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Contents | Index |
11 Cholesterol metabolism
Subsections:
11.1 Uptake and transport of cholesterol
11.2 Synthesis of cholesterol
11.3 Regulation of cholesterol synthesis
11.4 Cholesterol in atherosclerosis
11.1 Uptake and transport of cholesterol
11.2 Synthesis of cholesterol
11.3 Regulation of cholesterol synthesis
11.4 Cholesterol in atherosclerosis
Contrary to popular belief, the biological role of cholesterol is not limited to being the bad guy. Instead, it has a number of essential physiological functions:
- In each individual cell, it occurs as a major constituent of the plasma membrane. Cholesterol controls physical properties of the membrane, which are important for the function of membrane proteins such as receptors and transporters. Depletion of membrane cholesterol cripples many functions of cells.
- Cholesterol is the precursor of bile acids, which are essential for fat digestion.
- Cholesterol is the precursor of all steroid hormones: Androgens, estrogens, gestagens, glucocorticosteroids, mineralocorticoids, and calciferols. Some examples are illustrated in Figure 11-1.
Cholesterol can both be obtained from the diet and be synthesized in human metabolism. However, we cannot degrade it; therefore, cholesterol has no significant role in energy metabolism. I'm going to cover it here anyway because its relationship to fat metabolism and its medical and physiological relevance.