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how does neuron works
Neurons conduct electrical impulses by using the Action Potential.Neurons, like all cells, maintain different concentrations of certain ions (charged atoms) across their cell membranes. They pump out positively charged sodium ions and they pump in positively charged potassium ions. Thus there is a high concentration of sodium ions present outside the neuron, and a high concentration of potassium ions inside. The neuronal membrane also contains specialised proteins called channels, which form pores in the membrane that are selectively permeable to particular ions. Thus sodium channels allow sodium ions through the membrane while potassium channels allow potassium ions through.
 Now, under resting conditions, the potassium channel is more permeable to potassium ions than the sodium channel is to sodium ions. So there is a slow outward leak of potassium ions that is larger than the inward leak of sodium ions. This means that the membrane has a charge on the inside face that is negative relative to the outside, as more positively charged ions flow out of the neuron than flow in. This difference in the concentrations of ions on either side of the membrane gives rise to the membrane potential and the membrane is said to be polarised.
There is a pressure for the sodium ions to enter the neuron, but they are prevented from doing so by the membrane and the pumping mechanisms that remove any ions that manage to get in. 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. Thus, there is first an influx of sodium ions (leading to massive depolarization) followed by a rapid efflux of potassium ions from the neuron (leading to repolarisation). Excess ions are subsequently pumped in/out of the neuron.

This transient switch in membrane potential is the action potential. The cycle of depolarization and repolarization is extremely rapid, taking only about 2 milliseconds (0.002 seconds) and thus allows neurons to fire action potentials in rapid bursts, a common feature in neuronal communication.
The sodium channels in the neuronal membrane are opened in response to a small depolarization of the membrane potential. So when an action potential depolarizes the membrane, the leading edge activates other adjacent sodium channels. Thus a wave of depolarization spreads from the point of initiation.Action potentials move in one direction. This is achieved because the sodium channels have a refractory period following activation, during which they cannot open again. This ensures that the action potential is propagated in a specific direction along the axon.
 The speed of action potential propagation is usually directly related to the size of the axon.
Myelin is the fatty membranes of cells called Oligodendroglia (in the CNS) and Schwann Cells (in the PNS) that wraps around the axon and acts as an insulator, preventing the dissipation of the depolarisation wave. The sodium and potassium ion channels, pumps and all the other things  associated with action potential propagation are concentrated at sites between blocks of myelin called the Nodes of Ranvier. This myelin sheath allows the action potential to jump from one node to another, greatly increasing the rate of transmission.


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