Blood cells are produced in which system?
a. circulatory system
b. immune system
c. skeletal system
d. endocrine system
user:
heart disease includes all of the following risk factors except
a. high blood pressure
b. high cholesterol levels
c. cigarette smoking
d. regular exercise

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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