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How do skeletal muscles contract?
1. action potential is initiated by the firing of a motor neuron
2. depolarization of the motor nerve ending releases ACh
3. ACh diffuses across synaptic cleft and binds to membrane receptors
4. membrane channels open and allow Na
to enter the muscle cell
5. entry of Na
shifts membrane potential in a positive direction and polarization occurs
What triggers a skeletal muscle contraction?
generation of an action potential on the sarcolemma
What's different about smooth muscle contractions?
brought about by variable stimuli
contraction is much slower
What's different about cardiac muscle contractions?
don't require nerve stimulation but still need an AP
AP slower than in skeletal muscles
contraction time and AP are the same
animal anatomy & physiology