EVERYDAY SCIENCE

Detailed explanation-1: -A stimulus first causes sodium channels to open. Because there are many more sodium ions on the outside, and the inside of the neuron is negative relative to the outside, sodium ions rush into the neuron. Remember, sodium has a positive charge, so the neuron becomes more positive and becomes depolarized.

Detailed explanation-2: -During the depolarization phase, the gated sodium ion channels on the neuron’s membrane suddenly open and allow sodium ions (Na+) present outside the membrane to rush into the cell. As the sodium ions quickly enter the cell, the internal charge of the nerve changes from-70 mV to-55 mV.

Detailed explanation-3: -In neurons, the rapid rise in potential, depolarization, is an all-or-nothing event that is initiated by the opening of sodium ion channels within the plasma membrane.

Detailed explanation-4: -The Action Potential However, if the sodium channels are opened, positively charged sodium ions flood into the neuron, and making the inside of the cell momentarily positively charged-the cell is said to be depolarized. This has the effect of opening the potassium channels, allowing potassium ions to leave the cell.

Detailed explanation-5: -The resting membrane potential is approximately-70 mV, so the sodium cation entering the cell will cause the membrane to become less negative. This is known as depolarization, meaning the membrane potential moves toward zero (becomes less polarized).