Hormone is controlled by a (positive/negative) feedback system between the glands that produce this hormone and the
concentration of blood calcium ions. If the level of ions is
(high/low), hormone secretion is increased. This causes
resorption by
cells called
which releases both calcium and phosphate ions into the blood stream.

Hormones are controlled by a

(negative)

feedback system between the glands that produce this hormone and the  concentration of blood calcium ions. If the level of ions is

(low)

,hormone secretion is increased. This causes  resorption by  cells called

which releases both calcium and phosphate ions into the blood stream.

Explanation:

Negative Feedback a the process in your body that helps to maintain Homeostasis. If some variable changes a value in your body, like your ion levels,  your glands produce a hormone that causes resorption by  cells. This releases both calcium and phosphate ions into the blood stream and therefore your ion levels go back to normal.

Hope this helps!