Nerve Impulses

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Explain how a nerve impulse passes along a non-myelinated neuron

Below: ion pump in a plasma membrane. 

(http://click4biology.info/c4b/6/images/6.5/mempot.gif)

Resting Potential

At rest there is a potential difference between the outside of the membrane of an axon and the inside. The usual value used is - 70mV. 

Outside is positively charged. Inside is negatively charged. 

Concentration of Na+(Sodium) is higher on the outside. 

Concentration of K+(Potassium) is higher on the inside. 

Both are positive so there is no potential difference. The distribution of Cl- makes the resting potential. This is maintained by the properties of the selectively permeable membrane. 

Action potential

Information travels down a neuron as an action potential. AP is generated by a stimulus of a receptor or from an AP from another connecting neuron. 

(http://click4biology.info/c4b/6/images/6.5/depol.gif)

1. Sodium pores suddenly open. 

2. The difference in concentration of sodium in and out, means the sodium diffuses in (helped by electrical forces) 

3. This influx of positive sodium ions makes the inside positive. 

4. this reduction…

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