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.
Parathyroid glands. The parathyroid glands are located on the posterior of the thyroid gland. The parathyroid glands produce parathyroid hormone (PTH) which increases blood calcium concentrations when calcium ion levels fall below normal. One of the parathyroid glands' most important functions is to regulate the body's calcium and phosphorus levels.