Overview of Carbohydrate Metabolism
Carbohydrate metabolism begins with digestion in the small intestine where monosaccharides are absorbed into the blood stream. The pathways used in carbohydrate metabolism are shown in the following diagram:
(Source: http://www.unisanet.unisa.edu.au/08366/timages/chosum2.gif)
Blood sugar concentrations are controlled by three hormones: insulin, , and epinephrine., insulin is secreted by the pancreas.
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HORMONE
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Source
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Target tissue
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Action
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Insulin
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Pancreas
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Liver and Muscle
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stimulates the transfer of glucose into the cells, if concentration of glucose in the blood is too high.
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Epinephrine
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Pancreas
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Muscle
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Stimulate the conversion of glycogen to glucose( glycogenolysis).
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Glucagon
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Pancreas
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Muscle
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Stimulate the conversion of glycogen to glucose( glycogenolysis).
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Glycolysis just releases little ATP. For more energy, the reaction should continue into citric acid cycle and respiration. In this cycle, pyruvic acid convert to acetyl CoA then citric acid. The majority of the ATP is made from oxidations in the citric acid cycle in connection with the electron transport chain. |
