2. Skeletal Cartilages
• The skeletal cartilages are surrounded by a
dense irregular connective tissue called the
perichondrium.
– Supplies nutrients & removes wastes from
cartilage through diffusion from a rich
vasculature
• Three types
– Hyaline cartilage
– Elastic cartilage
– Fibrocartilage
• Chondrocytes located within lacunae. 2
6. Functions of Bones
• Support
• Protection
• Movement
• Mineral storage
• Blood cell formation
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7. Long Bone Structure
• Diaphysis – shaft
– Compact bone surrounded by periosteum & endosteum
• osteoblasts and osteoclasts
– Central medullary cavity
• in adults: filled with yellow bone marrow – fat storage
• Epiphyses – ends – proximal and distal
– Spongy bone
– Hyaline cartilage at articulations
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9. Structure of Other Bone Shapes
Short, irregular, and flat bones
– Periosteum and endosteum
– Dense bone on outer part
– Spongy bone in middle part
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10. Hematopoietic Tissues
• Red bone marrow
– In adults red bone marrow is found in the spongy
bone of the femur, humerus, sternum, and pelvic
girdle (hip bone)
– In infants, red bone marrow is found in all the
bones.
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11. Microscopic Structure of Bone:
Compact (Dense) Bone
The osteons are the structural units of dense bone (formerly
known as Haversian systems).
– Columns that run parallel to long axis of the bone.
– Each is ringed like a tree.
• A lamella is an individual ring.
• A lacuna is a space found between the lamellae.
• Osteocytes are the cells that occupy the lacunae.
The osteon is traversed by canals for blood vessels and nerves.
Central (Haversian) canal runs down the center of the osteon
Perforating (Volkman) canal runs perpendicular to the osteon
Canaliculi connect the lacunae.
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13. Chemical Composition of Bone
• 35% of bone is organic
– Osteocytes, osteoblasts, osteoclasts.
– Ground substance and collagen fibers.
• 65% of bone is inorganic
– Calcium phosphate
• Also known as Hydroxyapatites
• The minerals form small crystals around the
collagen fibers
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14. Types of Fractures
Comminuted fracture – bone breaks into 3 or more pieces
Compression fracture – bone is crushed
Spiral fracture – ragged break in bone due to twisting
Epiphyseal fracture – epiphysis separates from diaphysis
Depressed fracture – skull fractures inward
Greenstick fracture – only one side of bone breaks; the other
side bends. Common in children.
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15. Repair of Fractures: 4 steps
– Hematoma formation – mass of clotted blood
– Callus formation – “soft callus” (cartilaginous) splint
– Bony callus formation – “hard callus” (spongy bone)
– Bone remodeling – remove spongy bone of hard
callus, replace with compact bone
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16. Homeostatic Imbalances of Bone
• Osteomalacia
– Inadequate bone mineralization
– Pain with stress on bones
– Known as Rickets in children
– Due to insufficient calcium leading to inadequate
mineralization in youth.
– Bowed bones and improper formation.
– Vitamin D deficiency
• Osteoporosis
– Over activity of osteoclasts.
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18. A condition that produces a reduction in
bone mass sufficient to compromise
normal function is
B. osteopenia.
C. osteoporosis.
D. osteitis.
E. osteomyelitis.
F. osteomalacia.
19. A major difference between bone tissue and other
connective tissues lies in which of the following?
C. The limited blood supply available to bone
tissue
D. The inability of bone cells to metabolize nutrients
for energy
E. The presence of collagen fibers in bone
F. The presence of elastic fibers in bone
G. The composition of the intercellular substance of
bone
20. How would increasing the proportion of
organic molecules to inorganic
components in the bony matrix affect the
physical characteristics of bone?
B. The bones would be stronger.
C. The bones would be more brittle.
D. The bones would be more flexible.
E. The bone would be less flexible.
F. The bones would be less compressible.
21. Long bones differ from flat bones in that
long bones
B. have an outer layer of compact bone.
C. have epiphyses.
D. contain marrow.
E. have a periosteum membrane.
F. contain spongy bone.
22. The bones of the skeleton store energy
reserves as lipids in areas of
B. yellow marrow.
C. red marrow.
D. the ground substance.
E. spongy bone.
F. the matrix of bone tissue.
23. The cells that maintain mature compact
bone are
B. osteocytes.
C. lacunae.
D. osteoclasts.
E. chondrocytes.
F. osteoblasts.
24. The lacunae of bone contain
B. blood cells.
C. osteons.
D. chondroblasts.
E. bone marrow.
F. osteocytes.
25. A fracture in the shaft of a bone would occur
in the
B. metaphysis.
C. epiphysis.
D. diaphysis.
E. epiphyseal line.
26. Osteocytes maintain contact with the blood
vessels of the central canal through
B. periosteum.
C. canaliculi.
D. drainage canals.
E. concentric lamellae.
27. Spongy bone contains all of the following
except
B. true osteons.
C. collagen fibers.
D. hydroxy apatite.
E. trabeculae.
28. Collagen in the bone matrix provides flexible
strength.
True
False
