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Grumblepanda t1_j4luxop wrote

Reply to comment by goosebattle in Why are skeletal muscle fibres bundled? by Repulsive_Cry_2200

Contrary to the instructor who once said there is only "On or Off" for muscle engagement. I really hope I misunderstood their intention with that.

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goosebattle t1_j4m0zj0 wrote

Motor units (and single muscle cells) are almost operating as on/off. There is some minor modulation possible with changes in firing frequency. Each muscle has many (typically >>100) motor units varying in size, each with an on/off switch. The net result of having so many motor units is the muscle behaves as if it is operating with a dimmer switch.

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