Explain how the thyroid and parathyroid glands work together to maintain blood calcium homeostasis. (pages \(336-37\) )

The thyroid and parathyroid glands work together to maintain blood calcium homeostasis. The thyroid gland produces calcitonin, which helps lower high blood calcium levels by inhibiting the release of calcium from bones and increasing calcium excretion in urine. On the other hand, when blood calcium levels are too low, the parathyroid glands release parathyroid hormone (PTH), which increases calcium levels by stimulating the release of calcium from bones, increasing calcium reabsorption in the kidneys, and activating vitamin D to improve calcium absorption from food. Through these actions, the thyroid and parathyroid glands collaborate to keep blood calcium levels within a normal range, ensuring proper bodily functions.