An open system is different than a closed system because open systems do not freely exchange energy and matter with its surroundings. closed systems do not exchange energy with its surroundings. closed systems freely exchange energy and matter with its surroundings. open systems freely exchange energy and matter with its surroundings.

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.  

read more on -