Calcium homeostasis is primarily maintained through negative feedback mechanisms. This means that the body uses a process that counteracts any changes that deviate from the optimal calcium level in the bloodstream.
Here’s how it works: When calcium levels in the blood drop, the parathyroid glands release parathyroid hormone (PTH), which acts to raise the calcium levels by stimulating the release of calcium from bones, increasing calcium reabsorption in the kidneys, and enhancing the intestinal absorption of calcium. Conversely, if calcium levels become too high, the thyroid gland releases calcitonin, which lowers calcium levels by promoting the deposition of calcium in bones and inhibiting calcium reabsorption in the kidneys. This regulatory loop ensures that calcium levels stay within a healthy range, demonstrating a clear negative feedback system.