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钙是人体必需的常量元素之一。它在体内含量排在第五位,是身体中最多的一种阳离子。成人体内的钙总量约为1000-1200克,其中99%集中在骨骼和牙齿,存在形式主要是羟磷灰石。其中1%的钙常以游离或结合的离子状态存在于软组织、细胞外液及血液中,统称为混溶钙池。混溶钙池与骨骼中的钙维持着动态平衡,即骨骼中钙不断地从破骨细胞中释出进入混溶钙池;而混溶钙池中的钙又不断地沉积于骨细胞中,从而使骨骼得以不断更新。这种钙的更新,成人每日约700毫克。钙的更新率随年龄的增长而减慢。幼儿的骨骼每1-2年更新1次,成人更新1次需10-12年。
Calcium is one of the necessary constant elements of the body. It ranks fifth in the body and is the largest of the cations in the body. The total amount of calcium in adults is about 1000-1200 grams, of which 99% concentrated in the bones and teeth, the main form of existence is hydroxyapatite. Of which 1% of the calcium often free or combined ion present in the soft tissue, extracellular fluid and blood, collectively referred to as mixed calcium pool. Mixed calcium pool and bone in the calcium to maintain a dynamic balance, that is, bone calcium continuously released from the osteoclasts into the mixed calcium pool; and mixed calcium pool of calcium and continue to deposit in the bone cells, So bones can be constantly updated. This calcium update is about 700 mg daily for adults. The update rate of calcium slows with age. Children’s bones every 1 - 2 years to update 1, adult updates 1 need 10-12 years.