Depolarizations of neuronal membrane

Question

How the depolarizations of neuronal membrane start?

Answer 1

Primary cause of neuronal depolarization refers to the process of binding of neurotransmitters liberated in synapse to the specific receptors within the membrane of neuron which is obtaining the stimulus. Binding of the neurotransmitters to those receptors is a reversible method which changes the membrane permeability of region as the binding results the sodium channels to open. Whenever positive sodium ions go into the cell in favor of their concentration gradient, voltage of the membrane rises, hence, reducing the negative polarization. In case, this depolarization arrives the excitation threshold which is around –50 mV, the depolarization continues, the action potential is achieved and  impulse is transmitted all along the cell membrane.