Final answer:
When calcitonin is released, it does not have a direct effect on the intestinal absorption of calcium. Its primary role is to decrease blood calcium levels by inhibiting osteoclast activity and increasing calcium excretion in the kidneys, rather than affecting the intestines.
Step-by-step explanation:
In calcium homeostasis, when calcitonin is produced by the thyroid gland, it decreases blood calcium levels by inhibiting the activity of osteoclasts, which are the bone cells responsible for resorbing bone tissue and releasing calcium into the blood. This hormone also works to reduce the affinity of the kidneys for the reabsorption of calcium, effectively promoting the excretion of calcium. However, the effects of calcitonin on the intestines are less direct compared to those of PTH (parathyroid hormone). While PTH increases calcium absorption in the intestines by stimulating the formation of calcitriol, a form of vitamin D, calcitonin does not have a direct effect on the intestinal absorption of calcium.
Thus, when calcitonin is released, there is no significant impact on the absorption of calcium in the intestines. Instead, its primary role is to decrease calcium concentrations in the blood by other means, such as inhibiting osteoclasts and increasing renal excretion. Therefore, in terms of intestinal activity, calcitonin's secretion does not lead to increased calcium absorption from the digestive tract.