True statement about Ca++ absorption from intestines is:-

Calcium ions are actively absorbed into the blood, especially from the duodenum, and the amount of Ca++ ion absorption is exactly controlled to supply the daily need of the body for calcium. One impoant factor controlling Ca++ absorption : Parathyroid hormone Vitamin - D. PTH - (+) vitamin D (PTH activates vitamin D, & the activated vitamin D in turn greatly enhances Ca++ absorption).