Answer:
The parathyroid glands secrete a hormone that causes the release of calcium from bone into the blood.
Step-by-step explanation:
Parathyroid glands have a role to control calcium level in the bloodstream. It is also important, in order to ensure the nervous system, so the body's muscles can work properly and that bones remain strong.
When calcium levels are low, this hormone is released by the parathyroid glands, into the blood, and it causes bones to release calcium and increase the levels in the bloodstream.
If a person doesn't take calcium through their meals, or if they don't have enough vitamin D in their system, calcium level D can be produced by parathyroid hormone.