When blood levels of calcium decrease, the parathyroid gland releases PTH which causes an increase in calcium. This increase in calcium, in turn, stimulates the release of ____

When blood levels of calcium decrease, the parathyroid gland releases PTH which causes an increase in calcium. This increase in calcium, in turn, stimulates the release of calcitonin

Explanation:

Parathyroid gland releases parathyroid hormone (PTH) which increases the Ca levels of blood While thyroid gland releases calcitonin which decreases the calcium levels in the blood.

Ca is regulated in the blood by feedback mechanism:

When blood levels of calcium increases, parathyroid gland releases PTH which acts on the bones, casuing the osteoclasts to degrade the bone matrix and release Ca ions in the blood resulting in an increase in blood levels of calcium.

As the calcium is increased in the blood, thyroid gland detects it and releases calcitonin which causes a decrease in blood calcium levels.