Nerve impulse
When a neuron is not conduction or is in resting state the axonal membrane is more permeable to K+ ions and impermeable to Na+ ions. The sodium potassium pump actively pumps out 3Na+ ions to the extracellular fluid and takes in 2K+ ions into the cell. Due to the imbalance in charge, a potential difference is developed across the axonal membrane, also known as the resting potential (-70mV). The outer side of the membrane will have a positive charge while the inner side will have a negative charge.