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Nutrition363
| Question | Answer |
|---|---|
| Bioenergetics | The ability to convert food stuffs into a biologically useful form of energy. |
| Components of Total Energy Expenditure (TEE) | Resting metabolism, Thermic effect of blood, physical activity |
| Basal metabolic rate (BMR) | *Minimal amount of energy needed to sustain life *Measured under defined laboratory conditions *Used for research |
| Resting metabolic rate (RMR) | *Estimate of BMR *Measured under less strict conditions *RMR is typically 10% greater than BMR |
| Carb & Protein kcal/g? | 4kcal/g |
| Fat kcal/g? | 9kcal/g |
| Alcohol kcal/g? | 7kcal/g? |
| Direct calorimeter | A. Measures temperature change by measuring heat associated with energy expenditure B. Whole-room calorimeters are used for research |
| Indirect calorimeter | A. Measures relationship between oxygen consumption, carbon dioxide production, and energy expenditure B. Whole-room calorimeters are used for research |
| Thermic Effect of Food (TEF) | a. Energy required for the digestion and absorption of food b. Estimated to be 10% of total caloric intake for the day c. Proteins increase TEF more than carbohydrates d. Effect of TEF on RMR is very small |
| Rephosphorylation of ADP to form ATP | 1. Hydrolysis of ATP 2. Rephosphorylation of ADP to form ATP 3. Use of ATP for energy by exercising skeletal muscle |
| Creatine phosphate and ATP | Very fast, very short duration, very small amount |
| Anaerobic glycolysis and ATP | Fast, short duration, small amount |
| Oxidative phosphorylation and ATP | Very slow, very long duration, large amount |
| What is creatine? | 1. Amine (nitrogen containing compound) 2. Sources: diet (beer or fish), supplements, or body produced 3. Stored in muscle as creatine (1/3) & creatine phosphate (2/3) 4. Excretion is ~ 2 g/day, equal to the amount synthesized and/or obtained from foo |
| Creatine Phosphate System | *Catalyzed by Creatine Kinase (CK) *5 - 10 second duration *Anaerobic *Fatigue associated with CrP depletion |
| Rephosphorylation of creatine to creatine phosphate | 1. Creatine shuttle 2. Requires oxygen 3. Takes place in mitochondria 4. Can take 1-2 minutes after very high intensity exercise to restore creatine phosphate |
| Anaerobic glycolysis | 1. The conversion of glucose to lactate in muscle under anaerobic conditions 2. Substrate is carbohydrate (glucose) 3. Glycogenolysis is the metabolic break down of glycogen to glucose |
| Lactate removal and oxidation | 1. Converted to pyruvate and metabolized aerobically 2. In the liver, converted to glucose via the Cori cycle |
| Oxidative phosphorylation | 1. Requires oxygen 2. Can use carbs, fats, and proteins as substrate 3. Occurs in mitochondria 4. Three phases 1. Preparation of substrates for aerobic metabolism (e.g. glycolysis) 2. Removal of electrons 3. Shuttle of electrons to produce |
| Oxidation-Reduction reactions (coupled) | a. Oxidation = removal of elec b. Reduction = acceptance of elec c. Common electron accepting compounds 1. NAD (nicotinamide adenine dinucleotide) 2. FAD (flavin adenine dinucleotide) d. NAD and FAD shuttle electrons into the electron transport chain |
| Free radicals (reactive oxygen species) | 1. Unpaired elec due to uncoupling of oxidation-reduction reac 2. Normal part of oxid phosphorylation 3. If antioxidant systems are overwhelmed tissues damage may occur (oxidative stress) 4. Excess oxidative stresswith aging and some chronic disease |
| Fat oxidation | 1. fatty acids used for energy= 16 or 18 carbons 2.Fats from storage ->taken up by tissues 3.For Krebs cycle-> fatty acids must go through beta ox a.mitrochondria matrix b.2-carbon segments removed and converted to acetyl CoA 4. (129 ATP) |
| Maximum oxygen consumption (VO2max) | 1. Maximum ability to consume oxygen 2. Affected by age, gender, genetics 3. Aerobic exercise training has substantial influence 4. Expressed as ml/kg/min 5. General categories (e.g. health/fitness or well trained) established |
| Oxygen consumption | 1. Submaximal exercise a. Oxygen consumption increases at onset of exercise b. Some “lag time” before reaching steady state c. Oxygen deficit d. Post-exercise oxygen consumption (EPOC) |
| Integration of carbohydrate, fat, and protein metabolism *Absorption state | a. Influence of insulin b. Glucose is used for immediate energy c. Glucose is stored as glycogen for future energy d. Fat is stored for future energy |
| Integration of carbohydrate, fat, and protein metabolism *In post-absorptive state | a. Influence of hormones other than insulin b. Liver glycogen is broken down to provide glucose to the blood c. Fat is released from storage |
| Carbohydrates | 1. Moderate to intense exercise 2. Found in food as sugars, starches, and cellulose 3. Found in the body as glucose and glycogen 4. Training depletes CHO stores and must be replenished 5. CHO needed before, during and/or after exercise |
| Polysaccharides | a. Chains of glucose b. Starch, fiber, glycogen c. Fiber is indigestible 1.When whole grains are processed, fiber is removed 2.Good sources of fiber: whole grains, legumes, seeds, fruits, vegetables |
| Digestion | 1. Begins in the mouth and stomach 2. Predominantly occurs in the small intestine 3. Starches are broken down to glucose 4. Disaccharides are broken down to monosaccharides by specific enzymes |
| Glucose Absorption | 1. Carrier dependent 2. Active transport 3. Portal vein to liver, circulates in blood |
| Fructose Absorption | 1. Carrier dependent, limited number of carriers 2. Concentration gradient 3. Portal vein to liver 4. Trapped in liver and converted to glucose |
| Regulation of blood glucose | 1. Normal range: 70-110 mg/dl 2. Homeostasis (equilibrium) is hormonally controlled 3. Insulin secreted in response to hyperglycemia 4. Glucagon secreted in response to hypoglycemia a. Hypoglycemia: < 50 mg/dl |
| Immediate use of glucose for energy | 1. Depends on energy need of cell and enzymatic capability 2. Red blood cells must use glucose (no mitochondria) 3. Fast-twitch muscle fibers prefer to use CHO via anaerobic glycolysis 4. Slow-twitch muscle fibers prefer to use CHO via aerobic metaboli |
| Glucagon | a. Stimulates break down of liver glycogen b. Stimulates gluconeogenesis |
| Epinephrine and norepinephrine | a. Stimulates glycogen breakdown b. Stimulates gluconeogenesis |
| Cortisol | Stimulates amino acid break down and gluconeogenesis |
| Carbohydrate loading | “Classical” approach was to severely deplete and then replete “Modified” approach eliminates severe depletion stage. General recommendation: 10 g/kg/day 3 days prior to event |
| Effects of inadequate total carbohydrate intake on training and performance | .Most athletes do not meet CHO recommendations .Insufficient CHO intake leads to low muscle glycogen levels .Acute and chronic fatigue from low CHO intake .Adequate CHO:reduce risk for immune system suppression |
| Recommended total daily carbohydrate | 45-65% of total energy intake |
| Fiber recommendation | 25 g daily for females; 38 g daily for males |
| Sugar intake and artificial sweeteners | a.High sugar intake may increase risk for some chronic diseases (controversial) b.High use of high fructose corn syrup is a concern c.Safety of artificial sweeteners has always been controversial |
Created by:
sleith87
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