Describe the phases or periods in a nerve impulse.

Question

What will be an ideal response?

Answer 1

Ans: During the resting potential, the neuron maintains a steady negative charge. If depolarization occurs, sodium channels will open. When a threshold is reached, an action potential occurs, characterized and an opening of all sodium channels and entrance of sodium channels. The charge inside the cells shift from negative to positive. After a brief period of time, the local potential returns to rest state levels, but slightly hyperpolarized. This period is called a refractory period, first consisting of a phase where no stimulation can cause an action potential (absolute) and then by a phase where greater stimulation is needed (relative) to produce an action potential.