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Unformatted text preview: long-distance signals that do not decrease in strength; in neurons , nerve impulses o only axons can generate action potentials (total change in voltage inside neuron of ~ 100mV (from -70mV to +30mV))- depolarization: inside of cell becomes less negative (e.g.: -70mV →-50mV)- hyperpolarization: inside of cell becomes more negative (e.g.: -70mV →-90mV) Action Potential:- resting state: voltage-gated channels closed; diffusion of sodium & potassium ions through leakage channels- depolarizing phase: increase in sodium permeability & reversal of membrane potential o local influx of sodium leads to slight depolarizations o fast sodium channel activation gates open quickly & sodium rushes into cell o more sodium channels open - positive feedback cycle o if threshold voltage (generally between -50mV & -55mV) is reached by sodium influx, all sodium channels open & action potential is generated o voltage inside cell becomes positive (about +30mV) page4...
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- Fall '10
- Anthropology, potassium ions, positively charged ions, sodium ion concentration, positive sodium ions