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Bone Remodeling. Bone Remodeling. Bones are remodeled continually Means that they are broken down, built back up, change in shape, etc Bone remodeling is in response to 2 factors: Calcium levels in the blood The pull of gravity and muscles. Bone Remodeling: Calcium Levels.
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Bone Remodeling • Bones are remodeled continually • Means that they are broken down, built back up, change in shape, etc • Bone remodeling is in response to 2 factors: • Calcium levels in the blood • The pull of gravity and muscles
Bone Remodeling: Calcium Levels • When calcium levels drop below homeostatic levels, your parathyroid gland releases parathyroid hormone (PTH) • This stimulates osteoclasts to break down bone to release calcium in the blood • When calcium levels are too high, calcium is deposited in the bone • This is how bones are storage organs!!
Bone Remodeling: Gravity and Muscles • The more weight-bearing exercises you do, the stronger your bones will be • This causes an increase in bone size • Bedridden patients and astronauts suffer from bone mass/atrophy from lack of stress on their bones
Balance • There is a balance between osteoclasts and osteoblasts • Predict: • What would happen if the osteoblasts were too good at their job? • Melorheostosis (remember this??) • What would happen if the osteoclasts were too good at their job?
Gorham’s Disease • “Vanishing Bone Disease” • Osteoclasts are overproductive and bones are broken down faster than they are built • http://www.youtube.com/watch?v=lHN3Qwbm86Q