3. Physiology
        3.10. Muscle
            3.10.1. Muscle structure
                3.10.1.1. Skeletal muscle
3.10.1.1.1. Skeletal muscle tension

Skeletal muscle tension

Contractile mechanism does not have a refractory period like action potential.

 

Summation of contractions

Repeated stimulation before relaxation has occurred produces additional activation of contractile elements and adds to the contraction already present.

Tetanus (tetanic contraction)

Rapidly repeated stimulation produces activation of the contractile mechanism before ANY relaxation has occurred, and individual responses fuse into one continuous contraction

 

Complete tetanus - no relaxation between summated stimuli

Incomplete tetanus - some incomplete relaxation between summated stimuli

 

Treppe

When a series of maximal stimuli is delivered to skeletal muscle at a frequency JUST BELOW the tetanising frequency, there is a gradual increase in each successive tension developed until the tensions developed reached a steady level.

Also occurs in cardiac muscles.

Thought to be due to increased availability of Ca2+ intracellularly.

 



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