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xijunzhu
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how do mucle cells generate ATP at rest?
catabolize fatty acids
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what are the ATP used for at rest during muscle metabolism?
- some are held in reserve
- some used to transfer high energy to creatine forming creatine phosphate
- create glycogen
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what happens during muscle contraction?
cross-bridge breaks down ATP into ADP and a phosphate group; CP then recharge ATP
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what is creatine phosphate used for?
- used to recharge ATP after cross-bridge breaks down ATP into ADP and a phosphate group
- ADP+creatine phosphate gives ATP+creatine
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what is the role of creatine phosphokinase? (CK or CPK?)
- regulates the reaction of ADP+Creatine phosphate gives ATP and creatine
- (lasts 15 seconds)
- not long term ATP source
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what is metabolised during moderate activity in aerobic environment?
glucose and fatty acids
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during peak acitivity, how are most ATP produced in anerobic environment?
through glycolysis with lactate and hydrogen ion as by-products
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how many products are formed from CP reaction?
1 ATP per CP, creatine
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how many products are formed from aerobic respiration?
38ATP per glucose, CO2, H2O
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how many products are formed from anerobic respiration?
2ATP per glucose, lactic acid
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why does your body switch to fatty acids in the generation of ATP?
to make sure your brain has enough glucose to function
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what is muscle fatigue?
inability of muscle to maintain force of contraction after prolonged activity (rarely achieved)
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what is muscle fatigue caused by?
depletion of energy reserves or a lowering of pH due to lactic acid build up
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how do sprinters and endurance athletes differ in their metabolism?
- sprinters deplete CP and ATP rapidly and build up lactic acid
- endurance athletes can draw on stroed glycogen and lipids
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what is the lactate threshold of muscle fatigue?
- the point where lactate production exceeds removal in blood
- maximal intensity at which steady state exercise can be maintained
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what is the oxgen debt?
the amount of oxygen the body takes in to regenerate ATP and CP, replenish O2, and convert lactic acid back to pyruvate
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what are the types of muscle fibers?
- slow fibers have extensive vasculature and myoglobin that cause them to appear reddish
- fast fibers (pale) called white muscle fibers
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why are slow oxidative fibers high resistant to fatigue?
- oxgyen supply is greater due to more perfusion
- myoglobin stores oxgen in the fibers
- oxygen use is efficient due to large numbers of mitochondria
- prefer to use fat as energy source
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what is the difference between Type 1, Type 2A and Type 2B of muscle fibers?
- Type 1: slow contraction speed and low myosin ATPase activity
- Type 2A: have medium contraction speed and high myosin ATPase activity
- Type 2B: fast contraction speed and a high myosin ATPase activity
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what are the chararcteristics of Type 2A
- progressively recruited when additional effort is required but still very resistant to fatigue
- can use either glucose or fats as source of energy
- still aerobic, more expensive to operate than Type1
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characteristics of Type 2B
- only recruited for brief maximal efforts/easily fatigued
- poor surface to volume ratio/limited capillary supply slows delivery of oxygen and removal of waste
- few mitochondria and little myoglobin (white color)
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reverse trichrome stain
mitochondria appear as red graular areas, especially prominent in the subsarcolemmal regions of the fiber
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ATPase reaction stain, how does type 1 and type 2 compare?
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oxidative reaction stain (type 1, type 2)
- type 1 very dark
- type 2 inermediate or lightÂ
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PAS stain
variable staining of fibers reflects glycogen content and crudely approximates fiber type distribution
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