口腔生物化学0601（Oral Biochemistry 0601）.doc

口腔生物化学0601（Oral Biochemistry 0601） I. an overview of lipids (I) classification Lipids are organic compounds that are insoluble in water and are soluble in organic solvents and can be used by the body. Including fat and lipids, fat is also called triglyceride. Lipids include cholesterol, phospholipids, glycolipids, and so on. (two) physiological function 1. energy storage and energy supply. About 17% to 25% of the energy required for normal physiological activity is supplied by fat, and more than 50% of the bodys energy comes from oxidation of fat. After a complete oxidation of fat per gram, the average release of 9.3kcal (38.94kJ) energy is about twice as much as the same amount of sugar or protein, so fat is the main source of energy in fasting and starvation. In addition, fat also has the function of keeping body temperature, protecting the internal organs and helping the absorption of fat soluble vitamins. 2. the composition of the biofilm. Lipids, especially phospholipids and cholesterol, are important components of biological membranes. Phospholipids constitute the basic structure of biological membranes in the form of bilayers, in which sphingomyelin is a major component of the myelin sheath. Cholesterol plays an important role in maintaining the permeability of biological membranes. In addition, glycolipid and lipoprotein are also involved in the formation of biological membranes. Signal transduction in cell membranes acts as a carrier and receptor. 3. participate in the transmission of intercellular information and regulate the metabolism of organism. Such as essential fatty acids in vivo can be evolved to produce prostaglandins, thromboxane and leukotrienes, etc. these derivatives are involved in the regulation of multiple cell metabolism. Vitamin D 3 produced by conversion of cholesterol to the activity of regulating calcium and phosphorus metabolism. Cholesterol can also be converted into alcohol, hormone involved in metabolism. In addition, phosphatidyli