So we break down more bone matrix and we release more calcium into our blood, thereby increasing the concentration of calcium in our blood. Now, the parathyroid hormone also actually affects our kidneys, so it increases the amount of calcium that is reabsorbed by our kidneys, and this increases the concentration of calcium in our blood and decreases the amount of calcium found in our urine. Now, it also affects our intestines. So what our parathyroid hormone does is it activates vitamin D, produces the active form of vitamin D in the kidneys, and then this vitamin D basically helps to absorb more calcium in our intestines. So notice these three things that we just mentioned are the opposite of what our calcitonin does released by the thyroid gland. So notice that the parathyroid hormone reverses the effects of calcitonin.