intro to physio
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how do mucle cells generate ATP at rest?
catabolize fatty acids
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
what happens during muscle contraction?
cross-bridge breaks down ATP into ADP and a phosphate group; CP then recharge ATP
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
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
what is metabolised during moderate activity in aerobic environment?
glucose and fatty acids
during peak acitivity, how are most ATP produced in anerobic environment?
through glycolysis with lactate and hydrogen ion as by-products
how many products are formed from CP reaction?
1 ATP per CP, creatine
how many products are formed from aerobic respiration?
38ATP per glucose, CO2, H2O
how many products are formed from anerobic respiration?
2ATP per glucose, lactic acid
why does your body switch to fatty acids in the generation of ATP?
to make sure your brain has enough glucose to function
what is muscle fatigue?
inability of muscle to maintain force of contraction after prolonged activity (rarely achieved)
what is muscle fatigue caused by?
depletion of energy reserves or a lowering of pH due to lactic acid build up
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
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
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
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
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
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
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
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)
reverse trichrome stain
mitochondria appear as red graular areas, especially prominent in the subsarcolemmal regions of the fiber
ATPase reaction stain, how does type 1 and type 2 compare?
oxidative reaction stain (type 1, type 2)
- type 1 very dark
- type 2 inermediate or light
variable staining of fibers reflects glycogen content and crudely approximates fiber type distribution
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