What must be true of the concentration of potassium and sodium inside the neuron? Why can some ions move across membranes but others cannot? How would permeability change if types of channels in a neuron change? What is the purpose of having leak and gated channels for the neuron? What are the charges both inside and outside of the neuron before you click the stimulate neuron button? What are the charges both inside and outside of the neuron after the simulation is complete? What happens to the charge during the stimulation? What happens after the gated channels close? How many potassium ions move into the cell while how many sodium ions move out of the cell? What does the yellow line represent that runs along the neuron?