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.
1 Parathyroid hormone regulates the bodyâs calcium levels. 2  There are four parathyroid glands, and they are each about the size of a grain of rice. 3  Though theyâre located near each other, the parathyroid glands are not related to the thyroid gland.he thyroid gland regulates the bodyâs metabolism, while parathyroid glands regulate calcium levels and have no effect on metabolism. Parathyroid Hormone. Parathyroid hormone (PTH) has a very powerful influence on the cells of your bones by causing them to release their calcium into the bloodstream.