Bone Remodeling

Bone Remodeling
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Homeostasis process- regulates Ca in the blood
• involves bone formation and destruction
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Controlled by hormonal and mechanical factors.
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Occurs constantly with every bone in the body.

Bone Remodeling
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Bone formation is called “bone depositing”.
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Bone destruction is called “bone resorption”.

Bone Remodeling
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Hormonal Factors affecting bone deposit and resorption:
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Are governed by negative feedback control systems.
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Depend upon blood levels of calcium.

Bone Depositing
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When Calcium blood levels rise above normal:
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Detected by the Thyroid (control center)
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Response: Releases the hormone calcitonin
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Signals the osteoblasts to undergo bone depositing (builds bone)
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Effect: Calcium blood levels drop & Thyroid stops producing calcitonin

BONE REMODELING CYCLE

Bone Remodeling
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When Calcium blood levels fall below normal:
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Detected by the Parathyroid (control center)
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Response: Releases parathyroid hormone (PTH)
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Signals the osteoclasts to perform Bone resorption
(breaks down bone)
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Effect: Calcium blood levels rise & Parathyroid stops producing PTH

BONE REMODELING CYCLE

Bone Remodeling
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Mechanical Factors can also stimulate this process:
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Weight bearing exercises put stress on the bone
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The stress releases signals to build bone in order to withstand that stress, making bone stronger
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Used in physical therapy for disorders in weak bone (such as osteoporosis)

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OVERVIEW:
Homeostatic process that regulates ____________________________ by
_______________________________ and ___________________________ bone
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Regulated by what two factors:
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Occurs in what circumstances:
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Bone formation is called:
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Bone destruction is called:
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When regulated by hormones, what type of feedback
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What is monitored to determine hormone release?
HOW MECHANICAL FACTORS INFLUENCE BONE REMODELING:

BONE DEPOSITING:
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Control center:
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Trigger/stimulus:
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Hormone:
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Effect of hormone (what does it talk to?):
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Result:
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How does the mechanism end?
Draw a diagram below:

BONE RESORPTION:
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Control center:
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Trigger/stimulus:
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Hormone:
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Effect of hormone (what does it talk to?):
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Result:
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How does the mechanism end?
Draw a diagram below: