AP PSYCHOLOGY

Detailed explanation-1: -The resting potential is the state of the membrane at a voltage of −70 mV, so the sodium cation entering the cell will cause it to become less negative. This is known as depolarization, meaning the membrane potential moves toward zero.

Detailed explanation-2: -[5] Depolarizing current from an action potential travels very rapidly through the cytoplasm of axons, insulated by myelin until reaching the next node of Ranvier. At each node, the membrane depolarizes above the threshold voltage, and the influx of sodium ions again initiates the action potential through Nav.

Detailed explanation-3: -When the depolarization reaches about-55 mV a neuron will fire an action potential. This is the threshold. If the neuron does not reach this critical threshold level, then no action potential will fire.

Detailed explanation-4: -Depolarization is caused by a rapid rise in membrane potential opening of sodium channels in the cellular membrane, resulting in a large influx of sodium ions. Membrane Repolarization results from rapid sodium channel inactivation as well as a large efflux of potassium ions resulting from activated potassium channels.