Question

calcium regulation is controlled by hormones. complete each sentence to explain how the body maintains normal blood calcium levels.
osteoblasts
parathyroid hormone (pth)
calcitonin
calcium
phosphorus
vitamin d
osteoclasts
if blood calcium levels drop, the parathyroid glands secrete

this hormone signals bone cells called to
tear down bone tissue.

as a result, is released from bone cells and
enters the bloodstream

if calcium levels in the blood become too high, the thyroid
gland secretes

this hormone signals another type of bone cell, the
to remove excess calcium from the blood
and build bone tissue.

Explanation:

• When blood calcium levels drop, parathyroid glands secrete parathyroid hormone (PTH). PTH signals osteoclasts (bone - breaking cells) to tear down bone tissue. As a result, calcium (stored in bone) is released into the bloodstream.
• When blood calcium levels are too high, the thyroid gland secretes calcitonin. Calcitonin signals osteoblasts (bone - building cells) to remove excess calcium from the blood and build bone tissue.

Answer:

1. parathyroid hormone (PTH)
2. osteoclasts
3. calcium
4. calcitonin
5. osteoblasts