LIFESCI 2N03 Lecture Notes - Lecture 12: Rickets, Melatonin, Muscle Biopsy
10 Nov 2017
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Document Summary
Reduced bone mineral density (bmd) and microarchitecture deterioration leading to bone fragility. Hip fracture is the worst type of fracture. Resulting in fragility and risk of fracture. 1sd (standard density) decrease in bmd at any site = an increase in fracture risk by 50% Blood calcium is regulated in part by vitamin d and two hormones - calcitonin and parathyroid hormone. Bone serves as a reservoir when blood calcium is high and as a source of calcium when blood calcium is low. Osteoclasts break down bone and release calcium into the blood. Osteoblasts build new bone using calcium from the blood. The active growth phase occurs from birth to approximately age 20. The next phase of peak bone mass development occur between the ages of 12 and 30. The final phase, when bone resorption exceeds formation, begins between the ages of. 30 and 40 and continues through the remainder of life.
