Now, the bone is also responsible for storing important types of minerals that are used by the body, by the cells. And one example of the mineral stored is calcium. So when the blood levels, if we find too much calcium in the blood, the bone is responsible for taking that calcium out of the blood and depositing the calcium into the bone. But if the blood level of calcium is low, then if the calcium level in the blood is low, that basically means the bone can actually release calcium into the blood and then the calcium can go to the cell that requires that calcium. So remember, calcium is important. For example, in muscle contraction.