Do muscle fibers themselves have absolute and relative refractory periods? I know neurons do, but does the actual muscle fiber?
Muscle Refractory period
- Thread starter kfcman289
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No, the nervous impulses can keep the voltage gated calcium channels open allowing continuous contraction of muscle. (Or) the next impulse that opened the channel would occur before the calcium was depleted enough to unbind from troponin.
The muscle would eventually run out of ATP.
Tetanus toxin would show muscles not having a refractory period. (if i understand the question)
The muscle would eventually run out of ATP.
Tetanus toxin would show muscles not having a refractory period. (if i understand the question)
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What DrknoSDN is referring to in "continuous contraction of muscle" is the summation of stimuli. When you have maximal summation, you reach maximum tension of the muscle in something called "tetanic contraction". Incomplete or "unfused" tetanus refers to stimulation of the muscle fiber where the fiber relaxes slightly between stimuli. This is illustrated in figure C below. In contrast, "Fused" or complete tetanus refers to continuous contraction where no rest is observed. This is illustrated in figure D in the picture below. Also notice how the muscle fatigues as DrknoSDN pointed out.
The tetanus toxin blocks the release of inhibitory neurotransmitters that would otherwise inhibit continual contraction of the muscle, and therefore the muscle stays contracted. This is why you may have heard of "lockjaw" being associated with tetanus. This info. isn't on the AAMC guide though, so I wouldn't worry too much about it for now.
