Leaky sodium channels allow sodium to diffuse into the cell.

The interior of the neuron is at -70mV relative to the outside.

The sodium-potassium pump forces 3 sodium ions outside of the cell and 2 potassium ions inside of the cell, against each ion’s concentration gradient.

There are large negatively charged proteins inside the cytoplasm.

There is a concentration imbalance of potassium with more present outside the cell.