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45 Cards in this Set

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What are the two portions of the bone matrix?
1. Inorganic (calcified) portion
2. Organic portion
What does the inorganic (calcified) portion primarily contain?
Hydroxyapattite crystals
What does the organic portion primarily contain?
1. Type I collagen
2. Ground Substance
T/F - Periosteum is calcified.
False - it is non calcified
What are the two layers of the periosteum?
1. Outer fibrous collagenous layer.
2. Inner cellular (ostrogenic) layer
What provides for the osteoprogenitors?
Periosteum
What type of fibers can be seen in periosteum?
Sharpey's fiber
What supplies blood vessels to bone?
Periosteum
What is the endosteum?
Similar to periosteum, but lines bone marrow.
List the four types of bone cells.
1. Osteogenitor cells
2. Osteoblasts
3. Osteoclasts
4. Osteocytes
What is osteoprogenitor derived from?
Embryonic mesenchyme
Where are osteoprogenitors located in?
Periosteum and endosteum
What are osteoblasts derived from?
Osteoprogenitors
What is an osteoid and what cell is responsible for synthesis and secretion?
Uncalcified bone matrix

Osteoblasts
Osteocytes are derived from what cell?
Osteoblasts
How do osteocytes maintain communications?
Via gap junctions
Describe the cytoplasmic processes of osteocytes.
Narrow cytoplasmic processes extend through canaliculi in the calcified matrix.
Osteoclasts are derived from what cell?
Monocytes
What is Howship's lacunae and what is in them?
Area of bone resorption

Osteoclasts
Describe the morphology of osteoclasts.
Large, motile, multinucleated cells with ruffled border and clear zone.
How do osteoclasts participate in bone resorption? x3
1. Secrete acid to create acidic environment (dissolving CaPO4)
2. Secrete enzymes to digest collagen proteins
3. Resorbs the residue of the bone matrix
1. Concentric Lamellae
2. Osteon
3. Canaliculi
4. Haversion canal
5. Lacuna
6. Haversion canal
7. Volksman's canal
8. Sharpey's fibers
9. Periosteum
10. Blood vessels
11. Outer circumferential lamellae
12. Inner circumferential lamellae
13. Compact bone
14. Cancellous bone
Answer
Describe what Haversion systems (AKA - osteons) are.
Long cylinders running parallel to long axis of bone

Composed of 4 to 20 lamellae surrounding Haversion canal.
What do Volkman's canals do?
Interconect Haversion canals
What is interstitial lamellae?
Little strips of lamellated bone
Outer/Inner Circumferential lamellae

- where is it?
- what does it do?
Circumnavigates entire bone

Makes it stronger
Primary center of ossification:

- Develops where?
- AKA
At the midriff of the DIAPHYSIS of hyaline cartilage bone model

Primary bone formation
Steps in Primary center of ossification.
1. Perichondrium vascularization
2. Subperiosteal bone collar formation
3. Degeneration of chondrocytes
4. Osteoclasts perforate the bone collar
5. Creation of calcified cartilage/calcified bone complex
6. Collar thickens and marrow widens
Compare and contrast Secondary Center of Ossification with Primary Center of Ossification.
Sequence is similar

but occurs at epiphysis

When epiphysis is filled with bone tissue,

cartilage

remains at articular surface
and
remains as an epiphyseal plate
List the zones of the epiphyseal plate and characters of each.
Zone of Reserve
(Inactive chondrocytes)

Zone of Proliferation
(Mitotically active chondrocytes)

Zone of Hypertrophy/Maturation
(Enlarged chondrocytes)

Zone of Calcification
(Chondrocyte death & calcified matrix)

Zone of Ossification
(Bone elaboration, followed by resorption)
Intramembranous bone formation:

- main difference from endochondral bone formation
- List the events
No pre-existing cartilage

1. Mesenchymal cells differentiate into osteoblasts.
2. Osteoid calcifies trapping osteoblasts.
3. Fusion of trabeculae produces cancellous bone
4. Periosteum & Endosteum develop
Bone repair:

- Begins with proliferation of what?
- Formation of what?
- What happens as fracture heals?
Osteoprogenitors

Bony callus

Primary bone replaced by secondary bone
Define Synarthroses
Immovable joint
Define Diarthroses (synovial joints)
Joints permitting maximum movement
Vitamin A deficiency can lead to what? Give example.
Inhibits proper bone formation.

Remodeling of cranial fault fails to accommodate brain, leading to serious CNS damage
Hypervitaminosis A can lead to what? Give example
Accelerated ossification of epiphyseal plate.

Premature ceasing of growth
Vitamin C deficiency causes what? Give example
Connective tissue unable to produce and maintain ECM.

Retarded growth and delayed healing
Scurvy is caused by what?
Vitamin C deficiency
Vitamin D deficiency causes what disease:

- in children
- in adults
Rickets

Osteomalacia
Vitamin D is necessary for what? x2
Calcium absorption in GI

Bone formation
Vitamin D deficiency will cause what?
Poorly calcified bones deformed by weight bearing.
Parathyroid Hormone:

- Effect on cell
- Effect on electrolyte
- Excess leads to what?
Activates osteoclasts

Increases blood calcium

Weakens bone
Calcitonin:

- Effect on cell
- Effect on electrolyte
Inhibits osteoclasts

Decreases blood calcium
Pituitary Growth Hormone:

- does what?
- excess leads to what?
Stimulates overall growth at the epiphyseal plates

Acromegaly and Giantism
Calcium deficiency can cause what?
Osteomalacia in adults

Rickets in Children