Chapter 6 introduced an essential part of the cell: the. plasma membrane. Thanks to the selective permeability of. phospholipid bilayers and the activity of membrane trans-. port proteins, this structure creates an internal environment. that is different from conditions outside the cell. Our task.
When calcium levels decrease, this stimulates the parathyroid gland to release parathyroid hormone. Parathyroid hormone encourages the normal process of bone breakdown (essential for maintenance and growth of the bone). This process of bone breakdown releases calcium into the bloodstream.
When needed, parathyroid hormone is released by the parathyroid glands into the blood and causes the bones to release calcium and increase levels in the bloodstream.hen needed, parathyroid hormone is released by the parathyroid glands into the blood and causes the bones to release calcium and increase levels in the bloodstream.