4. What are the 4 main constituents of blood?

if you are asking about the types of blood the there is O, A, B, and AB together

Explanation:

answer; i believe the correct answer is ( proteins );

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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