To answer this question we need to remember quickly how smooth ER works. Smooth ER is a complex of membranes through which processed lipids and calcium is stored, also is involved in process of depuration of certain toxins as well as glycogenolysis an essential process to maintain glucose levels in the blood. So considering this, we can compare it to a zone of fast food, this food is rich in fat and also is involved in providing energy to customers, as well part of this food is packaged and can be moved to other parts of the mall, even more, each food pendant has is own store that can be compared to calcium reserves.