The smooth endoplasmic reticulum is responsible for some carbohydrate metabolism. In the liver, for example, the cell breaks down the polysacharide glycogen. Eventually, the glycogen will be turned into glucose, and released into the blood, but first it is broken into glucose phosphate, an ion that, if released would harm our blood cells. So to remedy this, an enzyme found in the membrane of the smooth endoplasmic reticulum can remove the phosphate, allowing pure glucose to be released.