How Does the Body Respond to Calcium Levels Greater Than

question 10

Multiple Choice

How does the body respond to calcium levels greater than 10.5 mg/dL?

• A) When the plasma calcium level reaches 10.5 mg/dL, calcitonin is secreted, which lowers the level of circulating calcium by antagonizing the effect of parathormone (PTH) on bone.
• B) When the plasma calcium level reaches 10.5 mg/dL, calcitonin is secreted, which raises the level of circulating calcium by potentiating the effect of PTH on bone.
• C) When the plasma calcium level reaches 10.5 mg/dL, PTH is secreted, which lowers the level of circulating calcium by antagonizing the effect of calcitonin on bone.
• D) None of these are correct. When the plasma calcium level becomes too high (hypercalcemia, more than 10.5 mg/dL), calcitonin is secreted. It lowers the circulating calcium level by antagonizing the effect of PTH on bone. Calcitonin directly inhibits bone resorption so that calcium ions are retained in the bone. This is particularly important in children during bone development. It does not affect intestinal and renal calcium absorption, and its action does not require vitamin

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