What is depolarization?

Nerve cells have a negative electric charge across plasma membranes known as resting potential. The plasma membrane is a thin border layer that closes the nerve cell, and there is a resting potential because the inside of the cell is negatively charged compared to the outside. When a neurotransmitter, a chemical that carries signals between the nerve cells, arrives on the membrane or the membrane is disturbed mechanically, the charge over the membrane and becomes more positive. This change is known as depolarization, and if it reaches a certain level, what is called the results of the action potential where electrical pulse is transmitted along the nerve. After action potential, the membrane is repolarized, re -charged and restores resting potential. There is a potassium inside the cell and more sodium outside the cell. The reason is the sodium pump and position in the cell membrane, which actively moves sodium from the cell and potassium to the cell.

There are channels in the membrane, through which sodium and potassium ions can travel, but when the membrane is calm, the sodium channels are closed and only some of the potassium channels are open. Sodium ions are forced to stay outside the cell, while some potassium ions escape from the cell to connect to them with open channels. The net result is that more positively charged ions ends outside the cell than inside, and this creates a negative charge over the membrane, known as resting potential, which is necessary to depolarize neurons.

For the action potential to take place, the nervous cell must first be stimulated by stretching or the neurotransmitter. The depolarization effect then occurs because sodium channels open and allow sodium to the cell, increasing the number of positive ions inside and increasing the more positive electrical potential through the membrane. Once the depolarization reaches the threshold, many sodium channels open at once and run outThe action potential, where there will be a sudden membrane depolarization, with depolarization also passing along the nerve cell in the wave.

After depolarization, repolarization occurs after a short interval known as the refractory period. During this period, another stimulus applied to the cell has no effect. The refractory period only takes a fraction of a second, allowing nerves to shoot many times in the area of ​​one second. Repolarization includes potassium ions from the cell first than sodium actively pumped. As soon as the membrane potential reaches the necessary negative charge and the nerve is ready to shoot again.