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Chapter-11 Metabolism of Fatty Acids

BOOK TITLE: Textbook of Biochemistry for Medical Students

Author
1. Vasudevan DM
2. S Sreekumari
3. Vaidyanathan Kannan
ISBN
9789350250167
DOI
10.5005/jp/books/11359_11
Edition
6/e
Publishing Year
2011
Pages
19
Author Affiliations
1. Faculty of Medicine, Amrita Vishwa Vidyapeetham, (Amrita University), Kochi, Kerala, Formerly Principal, College of Medicine, Amrita, Kerala; Formerly, Dean, Sikkim Manipal Institute of Medical Sciences, Gangtok, Sikkim, Amrita Vishwa Vidyapeetham (Deemed University), Cochin, Kerala, E-mail: dmvasudevan@aims.amrita.edu, PG Programs and Research College of Medicine, Amrita Institute of Medical Sciences, Kochi, Kerala, India, College of Medicine, Amrita Institute of Medical Sciences, Kochi, Kerala, India; Sikkim Manipal Institute of Medical Sciences, Gangtok, Sikkim, India
2. Jubilee Mission Medical College, Trissur, Kerala, Sree Gokulam Medical College and Research Foundation, Thiruvananthapuram, Kerala, India, Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India, Government Medical College, Thrissur and Thiruvananthapuram, Kerala, India; Sree Gokulam Medical College and Research Foundation, Thiruvananthapuram, Kerala, India; Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India
3. Amrita Institute of Medical Sciences, Kochi, Kerala, India, Pushpagiri Institute of Medical Sciences and Research Centre, Thiruvalla, Kerala, India, Believers Church Medical College and Hospital, Thiruvalla, Kerala, India
Chapter keywords

Abstract

Digestion of lipids involves the following enzymes, Lingual lipase, gastric lipase and pancreatic lipase. Lipids are absorbed by emulsification and micelle formation with the help of bile salts. Short and medium chain fatty acids are absorbed directly without re-esterification. Defective absorption of lipids occurs in celiac disease, Crohn’s disease. Mammalian tissues oxidize fatty acids primarily by the beta oxidation pathway which occurs in the mitochondria. Transport of fatty acids (long chain acyl CoA) through the inner mitochondrial membrane is facilitated by Carnitine acyl transferase and translocase. Net yield of ATP from one molecule of palmitic acid is 106 ATP. Oxidation of odd chain fatty acids produces propionyl CoA, which may be further metabolized by the TCA cycle. Alpha oxidation and omega oxidation are two other modes of fatty acid oxidation. De novo synthesis of fatty acids occurs in the cytoplasm with the help of a dimeric multi-enzyme complex termed Fatty acid synthase. Synthesis of fatty acid requires NADPH, while degradation requires NAD and FAD. Insulin favors fatty acid synthesis. The white adipose tissue is concerned with energy storage and the brown adipose tissue is concerned with thermogenesis. Obesity is the result of an increase in the fat content of the adipose tissue. It is associated with insulin resistance. Fatty liver refers to deposition of excess triglycerides in the liver cells. It is facilitated by lipotropic factors such as methionine, choline and lecithin. Acetoacetate is the primary ketone body. Beta hydroxy butyric acid and acetone are secondary ketone bodies. Ketosis is seen in diabetes mellitus and starvation. Rothera\'s test is commonly used to detect presence of ketone bodies in urine.

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