MICROANATOMY

Detailed explanation-1: -These glands precisely control the level of calcium in the blood.

Detailed explanation-2: -Bone cells called osteoblasts build bone, while other bone cells called osteoclasts break down bone if calcium is needed.

Detailed explanation-3: -When the blood calcium ion level drops below its homeostatic level, the parathyroid glands (located in the throat) are stimulated to release parathyroid hormone (PTH) into the blood. PTH activates osteoclasts, giant bone-destroying cells in bones, to break down bone matrix and release calcium ions into the blood.

Detailed explanation-4: -Almost 99% of the body’s calcium is found in the bones. A small amount of calcium is absorbed into the blood and used for the healthy functioning of the heart, muscles, blood and nerves. Bones act like a calcium bank.

Detailed explanation-5: -The bones act as a storage site for calcium: The body deposits calcium in the bones when blood levels get too high, and it releases calcium when blood levels drop too low. This process is regulated by PTH, vitamin D, and calcitonin. Cells of the parathyroid gland have plasma membrane receptors for calcium.