Final answer:
Calcitonin regulates calcium concentration by inhibiting osteoclasts, stimulating osteoblasts, and stimulating calcium excretion by the kidneys. It also decreases calcium absorption in the intestines.
Step-by-step explanation:
Calcitonin is a hormone produced by the thyroid gland that helps regulate blood calcium levels. It decreases blood calcium levels by inhibiting osteoclasts, stimulating osteoblasts, and stimulating calcium excretion by the kidneys. Calcitonin also decreases calcium absorption in the intestines.
When blood calcium levels are high, cells in the thyroid gland sense the increase and release calcitonin. Calcitonin inhibits the activity of osteoclasts, which are responsible for breaking down bone and releasing calcium into the blood. It also stimulates osteoblasts, which are responsible for bone formation, leading to the uptake of calcium from the blood and deposition in the bones. Additionally, calcitonin enhances calcium excretion by the kidneys, further reducing blood calcium levels.
Calcitonin plays an important role in children, promoting bone growth. It also decreases maternal bone loss during pregnancy and reduces bone mass loss during prolonged starvation. However, its role in healthy nonpregnant, unstarved adults is unclear.