<span>A mirror neuron is a neuron that fires both when an animal acts and when the animal observes the same action performed by another. Thus, the neuron "mirrors" the behavior of the other, as though the observer were itself acting. Such neurons have been directly observed in primate species.</span>
        
             
        
        
        
Tough one would have been expressing another way?
        
             
        
        
        
Answer:
Once the sodium channels opens and sodium is allowed to diffuse freely in and out of the cell, this will cause a large change in entropy and enthalpy. Values for both these quantities will increase significantly, however, the change in free energy will be small when we compare the open and closed state of the sodium channel. With regards to the stability of the system, it will reach equilibrium because the concentration of sodium ions is being allowed to diffuse without any regulation. 
Hope that answers the question, have a great day!