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27 Cards in this Set
- Front
- Back
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Oxidation of fuel is endergonic or exergonic?
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Exergonic --> energy yielding
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Why is heart muscle red?
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High content of myoglobin
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What is stage I of catabolism?
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Digestion-GI
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What is stage II of catabolism?
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Anaerobic- Cytoplasm
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What is stage III of catabolism?
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Aerobic- mitochondria
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What are the three primary fuels used by heart muscle?
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1. Lipid
2. Ketone bodies 3. Carbohydrates |
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Fuel choice is based on what 4 principles?
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1. Energy richness
2. Ease of release 3. Availability 4. Demands |
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Carbohydrates can be oxidized?
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Aerobically & anaerobically
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Lipids & ketone bodies can only be oxidized?
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Aerobically
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Energy reserves are stored in the form of?
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Creatine phosphate
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2 ways in which ATP is synthesized?
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1. Substrate-level phosphorylation
2. Oxidative phosphorylation |
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Lipids, ketone bodies & carbohydrates all derive what key molecule for providing heart energy?
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Acetyl-CoA
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What energy source has shortest path to form acetyl-CoA?
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Ketone bodies
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Which enzyme forms acetyl-CoA from ketone bodies?
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Thiolase
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Lipids are broken down by which 2 enzymes to yield glycerol & FFA?
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1. Endothelial lipoprotein lipase
2. Hormone sensitive lipase |
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Free fatty acids (NEFA) undergo ___ in the mitochondria to form ___?
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beta-oxidation to form acetyl-CoA
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What does the heart use for normal energy demands when heart is at rest?
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NEFAs & ketone bodies
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When energy demands for the heart increase what type of fuel is used?
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Carbohydrates
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What is end product of anaerobic glycolysis by muscles?
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Lactate
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What happens to lactate produced by skeletal muscles during exercise
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Myocardium uses it as fuel-- LD-H isoenzyme
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Why can heart use lactate as fuel source?
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Heart LD has low Km for lactate & is able to convert it to pyruvate --> acetyl CoA
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What does the cori cycle do?
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Lactate produced in muscles --> gluconeogenesis in liver --> Produces glucose which is transported in blood
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Why is lactate used by heart during heavy exercise instead of glucose?
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Glucose is spared for nutrition of brain & hypoxic tissues
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When can fatty acids & ketone bodies not be used as fuel for heart?
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Under hypoxic conditions
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ATP production falls during hypoxia in the heart because? (2)
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1. Limited fuels available-- carbs only
2. Inability to oxidize fuels aerobically |
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When ATP reserves are exhausted, what does myocardium adapt to for survival?
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Adenosine from AMP --> powerful vasodilator to restore blood flow
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During ischemia what happens?
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1. Fuel & O2 are limitied
2. Shifts to anaerobic glycolysis but lacks glucose 3. Myocardium dies |
