Blood calcium is regulated by a hormonal control system. normal blood calcium levels are 8.5 to 11 mg/dl. when calcium levels are too high, the thyroid detects this and releases calcitonin. calcitonin stimulates the kidneys to release more calcium and it causes bones to absorb more calcium and build more matrix. identify the elements of this control system by matching the items below. some answers will not be used and some may be used more than once.

FEEDBACK MECHANISM is a regulatory mechanism in which presence of certain level of substance promotes or inhibits its further formation.
The regulation of secretion of Thyrocalcitonin from thyroid gland is an example of such feedback control mechanism. It occurs in two ways:

a) When calcium levels are too high, the thyroid detects this and releases calcitonin. calcitonin stimulates the kidneys to release more calcium and it causes bones to absorb more calcium and build more matrix. This is called Negative Feedback Control.

b) In response to a decrease in calcium levels, parathyroid hormone is released, which causes the release of calcium from bone and retention of calcium in the body, and the calcium level rises back to normal. This is called Positive Feedback Control.

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