Membrane potentials

Membrane potentials - long-distance signals that do not...

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Membrane potentials: - resting membrane is polarized - the inside of the neuron is negative with respect to the outside (fewer positively charged ions) - sodium ion concentration is higher outside cell than inside; potassium ion concentration is higher inside cell than outside - positive sodium ions outside neuron balanced with (-) chloride ions; positive potassium ions inside neuron balanced with negatively charged (anionic) proteins with excess negative charge - the voltage in a resting neuron is between -40 mV & -90 mV potassium back into cell - graded potentials: short distance signal; local changes in membrane potential that decrease in strength with distance (fade quickly) o generator potential: excitation of sensory neuron by energy o postsynaptic potential: stimulation by neurotransmitter released by another neuron - action potentials:
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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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Membrane potentials - long-distance signals that do not...

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