Bone remodeling

Question 1

Describe the process and purpose of bone remodeling – give an example of when it might occur, and be sure to tie osteoblastic and osteoclastic activity back into the bone remodeling

Answer 1

In bone remodeling, osteocytes must sense an increase or decrease in strain. Decreased strain leads to higher osteoclast activity to remove underloaded bone tissue. An example is when astronauts go into space as low gravity leads to less activity, leading to loss of bone tissue. Increased strain leads to higher osteoblast activity to build more bone in more heavily loaded areas. An example is athletes as they are constantly active and moving their bodies.

Question 2

As a “step-back” overview, give 4 examples of when a bone is modeled/remodeled.

Answer 2

Braces, learning to walk, learning new movement patterns, learning a new sport

Question 3

Discuss the molecules that control bone formation, and how they modulate bone formation. Separate them into hormones and vitamins, paying attention to which stimulate osteoclasts, which inhibit osteoclasts, which stimulate osteoblasts, and which contribute to bone formation & health via other means.

Answer 3

Stimulates osteoblasts: estrogen, testosterone, thyroid hormone, human growth hormone, insulin-like growth factors
Stimulate osteoclasts: parathyroid hormones
Inhibits osteoclasts: calcitonin
Stimulates bone function by other methods: Vitamin A, C, D, Vitamin B12, Insulin, Vitamin K