To it, then the action potential would propagate in all directionsĪlong an axon.
Thus a wave of depolarization spreads from the point of initiation. The leading edge of which activates more adjacent sodium channels. This leads to another spike of depolarization Potential depolarizes the membrane, the leading edge activates otherĪdjacent sodium channels. To a small depolarization of the membrane potential. The sodium channels in the neuronal membrane are opened in response The cycle of depolarization and repolarization isĮxtremely rapid, taking only about 2 milliseconds (0.002 seconds)Īnd thus allows neurons to fire action potentials in rapid bursts,Ī common feature in neuronal communication. This transient switch in membrane potential is the action Ions are subsequently pumped in/out of the neuron. Potassium ions from the neuron (leading to repolarisation). Ions (leading to massive depolarization) followed by a rapid efflux of Has the effect of opening the potassium channels, allowing potassium
Into the neuron, and making the inside of the cell momentarily positivelyĬharged - the cell is said to be depolarized. The sodium channels are opened, positively charged sodium ions flood Mechanisms that remove any ions that manage to get in. Similarly, there is a pressure for the sodium ions to enter the neuron,īut they are prevented from doing so by the membrane and the pumping Side, the rate at which water flows into the boat in massively increased. Is a pressure for water to enter and if a big hole is punched in the 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. Relative to the outside, as more positively charged ions flow out That the membrane has a charge on the inside face that is negative Is larger than the inward leak of sodium ions. So there is a slow outward leak of potassium ions that More permeable to potassium ions than the sodium channel is to sodium Now, under resting conditions, the potassium channel is Sodium ions through the membrane while potassium Which form pores in the membrane that are selectively permeable to
The neuronal membrane also contains specialised Sodium ions present outside the neuron, and a high concentration of To the gardeners out there!!) Thus there is a high concentration of Neurons do the same thing, but they pump out positively charged sodium In order to keep the boatĪfloat, the small amount of water entering through the leak has toīe pumped out, which maintains a lower water level relative to the Imagine the case of aīoat with a small leak below the water line. Of certain ions (charged atoms) across their cell membranes. Neurons, like all cells, maintain different concentrations
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