Download Skeletal System: Bones and Bone Tissue

Anatomy and Physiology
Chapter 6
Skeletal System:
Bones and Bone Tissue
Skeletal System Functions
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Support
Protection
Movement
Storage
Blood cell production
Hyaline Cartilage
• Consists of specialized
cells that produce
matrix
• Cells
– Chondroblasts
– Chondrocytes
• Perichondrium
• Articular cartilage
• Growth
– Appositional
– Interstitial
Bone Shapes
• Long
– Upper and lower limbs
• Short
– Carpals and tarsals
• Flat
– Ribs, sternum, skull,
scapulae
• Irregular
– Vertebrae, facial
Long Bone Structure
• Diaphysis
– Shaft
– Compact bone
• Epiphysis
– End of the bone
– Cancellous bone
• Epiphyseal plate
– Growth plate
• Epiphyseal line
– Bone stops growing in
length
Long Bone Structure
• Medullary cavity
– Red marrow
– Yellow marrow
• Periosteum
– Outer bone surface
• Sharpey’s fibers
– Attachment
• Endosteum
– Lines bone cavities
Flat, Short, Irregular Bones
• Flat Bones
– No diaphyses, epiphyses
– Sandwich of cancellous
between compact bone
• Short and Irregular Bone
– Compact bone that
surrounds cancellous
bone center
– No diaphyses and not
elongated
Bone Histology
• Bone matrix
– Organic: Collagen and proteoglycans
– Inorganic: Hydroxapatite
• Bone cells
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Osteoblasts
Osteocytes
Osteoclasts
Stem cells or osteochondral progenitor cells
Woven bone: Collagen fibers randomly oriented
Lamellar bone: Mature bone in sheets
Cancellous bone: Trabeculae
Compact bone: Dense
Bone Matrix
Bone Cells
• Osteoblasts
– Formation of bone
through ossification or
osteogenesis
• Osteocytes
– Mature bone cells
– Lacunae: Spaces
– Canaliculi: Canals
• Osteoclasts
– Responsible for bone
resorption
Woven and Lamellar Bone
• Woven bone
– Formed
• During fetal development
• During fracture repair
• Remodeling
– Removing old bone and adding new
• Lamellar bone
– Mature bone in sheets called lamellae
Cancellous Bone
• Consists of trabeculae
– Oriented along lines of
stress
Compact Bone
• Central or haversian canals: Parallel to long axis
• Lamellae: Concentric, circumferential, interstitial
• Osteon or haversian system: Central canal, contents, associated
concentric lamellae and osteocytes
• Perforating or Volkmann’s canal: Perpendicular to long axis
Bone Development
• Intramembranous ossification
– Takes place in connective tissue membrane
• Endochondral ossification
– Takes place in cartilage
• Both methods of ossification
– Produce woven bone that is then remodeled
– After remodeling, formation cannot be
distinguished as one or other
Intramembranous Ossification
Endochondral Ossification
Endochondral Ossification
Endochondral Ossification
Growth in Bone Length
• Appositional growth
– New bone on old bone
or cartilage surface
• Epiphyseal plate zones
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Resting cartilage
Proliferation
Hypertrophy
Calcification
Growth in Bone Length
Growth in Bone Width
Factors Affecting Bone Growth
• Nutrition
– Vitamin D
• Necessary for absorption of calcium from intestines
• Insufficient causes rickets and osteomalacia
– Vitamin C
• Necessary for collagen synthesis by osteoblasts
• Deficiency results in scurvy
• Hormones
– Growth hormone from anterior pituitary
– Thyroid hormone required for growth of all tissues
– Sex hormones as estrogen and testosterone
Bone Remodeling
• Coverts woven bone into lamellar bone
• Bone constantly removed by osteoclasts and new
bone formed by osteoblasts
Bone Repair
Calcium Homeostasis
Calcium Homeostasis
• Bone is the major storage site for calcium in
the body
– Calcium moves into bone as osteoblasts build
new bone
– Calcium moves out of bone as osteoclasts break
down bone
– When osteoclast and osteoblast activity is
balanced, the movement of calcium in and out
is equal
Effects of Aging on
Skeletal System
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Bone Matrix decreases
Bone Mass decreases
Increased bone fractures
Bone loss causes deformity, loss of height,
pain, stiffness
– Stooped posture
– Loss of teeth
Bone Fractures