Final answer:
A serum calcium level of 11.5 mg/dL would typically trigger the release of b) calcitonin from the thyroid gland to reduce blood calcium levels by inhibiting osteoclasts and decreasing renal calcium reabsorption.
Step-by-step explanation:
Under normal physiological conditions, a serum calcium level of 11.5 mg/dL would typically trigger an adaptive response involving the release of calcitonin from the thyroid gland. Calcitonin works by reducing blood calcium levels, primarily by inhibiting the activity of osteoclasts, which are the cells responsible for breaking down bone and releasing calcium into the blood. This hormone also reduces calcium reabsorption in the kidneys, contributing to lower blood calcium levels. In contrast, parathyroid hormone (PTH) is released when blood calcium levels are low, and its role is to increase calcium levels by stimulating osteoclasts, enhancing calcium absorption in the intestines through the action of calcitriol, and increasing calcium reabsorption in the kidneys.