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I_BBMetabolism - ENERGY METABOLISM Getting Fuel from Food...

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Unformatted text preview: ENERGY METABOLISM Getting Fuel from Food Metabolism Defined All chemical reactions within organisms that enable them to maintain life Includes Catabolic reactions ENERGY METABOLISM Transferring food energy to cellular energy Stage 1: Stage 2: Breakdown into molecules that can enter metabolic pathways (catabolic) Stage 3: Largescale ATP production We talked about these before Stage 1: Digestion & Absorption Carbohydrates yield glucose: used by brain, RBC's, CNS & all other cells stored as glycogen in liver & muscles OR eventually as fat Digestion & Absorption, con't Fats yield glycerol + fatty acids: used as energy by cells stored as fat Proteins yield amino acids: used to build body protein will provide energy if NECESSARY! stored as fat if in excess Stage 2: Molecules to enter metabolic pathways Glucose Pyruvate Fatty Acids Acetyl CoA Amino Acids Acetyl CoA or ? (Varies) Let's take a look... Getting Fuel from CARBOHYDRATE GLUCOSE (a 6carbon molecule) 2 PYRUVATE (2, 3C molecules) Coenzyme A O AVAILABLE 2 2 ACETYLCoA + 2 CO2 (acetyl is a 2carbon molecule) TCA/Krebs/Citric Acid Cycle And electron transport chain ATP + H2O + CO2 (Stage 3) Getting Fuel from FAT FATTY ACID ACETYLCoA + 2 CO2 (acetyl is a 2carbon molecule) TCA/Krebs/Citric Acid Cycle And electron transport chain ATP + H2O + CO2 (Stage 3) Getting Fuel from PROTEIN 3 Many amino acids 3 PYRUVATE Some amino acids 3 ACETYLCoA Some amino acids NH removed TCA/Krebs/Citric Acid Cycle And electron transport chain ATP + H2O + CO2 (Stage 3) A LOOK AT ALL THE MACRONUTRIENTS GLUCOSE GLYCOLYSIS AMINO ACIDS PYRUVATE AMINO ACIDS AMINO ACIDS ACETYLCoA BETAOXIDATION FATTY ACIDS TCA/Krebs/Citric Acid Cycle And electron transport chain ATP + H2O + CO2 ANOTHER KEY CONCEPT The citric acid cycle requires a steady flow of carbohydrate to keep it running without carbohydrate accumulation of acetylCoA Ketone Bodies can be used by the brain for energy in absence of glucose KETOSIS When might this occur? What is the consequence AN OVERVIEW OF METABOLISM DURING FEASTING DURING DURING FASTING DURING DURING PROLONGED FASTING DURING (STARVATION) WHEN WE "FEAST" WHEN WE "FAST" DURING PROLONGED FASTING CHANGING GEARS Alcohol Metabolism Alcohol metabolism The nutritional impact Alcohol requires no breakdown On an empty stomach ~20% of alcohol is absorbed in the stomach Alcohol metabolism The nutritional impact Metabolic pathway for alcohol Some alcohol dehydrogenase in stomach Alcohol metabolism The nutritional impact Liver tries to "detoxify" the blood before it is sent out to other parts of the body Metabolism of alcohol in the liver disrupts TCA Cycle Amino Acid Metabolism ESSENTIALLY ALL NORMAL FUNCTIONS OF THE LIVER Alcohol metabolism continued With moderate drinking... our metabolism can "keep up" "Social Drinker" ~150 lbs: can metabolize ~812 oz beer per hour highly individual Above this, liver's metabolic capacity is exceeded and intoxication occurs Weighing the risks/benefits of alcohol Alcohol is associated with at least 100,000 deaths from diseases and injuries in US each year Moderate alcohol may prevent 80,000 deaths from CHD each year Even modest alcohol use is not advised for some What constitutes moderation? 10 oz wine cooler 12oz beer 1 1/2 oz hard liquor (80 proof whiskey, gin, brandy, rum, vodka) 5 oz wine Adverse effects of excess alcohol Short term: Binge drinking: confusion, unconsciousness, coma, death Dehydration, hangovers Longer term: Increased liver disease (eventual cirrhosis) Increased cancer risk (esophagus, breast, pancreas, mouth) Stomach problems (pain, bleeding) Brain cell loss; dementia Depression, anxiety, insomnia Malnutrition Kidney failure High blood pressure UP NEXT... Vitamins and Minerals ...
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