Calcium homeostasis
Calcium homeostasis refers to the regulation of calcium levels in the body, which is essential for numerous physiological processes including muscle contraction, nerve transmission, blood clotting, and bone formation. The body tightly controls calcium levels through a complex interplay between the parathyroid hormone (PTH), calcitonin, and vitamin D.
When blood calcium levels are low, the parathyroid glands release PTH, which acts on the bones to release calcium, the kidneys to reabsorb calcium, and the intestines to absorb more calcium from food. PTH also stimulates the production of active vitamin D, which helps to increase calcium absorption from the intestines.
On the other hand, when blood calcium levels are high, the thyroid gland releases calcitonin, which inhibits the breakdown of bone and promotes the excretion of calcium by the kidneys.
Overall, calcium homeostasis is critical for maintaining the proper functioning of the body and preventing diseases such as osteoporosis, hypercalcemia, and hypocalcemia. Proper nutrition, adequate sunlight exposure for vitamin D synthesis, and regular exercise are important factors in maintaining calcium balance.