One of the characteristic features of a living cell is that it controls the exchange of electrically charged ions across the cell membrane and therefore the electrical potential of its interior relative to the exterior. This Scholarpedia page is a basic introduction into the mechanisms underlying this process.
Here are the ranges for total cholesterol in adults: 1  Normal: Less than 200 mg/dL. 2  Borderline high: 200 to 239 mg/dL. 3  High: At or above 240 mg/dL.
The American Heart Association defines normal total cholesterol as less than 200 mg/dL. Total serum cholesterol above 200 is borderline high and raises your risk of heart disease. Total serum cholesterol above 240 is considered high.