Twitch Contractions Flashcards
Describe a motor unit.
One motoneuron + muscle fibres.
What is the difference between tension and load?
Tension - force exerted by muscle.
Load - force exerted on muscle.
Define isometric, isotonic and lengthening.
Constant / decreasing / increasing length.
Define the latent period.
The time before excitation-contraction coupling starts.
Define the contraction time.
Between the start of tension and peak tension (dependent on [Ca2+]).
As _____ increases, _____ _____ and _____ _____ decreases.
1 - load.
2 - contraction velocity.
3 - distance shortened.
Compare isotonic and isometric contraction.
Isotonic - longer latent period, shorter contraction time.
Explain how summation of APs occur.
A single AP stimulates a muscle fibre and causes a twitch contraction. APs can occur in a short space of time.
Describe unfused and fused tetanus.
Explain how tetanus occurs.
Partial and complete summation.
[Ca2+] never gets low enough for tropomyosin and troponin to block myosin binding sites, so contraction occurs for a long period of time.
How does filament overlap affect tension?
Too much overlap - filaments interfere with one another.
Too little overlap - less tension.
Optimal length - greatest isometric tension.
