What is a chemical synapse? Slow, but access many neurons at once
Slow, but easier to control
Immediate, but accesses one neuron
Immediate, but easy to control

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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where in your body is there an enzyme that does function at a high or low ph? what is the name of that enzyme and its function?