Final answer:
To get magnesium and calcium questions right, one should primarily consider parathyroid hormone (PTH), which plays a crucial role in the regulation of these minerals, influencing the release and reabsorption of calcium in the body. Option a.
Step-by-step explanation:
If you want to get magnesium and calcium questions right, think parathyroid hormone (PTH) first. This is because calcium and magnesium's homeostasis is intricately tied to the function of PTH. When blood levels of ionic calcium drop, PTH is secreted by the parathyroid glands.
PTH stimulates the release of calcium ions from bone matrices and increases the reabsorption of calcium by the kidneys. Plus, PTH upregulates the activation of vitamin D in the kidney, which then aids in intestinal absorption of calcium ions, crucial for maintaining proper levels in the blood and for healthy bone structure.
Bones, as storage sites for calcium, release it when blood levels are low, under the regulation of PTH, vitamin D, and calcitonin.
Vitamin D is essential as it promotes calcium absorption in the intestines and is activated in the kidneys into its biologically active form, calcitriol, hence kidneys and vitamin D are also significant in the regulation of these minerals.
However, the initial steps in regulating blood calcium levels do start with the parathyroid hormone, making it the primary focus when considering the regulation of these minerals. Option a.