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22 Cards in this Set
- Front
- Back
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Normal mature bone is of what type?
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Lamellar
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What is the dehning characteristic of lamellar bone?
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Remodeled along lines of stress
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What are the two subtypes of lamellar bone?
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Cortical
Cancellous |
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ln contrast, immature or pathologic bone is of what type?
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Woven
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Bone is strongest in what direction? Weakest in what direction?
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Strongest in compression
Weakest in shear |
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When bone is under torsion, where is the greatest load experienced?
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Maximum load experienced at 45 degrees to the long axis of the bone
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What is the basic premise of Wolffs law?
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Increased stress leads to increased bone formation
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Piezoelectric charges: is compression electropositive or negative?
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Compression results in a negative charge
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The negative charge then leads to what process?
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Bone formation
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ls tension electropositive or negative?
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Positive charge
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What does the positive charge lead to?
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Bone resorption
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What is the Heuter-Volkmann law? Give an example of where this law applies.
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Compression inhibits growth
Tension stimulates growth Example: scoliosis |
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At what age is peak bone mass achieved?
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End of the third decade of life (the 20s)
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What is the annual rate of bone loss after peak?
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0.3 to 0.5% per year
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What is the annual rate of bone loss after menopause, without treatment?
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2 to 3% per year for 6 to 10 years after menopause
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ls the observed postmenopausal decline simply estrogen related?
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Not just estrogen, but changes in calcium metabolism also
Decreased intestinal calcium absorption Increased calcium losses |
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ls the nutrient system high or low pressure?
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High pressure
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What does it supply?
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Inner two thirds of bone
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ls the periosteal system high or low pressure?
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Low pressure
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What does it supply?
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Outer one third of bone
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ln what direction does blood flow in the adult?
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Nutrient to periosteal
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In what direction does blood flow in immature bone?
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Opposite direction of flow
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