Exercise Physiology Exam 1 Study Guide1. Differentiate between aerobic and anaerobic metabolism- aerobic metabolism: o requires O2o must occur in the mitochondriao produces large amounts of energyo kicks in about 2-4 minutes after exercise begins, when anaerobic metabolism has produced as much energy as it cano end product is pyruvateo uses glucose to form Acetly CoA (Krebs cycle)- anaerobic metabolism: o no oxygen requiredo used for short bursts of exercises (after about 4 minutes of exercise)o ATP-PC system and anaerobic glycolysiso takes place in cytoplasm (anaerobic glycolysis)2. What is ATP? How does it function? How is it formed?- ATP: adenosine triphosphate; only energy currency used for muscular contractiono stored in the myofilaments of muscleo energy is released when ATP is converted to ADPo ATP ↔ ADP + Pi + Energyo only gives 2-4 seconds of power/energy - CP: creatine phosphate (PC); used after immediate ATP is used upo CP ↔ Cr + Pi + Energyo energy from this reaction helps to resynthesize more ATPo ATP/PC system is immediate energy system3. Describe glycolysis.- glycolysis: generates energy from glucose both aerobically and anaerobically; almost all reactions that take place in glycolysis are reversible - anaerobic glycolysis: no oxygen necessessary, occurs in the cytoplasmo start with blood glucose (G6P) or glycogeno releases energy that allows Pi to be recombined with ADP to create more ATPo also called lactic acid system, because lactic acid is the end producto glycogen is the stored form of glucoseo 2 lactates are produced at the end of the process, from pyruvic acid (lactate is what pyruvic acid forms in the absence of oxygen)o the ATP yield of anaerobic glycolysis if using glycogen, and 2 ATP if the process starts with blood glucoseo also, 2 NADH and 2 NAH are formed as well NAD is a transporter (oxidation-reduction reactions)- aerobic glycolysis: requires oxygen, occurs in the mitochondriao the end product is pyruvate, but in the presence of oxygen Acetly-CoA is formed, instead of lactateo same amount of ATP are yielded in each form of glycolysiso in the process that follows aerobic glycolysis, the Krebs Cycle, more ATP are formed- lactate: can also be formed during rest and moderate exercise, but only a small amounto two ways: 1) energy metabolism of RBCs that contain no mitochondria, and 2) limitations posed by enzyme activity in muscle fibers with high glycolytic capacityo but this is readily oxidized for any neighboring muscle fibers or other distant tissues like the heart and ventilatory muscles4. Describe the Krebs Cycle- entry point to the Krebs cycle is Acetyl-CoA created from pyruvate in aerobic glycolysis- also called the citric acid or TCA cycle- pyruvate joins with CoA to form acetyl-CoA, and the two released H+ transfer their electrons to NAD+ to form one molecule of CO2- Acetyl-CoA creates 6-carbon citric acid, and the cycle ends with a 4-carbon oxaloacetate, which then combines with acetyl-CoA again to repeat the cycle over and over again- 3 NADH molecules are formed, 2 CO2 molecules are formed, 1 FADH2, 1 ATP per Acetyl-CoA (2 molecules enter the cycle), and 20 total H+ are released in the citric acid cycle5. Describe the Electron Transport Chain - happens in the mitochondria- energy is released, from high energy to low energy- happens at the same time the citric acid cycle is occurring- FADH in the ETC gives 2 ATP, while NADH gives 3 ATP- 12 H2O is produced at the end of the ETC- in total, 32 molecules of ATP are produced from the oxidation of one molecule of glucose in aerobic glycolysis, the Krebs cycle, and ETC6. Beta Oxidation - fat is a much larger source of fuel compared to glucoseo 30% more energy/ATP than CHOso fats: 9 calorieso CHOs: 4 calories- high amounts of ATP are stored in fat- body likes to use fat as fuel for sub-maximal exercises- fat is stored in adipocytes- oxygen must be available for fat to be used as a fuelo breakdown of triglyceride to three free fatty acidso free fatty acids transported in blood to the muscle mitochondria, where they are prepared for catabolism (energy activation)o breakdown of fatty acid to acetyl-CoA through beta oxidation and NADH and FADH2 are producedo coupled oxidation in citric acid cycle and electron transport chain- lactic acid inhibits fatty acid mobilization- beta oxidation: the process of breaking down a fatty acid to create a molecule of acetyl-CoA,which takes place in the mitochondriao continues/repeats until the entire fatty acid molecule degrades to acetyl-CoA for direct entry into the citric acid cycle until only 2 2-carbon molecules, or a 2-carbon and a 3 carbon molecule, are lefto oxygen must join with hydrogen for beta oxidation to proceedo fat catabolism is halted under aerobic conditions because hydrogen remains with FAD and NAD+o produces NADH and FADH2 by cleaving the fatty acid into 2-carbon acyl fragmentso 5 ATP produced by each round beta oxidation (each acetyl-CoA produced or each 2-carbons removed), plus 12 from Krebs cycle = 17 ATPo for each 18-carbon fatty acid that goes through beta oxidation and Krebs cycle metabolism, about 147 ATP are produced, and for one triglyceride molecule, this means 441 ATP are yielded this shows that fat catabolism produced much more energy than glucose metabolism7. What is the respiratory quotient and how is it determined? What is the relationship between the respiratory quotient and fuel use?- the more O2 you consume, the more CO2 you produce, but eventually you reach a ceiling- R = VCO2/VO2- RQ for fat: 0.71- RQ for CHO: 1.0- a graph of R vs VO2 shows the contribution of fuel to energetico what fuel you are using at what type of activity (rest, high intensity, etc)o closer you get to max, the more CHO you use and less fats you useo max amount of fats are used as a fuel at about 50% VO2- as you train, you are better able to manage lactic acid (you have a better buffering capacity)8. What is the primary fuel for different types of activities?- resto systems used: aerobico substrates used: about equal amounts (50%) of fats and CHO usedo lactate product: minimalo O2 consumption: 150-350 mL per minute- max, all-out effort for 2-3 minuteso energy systems: ATP-PC, anaerobic glycolysis, and some aerobic if necessaryo substrates: ATP, PC, glycogeno lactate: high, because it depends a lot on using glycogen for fuelo O2 consumption: large oxygen deficit present because the level of O2 consumed is below that
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