In the fasting state, glucose is obtained from

Functions of Glycogen - 1)Glycogen is the storage form of carbohydrates in the human body. The major sites of storage are liver and muscle. The major function of liver glycogen is to provide glucose during fasting. The glycogen content of liver (10 gm/100 gm tissue) is more than in the skeletal muscle (1-2 gm/100 gm). But the total quantity of muscle glycogen is more than liver glycogen because of the larger muscle mass. 2. When blood glucose level falls, liver glycogen is broken down and helps to maintain blood glucose level. After taking food, blood glucose tends to rise, which causes glycogen deposition in liver. About 5 hours after taking food, the blood glucose tends to fall. But, glycogen is lysed to glucose so that the energy needs are met. After about 18 hours fasting, most of the liver glycogen is depleted, when depot fats are hydrolysed and energy requirement is met by fatty acid oxidation. 3. The function of muscle glycogen is to act as reserve fuel for muscle contraction. 4. All the enzymes related to glycogen metabolism are cytoplasmic. Ref: DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY, EIGHTH EDITION, PG.NO.,140.