
Ribs
Humerus
Vertebra
Ilium
Tibia
Femur
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