How does Vitamin D promote bone growth? Is it a negative feedback loop?

[lull]

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Kaplan is confusing me on this. I understand that Vitamin D promotes bone resorption to increases calcium and phosphate in the blood. Is it the consequential increase in these ions that promote Calcitonin activation that ultimately results in bone growth?

 

[Gambino.]

Vitamin D has active forms called calcitriol and cholecalciferol which increase GI absorption of calcium from your diet. Calcitonin is a product of parafollicular C cells that is stimulated by gastrin or elevated plasma calcium which causes inhibition of osteoclast mediated bone absorption, ultimately decreasing serum calcium. So essentially its calcium induced calcium release until it's too high at which point calcitonin comes into the equation.

Idk if I answered your question but this is essentially the detail we learned it in 1st semester.