What is one way that calcitonin and parathyroid hormone maintain homeostasis? A. Calcitonin stimulates the bones to excrete calcium when calcium levels are too high, while parathyroid hormone stimulates the bones to absorb calcium when calcium levels are too low. B. Calcitonin stimulates the kidneys to excrete calcium when calcium levels are too high, while parathyroid hormone stimulates the kidneys to absorb calcium when calcium levels are too low. C. Calcitonin stimulates the bones to absorb calcium when calcium levels are too low, while parathyroid hormone stimulates the bones to excrete calcium when calcium levels are too high. D. Calcitonin stimulates the kidneys to absorb calcium when calcium levels are too low, while parathyroid hormone stimulates the kidneys to excrete calcium when calcium levels are too high.

B

Explanation:

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The most appropriate answer would be option B.

The calcitonin and parathyroid hormone (PTH) are involved in the homeostasis of blood calcium levels.

The calcitonin is released from thyroid gland when the blood calcium levels are above normal range.

It is mainly involved in lowering the blood calcium levels to the normal range. It does so by inhibiting the activity of osteoclast in the bones and thus, reduces the release of bone calcium in the blood. In addition, it reduces or inhibits the reabsorption of the calcium and phosphate ions in the renal tubular cells.

The PTH is released from parathyroid gland when blood calcium levels are lower than normal.

In contrast to calcitonin, the PTH increases the blood calcium levels to the normal levels. It increases the activity of osteoclast in bones and increases the reabsorption of calcium and phosphate in the renal tubular cells.