BIOL 404-Exam 4-Muscle 4

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What is an Isometric twitch?

Generates tension but does not shorten
What is an isotonic twitch?

Generates tension and shortens the muscle
What type of load shortens the fastest (i.e. has a steep load-shortening relationship)?
- Light load
What type of load shortens the slowest (i.e. has a shallower load-shortening relationship)?
- Heavy load
The shortening velocity is a function of what?
- The load
When does a lengthening contraction occur?
- After the maximum isometric tension has been reached
Between what two points on a load-velocity curve can the muscle perform isotonic contraction (shorten)?
- Between the Maximum shortening tension and the Minimum shortening tension
How long does a single action potential is skeletal muscle last?

1-2 ms
How long may a single muscle twitch last?

100 ms
During the period of contractility can a second action potential be initiated?

Yes (contractility is still occurring, but the last action potential has dissipated)
What happens when a stimulus is applied to a muscle fiber while it is still contracting?

It induces a contractile response with a higher peak tension than a single twitch
How can the peak tension of a muscle contraction be raised?

By applying another stimulus before contraction has ceased
What is the term for the increase in the mechanical activity from successive action potentials?

Summation
What is summation?

The increase in mechanical activity due to successive action potentials
What is tetanus (tetanic contraction)?

A maintained contraction due to repeated stimulation
What is the term for a sustained contraction due to successive stimulation?

Tetanus or Tetanic contraction
What is unfused tetanus?
- Repeated stimulus leading a high undulating tension level
What is the term for a high undulating tension produced by repeated stimulus?

Undulating tension