Peripheral Fatigue Flashcards
What is the difference between fatigue and weakness?
Fatigue is failure to maintain required force, weakness is failure to generate it
How can we determine whether fatigue is located centrally or peripherally?
Using electrical stimulation, if the muscles can redo the exercise after, the fatigue must be central
Type I vs Type II fibres
- Type II fatigue quicker
- Type I are essentially unfatigable
- Calcium conc. decrease as the number of contractions increase in type II, in type I decreases a lot slower
How does caffeine effect calcium release?
Opens ryanodine receptors in the sarcoplasmatic reticulum membrane, releasing calcium
True/False: Accumulation of lactate can be useful for performance
True, it can be oxidised by a number of tissues and/or be converted to glycogen in the liver
Which of the following are NOT important considerations in the explanation of peripheral fatigue?
- Ca2+
- Na+K+ ATPase activity
- Serotonin Synthesis
- SR ATPase activity and Ca2+ uptake
- Serotonin Synthesis, this is important in central fatigue not peripheral.
Which of the following is NOT a site of peripheral fatigue?
- Actin-myosin filaments
- Spinal cord
- Transverse tubular system
- Sarcoplasmic reticulum (SR)
- Spinal Cord
How does calcium release cause contraction?
- Brain sends an electrical signal via motor neurones to the fibres
- The action potential spreads across the cell membrane and down the T-tubules
- The action potential excites the sarcoplasmic reticulum, releasing calcium
- The calcium binds to troponin moving tropomyosin away from actin’s binding sites
- Myosin heads attach and pull the actin
Why when fatigued does it take longer for the muscle to relax?
It takes longer to uptake the calcium
True/False: During fatigue it takes longer for the Sodium-Potassium pump to restore the resting potential of a cell
True, meaning it takes longer to produce force
True/False: Accumulation of Potassium ions makes it easier to induce action potentials
False
True/False: Fatigue is associated with high inorganic phosphate
True
How can inorganic phosphate cause fatigue?
It binds with free calcium reducing the amount for contractions
True/False: ATP in a cell doesn’t drop below 60% of resting levels (whole muscle) however in isolated fibres it can drop to 20%
Whole muscle
True
What does compartmentalisation suggest?
Metabolite concentrations vary within different compartments of the cell
