Question

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

Short answer

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.

Step-by-step solution

Introduction to Thyroid and Parathyroid Glands

The thyroid and parathyroid glands are essential parts of the endocrine system that play vital roles in maintaining blood calcium homeostasis. Blood calcium levels must be kept in a specific range, as calcium is essential for many bodily functions, like muscle contraction and nerve function. The thyroid and parathyroid glands maintain this balance by releasing hormones that regulate calcium levels.

Thyroid Gland's Role in Calcium Homeostasis

The thyroid gland produces a hormone called calcitonin, which is released when blood calcium levels are too high. Calcitonin helps lower calcium levels in the blood by inhibiting the release of calcium from bones and increasing the amount of calcium excreted in urine. This reduces the amount of calcium in the bloodstream, bringing blood calcium levels back within a normal range.

Parathyroid Glands' Role in Calcium Homeostasis

The parathyroid glands, located behind the thyroid gland, produce a hormone called parathyroid hormone (PTH). PTH is released when blood calcium levels are too low. It works to increase calcium levels by stimulating the release of calcium from bones, increasing the reabsorption of calcium in the kidneys, and increasing the activation of vitamin D, which helps the body absorb calcium from food. As a result, blood calcium levels rise back into the normal range.

Working Together for Calcium Homeostasis

In summary, the thyroid and parathyroid glands work together to maintain blood calcium levels within a normal range. When blood calcium levels are too high, the thyroid gland releases calcitonin to bring calcium levels down. When blood calcium levels are too low, the parathyroid glands release PTH to increase calcium levels. Through the actions of these hormones, the thyroid and parathyroid glands ensure that blood calcium levels remain balanced, which is essential for the proper functioning of the body.