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Karteikarten von alexlpeart, aktualisiert more than 1 year ago
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Erstellt von alexlpeart
vor etwa 11 Jahre
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| Frage | Antworten |
| Give an explanation as to why decreasing pH in the muscle might decrease force. Give some evidence as to why this cant be the only factor affecting fatigue. | Low pH interferes with conversion of electrical signal to mechanical signal in the sarcoplasmic reticulum therefore decreasing Ca+ release and Ca+ dependent Ca+ uptake. However when muscle placed in acidic conditions mas muscle force only fell by 30% so there must be other factors. |
| Glycolysis is affected by ____ as hexokinase and PFK are inhibited. | acidosis |
| Give some evidenced to suggest why PCr decrease is not the reason for fatigue? | PCr stores recover before force. |
| Give a good indicator of fatigue. | ATP : ADP ratio |
| As we exercise Pi _____. This _____ the action of cross bridge cycling so muscles move to a low ____ state when Pi is high. | Increases, inhibits, force |
| Describe what happens when we maximally stimulate fatigued muscles compared to sub maximal stimulation. | Sub maximal stimulation cant activate the muscle to the same level as we would expect in non fatigued muscled. however maximal stimulation still produces a maximal contraction. |
| What does increasing the stimulation frequency do in relation to calcium ions | Increased frequency of stimulation means increased time Ca+ in the muscles for the same amount released. This is just because Ca+ is absorbed slower. |
| When we are fatigued we need _____ stimulation for the same sub maximal force. | Greater |
| When we are fatigued we need _____ stimulation for the same sub maximal force. | Greater |
| When we are fatigued but can still create maximal contraction force, what does this show about the muscle structure? | The cross bridge proteins are not damaged |
| If we can still create maximal force, why do we encounter problems with fatigued muscle in every day life? | Sub max contractions wont produce enough force for the task if we don't accommodate for fatigue. e.g. picking up a suitcase we might not put enough force the first time so wont be able to pick it up. We need to try again with greater activation in order to overcome the fatigue problem. |
| Give some evidence that low frequency fatigue is not due to excitation failure. | We still see an M wave. |
| What is the cause of low frequency fatigue? | reduced Ca+ released per action potential, so we need higher stimulation for the same Ca+ release. |
| What kind of exercise are we most likely to experience low frequency fatigue? What is the result of low frequency fatigue is the proceeding days? | unaccustomed exercise and eccentric exercise. We experience DOMS after low frequency fatigue |
| What happens to the relaxation in muscles experiencing low frequency fatigue? | maximal relaxation decreased and increased relaxation time. |
| Give reasons why Ca+ energetics are unlikely to explain slowing of muscle relaxation. Suggest alternative reasons. | slower Ca+ uptake would result in Ca+ remaining high for longer however cross-bridge sensitivity to Ca+ decreases countering the increased Ca+ in the muscle so unlikely to explain slower rate of relaxation. Might be due to decreased rate off cross bridge dissociation. |
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