Understanding Carbohydrate Metabolism: Energy Source and Digestion Process

1. CARBOHYDRATE CARBOHYDRATE METABOLISM

2. *CHO is called quick energy . *CHO major source of energy. @Importance of CHO diet : 1-easily grown in plants ( grains ,vegetables ,fruits ). 2-low coast . 3-stored easily .

3. monosacharrides • Disacharrides • Poly sacharrides

4. ** classification of CHO : CARBON ,HYDREGEN ,OXYGEN @ monosaccharide: simple ( single sugar ) glucose ,fructose ,galactose . glucose : -sweet sugar -found in corn syrup - comes from starch digestion . - old name dextrose . - running in the blood stream . - normal glucose level 70-110 mg %. b-fructose : -the sweetest of simple sugar . - founds in honey , fruits . - during metabolism ,fructose converted to glucose ,to form energy .

5. c-galactose : • - produced by human digestion . • -lactose change to glucose to form energy . • @ Disaccharides: • -two sugar molecules linked together . • - sucrose ,lactose ,maltose . • * sucrose ( glucose + fructose ). • * lactose (glucose + galactose ). • * maltose (glucose+ glucose ).

6. a-sucrose : • - table sugar . • -made from sugar cane ,& sugar beets . • -30-40 % contribute in the total Kcal . • -found in pineapple & carrots . • b-lactose : • -sugar in milk is called lactose . • -the least sweet disaccharides . • c-maltose: • -malt product of starch breakdown ,& germinating cereal grains

7. @ polysaccharides: • made-up of many sugar unit . • - most important one is starch . • Other type glycogen & dextrin & non digest able form of dietary fiber ( cellulose & noncellulose ),that provide important bulk in the diet .

8. *starch: • - most significant poly-saccharides . • -made up of many chains of simple glucose . • - starch mixture is thickened by cooling , because the starch granules has gel like quality that thick the mixture . • - important source of dietary CHO . • - significant factor in human nutrition . • -major food that contain starch include ( cereal grains ,legumes ,potatoes ,& other vegetables ).

9. * glycogen: - it forms during cell metabolism . - stored in small amount in the liver & muscle tissue , help to sustain normal blood glucose level during fasting period such as sleeping hours . -dietary CHO is essential to maintain these needed . - glycogen storage prevent the symptoms of low CHO intake ( fatigue ,dehydration ,& energy loss ).

10. -* dextrin: • -formed from break down of starch . • - starch+ water = soluble starch + maltose . • - soluble starch + maltose =dextrin + maltose . • -dextrin + water =maltose . • -maltose + water = glucose + glucose .

11. *oligosaccharides :- • - small portion of partially digested starch . • - it is irregular form . • - used in special formula for infant , or person with gastro-intestinal problem ,because it is easier to digest .

12. -* dietary fiber : - cellulose found in the framework of plants , the human cant digest it , because lack of digestive enzyme , so it form bulk of diet thus stimulate peristalsis .

13. ** Function of CHO: • 1-energy production . • 2-glycogen storage in the liver & muscle . • 3-regulation protein metabolism . • 4-anti-ketogenic effect { prevent formation of keton bodies from fat . • keton bodies accumulated in case of {starvation ,un controlled DM, very low CHO diet }. • -5- heat action [ contractile process of the heart ]. • -6-CNS stimulation { hypoglycemic shock lead to irreversible brain damage }.

14. * Digestion of CHO: • @ mechanical or muscular function that break the food into small particles . • @ chemical process in which specific enzyme break down food in to smaller usable metabolic product .

15. mouth : mastication breaks food into fine particles & mix it with salivary secretion . • -salivary amylase is secreted by parotid gland act on starch to break it in to starch & maltose . • Stomach ,mix food with gastric secretion, no specific enzyme break down of CHO . • - more food by peristalsis go to the 1st portion of the small intestine through pyloric sphincter . • Small intestine : • Mechanical & chemical digestion of CHO is completed in small intestine by intestinal & pancreatic enzyme

16. Pancreatic enzyme: Secretion of pancreas enter the duodenum . Pancreatic amylase break down of starch & maltose . Intestinal secretion : Sucrase , lactase , maltase act on disaccharides to change it in to glucose ,galactose ,& fructose to be ready for absorption

17. ** absorption of CHO: -glucose carried in to the cell to produce energy or storage . -the major glucose absorption mechanism is an active transport [ pumping system ] requiring Na as carrier substance . - villi & micro-villi absorb about 90% of digested food . -simple sugar enter portal circulation to liver

18. ** metabolism of CHO : • - chemical process in living • Organics by which energy is made available for function of entire organism • - cells are the functional unit of life in human body . • - the most important end product of CHO digestion is glucose . • - the liver is the major site of handling glucose . • -in the cell glucose is burned to produce energy through chemical reaction . • -extra glucose not immediately needed for energy may changed to fat & stored

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