A stimulus causes a change in permeability of neural membranes . w process of transmitting an impulse . If the stimulus reaches neuron , an action potential is generated . Select occur once the threshold potential is reached . neural membranes , which begins the the stimulus reaches the threshold potential of a is generated Select the numbers of the statements below that 1. Sodium ions flow into the neuron . 2. Sodium ions flow out of the neuron . 3. The membrane potential becomes positive. 4. The membrane potential becomes negative. 5. Voltage -gated potassium channels open. 6. Voltage - gated potassium channels close . 7. Potassium ions flow into the neuron . 8. Potassium ions flow out of the neuron .                                           Place the numbers in order from the first event to the last event :