Blood calcium must be tightly regulated to prevent health pr…

Blood calcium must be tightly regulated to prevent health problems. In the case of low blood calcium, chemoreceptive cells within the parathyroid glands detect the drop in Ca2+. This signals the synthesis of the hormone parathyroid hormone (PTH). PTH enters the blood, inhibits the loss of calcium in the urine, and encourages osteoclasts and osteocytes to resorb bone and release calcium into the blood, leading to a return to homeostasis. Is this an example of negative or positive feedback? In this example, what structure is the receptor? What structure is the integrating (control) center? What structure(s) serve as effectors? List at least one example.