Which three hormones are secreted by the parathyroid glands?

The correct response highlights the hormones that are secreted by the parathyroid glands, which primarily include parathyroid hormone (PTH). PTH plays a crucial role in regulating calcium levels in the blood, working to increase calcium concentration when it is low by stimulating the release of calcium from bones, enhancing calcium reabsorption in the kidneys, and promoting the activation of vitamin D to increase dietary calcium absorption in the intestines.

Calcitonin, which is actually secreted by the thyroid gland, helps to decrease blood calcium levels, acting in opposition to PTH. Thyroxine, on the other hand, is also produced by the thyroid gland and is involved in regulating metabolic processes in the body.

Thus, while PTH is correctly identified as a key hormone produced by the parathyroid glands, calcitonin and thyroxine do not originate from the parathyroid glands, making this choice inaccurate. The specific hormonal action of PTH clearly delineates its role in calcium homeostasis, emphasizing the significance of the parathyroid glands in maintaining mineral balance in the body.