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 Bones-Parathyroid hormone stimulates the release of calcium from large calcium stores in the bones into the bloodstream. 2  This increases bone destruction and decreases the formation of new bone.3  Kidneys-Parathyroid hormone reduces loss of calcium in urine.arathyroid hormone is secreted by the parathyroid glands and is the most important regulator of calcium levels in the blood and within the bones. Alternative names for parathyroid hormone PTH; parathormone; parathyrin.