Lab III. - Questions Flashcards
Give the steps in making isometric maximum curve
Supramaximal single stimuli and provide isotonic conditions in each step
What is the electromyogram (EMG)?
Potential differences from muscle contraction measured on the skin
When does complete tetany develop?
When muscle does not relax but show continous tonic spam
Maximal stimulus?
The weakest stimulus that just causes complete contraction
Give the steps and principle in passive stretch curve to measure muscle function?
relative lenght determind by different weights
What happens when Ca binds to TnC?
Shift tropomyosin-troponin complex to the groove of the actin filament
Which muscle, and which nerve is used in the classical frog-nerve experiment?
m. gastrocnemius and sciatic nerve
Explain the importance of the muscle reacting to different threshold potentials?
the “all-or-none” law of the muscle fibres
All or none law?
An adequate stimulus causes maximal contraction (if threshold is reached)
Physiological reason for muscle fatigue?
Increasing concentration of metabolic by-products
Steps of “cross the bridge” cycle?
Formation of actomyosin complex, sliding of filament and dissociation of ATP-dependent terminal phase
Latency period?
The time period between the stimulation and the start of contraction
What is meant by temporal summation?
Superposition
What is length tension curve?
Diagram with passive stretch curve, isotonic max curve and isometric max curve
Which muscle exhaustes latest?
red muscles with slow-twitch fibres
What is superposition?
Repeated stimulation before previous calcium transient has finished, give additional calcium release and increased contraction
The three curves in measuring lenght-tension?
passive stretch curve, isotonic max curve and isometric max curve
Brief explain the passive strech curve?
Relative length of muscle for each weight
Red muscle?
oxidative with slow-twitch fibres
White muscle?
glycolytic with fast-twitch fibres
Which ion increases in the myoplasm as the action pot. reaches the muscle?
Calcium
How do we find the minimal stimulus of a muscle?
Increase stimulus strenght gradually between 0 and 500 mV
What is minimal stimulus?
the weakest stimulus that just causes complete contraction
