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.
NCEP defines a desirable total cholesterol level as less than 200 mg/dL, and levels for most women stay in the healthy or desirable range until middle-age. But between the ages of 45 and 55, women's average total cholesterol rises to almost 220 mg/dL. Between the ages of 55 and 64, those levels average 240 mg/dL. Total cholesterol levels between 200 and 239 mg/dL are considered borderline high, meaning you have a borderline-high risk of developing heart disease. Levels of 240 mg/dL and above put you in the high-risk category for developing heart disease. LDL cholesterol levels less than 100 mg/dL are considered optimal, according to NCEP guidelines.