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Chapter-07 Metabolism of Carbohydrates

BOOK TITLE: Essentials of Biochemistry for Medical Students

Author
1. B Shivananda Nayak
ISBN
9788184487718
DOI
10.5005/jp/books/11024_7
Edition
1/e
Publishing Year
2010
Pages
46
Author Affiliations
1. University of the West Indies, Trinidad and Tobago, West Indies; Subbaiah Institute of Medical Sciences, Shivamogga, Karnataka, India
Chapter keywords

Abstract

Carbohydrates are the essential component of diet. The pancreatic and intestinal enzymes hydrolyse the polysaccharides to simple monosaccharides. The galactose and glucose are absorbed very rapidly by the active process. Fructose and mannose are absorbed by a Na+ independent facilitative diffusion. Glucose is the main source of energy to our body. Glucose undergoes glycolysis to generate the energy in the form of ATP. Pyruvate formed in glycolysis converted to acetyl CoA which enters TCA cycle to generate large number of ATPs. The acetyl CoA is also required to synthesize cholesterol, fatty acids, ketone bodies and steroid hormones. Insulin stimulates the glycogenesis through which excess glucose absorbed will be converted to glycogen and stored in muscle and liver. Hyperglycemic hormones stimulate the glycogen breakdown when glucose level goes down. Glycogenesis and glycogenolysis are regulated by glycogen synthase and glycogen phosphorylase respectively. Hyperglycemic also hormones stimulate the gluconeogenesis. Hexose monophosphate pathway generates large number of NADPH which is required to maintain the active reduced glutathione peroxidase and to synthesize fatty acids. Pathway also produces ribose sugars which is the essential component for the synthesis of nucleic acids. The insulin deficiency results in diabetes mellitus which are of tow types: insulin dependent diabetes mellitus and non insulin dependent diabetes mellitus. The major complications of diabetes are retinopathy, nephropathy and neuropathy. The fasting blood glucose and HbA1c are used to detect and monitor diabetes. Oral glucose tolerance test is preferred to detect the diabetes mellitus during pregnancy and other conditions.

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