Calcium and Bones

Calcium and Bones - to stimulate the intestine to absorb...

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Calcium and Bones The mineral component of bones is produced by the activity of osteoblasts. Mineralization is a crystallization process in which ions (calcium, phosphate, bicarbonate and others) are removed from blood plasma and deposited in bone tissue. When new bone is formed, a network of collagen fibers are produced by the osteoblasts; these fibers become encrusted with minerals (hydroxyapatite and calcium carbonate). The skeletal system, while important for protective and structural reasons, was probably originally designed as a place to store calcium and other ions for use later. Calcitriol Calcitriol is produced in response to the UV radiation penetrating the epidermal keratinocytes. It can also be ingested. Either way, it is processed by the liver and kidney and enters the blood
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Unformatted text preview: to stimulate the intestine to absorb calcium, phosphate and magnesium. Calcitriol also weakly promotes urinary reabsorption of calcium ions. Significantly, calcitriol also promotes osteoclast activity, raising blood calcium levels. Calcitonin Calcitonin is secreted by special cells of the thyroid gland when calcium blood concentration rises too high. It reduces osteoclast activity by as much as 70% in 15 minutes and increases the number and activity of osteoblasts. Parathyroid Parathyroid hormone is secreted by the parathyroid glands when calcium blood levels are too low. It stimulates osteoclast production and activity, promotes calcium resorption by the kidneys, calcitriol synthesis in the kidneys, and inhibits collagen synthesis and bone deposition by osteoblasts....
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This note was uploaded on 01/30/2012 for the course BSC BSC1085 taught by Professor Sharonsimpson during the Fall '10 term at Broward College.

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