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outline 14
Comparative Physiology- Renner Lecture 14
| Question | Answer |
|---|---|
| how are muscle fiber types classified? | based on myosin ATPase isoform present in the fiber and the types of metabolic pathways that predominate in the cell |
| weightlifting increases density of_________________ due to ___________________ | muscle fibers, actin myosin |
| endurance training increases number of ________________ to increase capacity to produce _____________ | mitochondria, ATP |
| what are two types of muscle fiber types? | slow oxidative fibers fast oxidative fibers fast glycolytic fibers |
| what are some features of slow oxidative fibers ? | low myosin ATPase activity rich in mitochondria high concentration of myoglobin |
| what is a feature of slow oxidative fiber that contribute to it being rich in mitochondria? | rich blood supply |
| why are slow oxidative fibers good for O2 loading and transport? | high concentrations of myoglobin |
| what fibers help support posture? | red fibers in slow oxidative fiber types |
| what are some features of fast oxidative fibers? | high concentration of myosin ATPase rich in mitochondira high myoglobin concentrations |
| slow oxidative fibers hydrolyze about ________ ATPs per sec and fast oxidative fibers hydrolyze about ________ ATPs per sec and | 300,600 |
| what contributes to fast oxidative fibers being resistant to fatigue? | higher concentrations of myosin ATPase, higher cycle of muscle contractions, and more ATP hydrolyzed per sec |
| fast oxidative fibers differ from slow oxidative fibers due to the presence of ____________________fibers which can generate more ___________ than slow oxidative | fast glycolytic, tension |
| what are fast oxidative fibers used for? | repeated movement–walking, running at an even pace |
| Fast glycolytic fibers have low levels of ATP produced by ox phos, why? | due to the low levels of mitochondria, ATP from glycolysis by anaerobic metabolism is available too |
| fast glycolytic fibers are white fibers due to the lack of ___________ | myoglobin |
| larger muscle fibers that fatigue easily that are used for rapid contractions | fast glycolytic fibers |
| fibers with low levels of ATP produced by ox phos and has low levels of mitochondria | fast glycolytic fibers |
| why is flight special? what does it require? | rapid high strength contractions that are maintained at a high frequency |
| what are the three major adaptations regarding flight? | light weight–hollow bones higher body temp– higher rate ATP synthesis+higher Ca2+ clearance rate=rate of cycling muscle contraction mitochondria have a lot more cristae to improve O2 consumption |
| how does increasing the infoldings of mitochondria affect O2 consumption | cristae is site for electron transport chain, which means it will give high energy electrons from NADH, FADH2 which are both used to synthesize ATP. This adaptation will improve efficiency of O2 consumption |
| what are the two muscle contraction types in flight? | synchronous and asynchronous |
| what does synchronous muscle contraction mean? | in flight, muscle contraction is synchronized to the firing of motor neuron that generates muscle contraction |
| what organisms use synchronous contractions? | birds and some insects |
| explain synchronous muscle contraction | it is direct. one group of muscles pull wing down and another group of muscle elevates the wing. Top speed ~100wing beats/minute in humming birds |
| how does asynchronous muscle contractions differ from synchronous muscle contractions? | asynchronous are not linked to AP directly, but require initial action potential to be generated |
| what organisms use asynchronous muscle contractions? | predominately found in insects |
| rate of asynchronous muscle contractions ? | ~1000 wing beats minute (mosquito buzz) |
| explain asynchronous muscle contractions | indirect-flight muscles do not directly attach to the wings. AP starts the cycle, releases Ca2+from SR of muscles- contractions generated by stretching respective muscles |
| what are the two muscles that control the asynchronous flight mechanism | dorsoventral muscle–wing up dorsal longitudinal–relaxed |
| contraction mechanism of dorsal longitudinal and dorso-ventral muscles | contraction of dorsal longitudinal muscle stretches the dorsal ventral muscle, that stretch will activate the contractile response in the dorsal ventral muscle.Since muscles are out of phase oscillation will result |
| why does asynchronous muscle contractions work | SR is greatly reduced, not all Ca2+ is cleared with muscle contractions , the presence of Ca2+ maintain actin-myosin cross bridges. unless another AP comes in, Ca2+ will be returned to SR |
| what are advantages to asynchronous contraction in insects? | Ca2+ATPase pump is reduced meaning less ATP required to operate pump, in turn, requiring less mitochondria to produce ATP less % of cell volume dedicated to contractile filaments (actin/myosin)-ATP produced is devoted more for cross bridge formation |
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