Lipids: definition, classification, functions. What are lipids? Fig. High Fat/Oil Foods. Lipids, together with carbohydrates, proteins and nucleic acids, are one of the four major classes of biologically essential organic molecules found in all living organisms; their amounts and quality in diet are able to influence cell, tissue and body physiology. Unlike carbohydrates, proteins and nucleic acids they aren’t polymers but small molecules, with a molecular weights that range between 1. The little or absent water- solubility of many of them means that they are subject to special treatments at all stages of their utilization, that is in the course of digestion, absorption, transport, storage and use. Classification of lipids. They may be classified based on their physical properties at room temperature (solid or liquid, respectively fats and oils), on polarity, or on their essentiality for humans, but the preferable classification is based on their structure. Based on structure, they can be classified in three major groups. Simple lipids. They consist of two types of structural moieties. They include: glyceryl esters that is esters of glycerol and fatty acids: e. Metabolic Functions of the Liver. Hepatocytes are metabolic overachievers in the body. They play critical roles in synthesizing molecules that are utilized elsewhere. Lower fat isn't necessarily better. Regularly consuming fewer than 20% of your daily calories from fat (see "Too Low" on the chart above) will put your health at risk. Complex lipids. They consist of more than two types of structural moieties. They include: phospholipids that is glycerol esters of fatty acids; phosphoric acid, and other groups containing nitrogen; phosphatidic acid that is diacylglycerol esterified to phosphoric acid; phosphatidylcholine that is phosphatidic acid linked to choline, also called lecithin; phosphatidylethanolamine; phosphatidylserine; posphatidylinositol; phosphatidyl acylglycerol in which more than one glycerol molecule is esterified to phosphoric acid: e. Derived lipids. They occur as such or are released from the other two major groups because of hydrolysis that is are the building blocks for simple and complex lipids. They include: fatty acids and alcohols; fat soluble vitamins A, D, E and K; hydrocarbons; sterols. ![]() Classification adapted from: Bloor W. R. Proc Soc Exp Biol Med, 1. Christie W. W. 2. ![]() Functions of lipids. They are stored in adipose tissue (triglycerides) and are one of the major energy source. Lipids are the best energy source for humans since at a parity of weight they provide the major part of calories: if carbohydrates, on average, gives 4 kcal/g, as proteins, lipids provide, on average, 9 kcal/g. Moreover, they can be present in foods without there are also fiber or water (for polysaccharides 2 g water/g) allowing to contain a great quantity of energy in a little weight. Mostly of Nutrition Organizations recommend that lipids must contribute up to 3. Some lipids are essential nutrients like fat- soluble vitamins A, (necessary for vision) and D (necessary for calcium metabolism), present in some fats and oils of animal origin, vitamin E (prevention of autoxidation of unsaturated lipids), present in vegetable oils, and vitamin K (normal clotting of blood) present in green leaves, essential fatty acids, in particular linoleic and . This lipoprotein coating is called myelin sheath. Liver: The largest solid organ in the body, situated in the upper part of the abdomen on the right side. The liver has a multitude of important and complex functions. The Recommended Daily Allowances (RDA) for different nutrients were developed on Western diets, and therefore, high-carb diets. Given that a ketogenic metabolism uses. A good quality vitamin and mineral supplement creates a sound micronutrient foundation to accompany a balanced diet. According to the World Health Organization (WHO. Cortisol — Its Role in Stress, Inflammation, and Indications for Diet Therapy By Dina Aronson, MS, RD Today’s Dietitian. The liver is a vital organ of vertebrates and some other animals. In humans, it is located in the upper right quadrant of the abdomen, below the diaphragm. If you are considering a liver cleanse, it may be helpful to have information about the pros and cons, as well as learning about the proper way to do it. Cholecystitis and Choledochitis in Dogs. The gallbladder rests in the abdomen, firmly affixed to the liver and serving as a storage receptacle for bile, a fluid that. On digestive tract they facilitate the digestive process depressing gastric secretion, slowing gastric emptying and stimulating biliary and pancreatic flow. Bile salts (by- products of cholesterol) are natural detergents synthesized in the liver and secreted into bile. They solubilize phospholipids and cholesterol in the bile, permitting the secretion of cholesterol into the intestine (the excretion of both cholesterol and bile salts is the major way by which cholesterol is removed from the body). Bile salts also aid in the digestion and absorption of fat and soluble- fat vitamins in gut. In many animals, some lipids are secreted into external environment and act as pheromones that attract or repel other organisms. They affect the texture and flavor of food and so its palatability. Food manufacturers use fat for its textural properties, e. Chefs know that fat addiction add to the palatability of meal and increase satiety after a meal. References. Akoh C. C. Le basi molecolari della nutrizione. Piccin, 2. 00. 3Bender D. A. Oxford. Bergstroem S., Danielsson H., Klenberg D. The enzymatic conversion of essential fatty acids into prostaglandins. J Biol Chem 1. 96. PC4. 00. 6- PC4. 00. Piccin Editore, 2. Giampietro M. L’alimentazione per l’esercizio fisico e lo sport. Il Pensiero Scientifico Editore. Prima edizione 2. Mahan L. K., Escott- Stump S.: “Krause’s foods, nutrition, and diet therapy” 1. Rosenthal M. D., Glew R. H. Mediacal biochemistry. Human metabolism in health and disease. John Wiley & Sons, Inc. Shils M. E., Olson J. A., Shike M., Ross A. C.: “Modern nutrition in health and disease” 9th ed. Biochemical and physiological aspects of human nutrition. Saunders Company- An imprint of Elsevier Science, 2.
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