Which hormone helps to regulate calcium levels in the blood?

The hormone that helps to regulate calcium levels in the blood is parathyroid hormone. This hormone is produced by the parathyroid glands and plays a crucial role in maintaining calcium homeostasis. When calcium levels in the blood drop, parathyroid hormone is released, leading to several physiological responses.

Firstly, it promotes the release of calcium from bones into the bloodstream by stimulating osteoclast activity, which breaks down bone tissue. Secondly, it increases renal tubular reabsorption of calcium, which means that the kidneys will retain more calcium rather than excreting it in urine. Lastly, parathyroid hormone enhances the conversion of vitamin D to its active form, which in turn increases intestinal absorption of calcium from dietary sources.

This complex regulatory mechanism ensures that the body maintains appropriate levels of calcium, which is vital for numerous bodily functions, including nerve conduction, muscle contraction, and blood clotting.