lecture 4 action potential

lecture 4 action potential - 9/15/2008...

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9/15/2008 1 Lecture 4: Action Potential Overview 1 Review 1. Review 2. Sodium/Potassium Pump 3. The Action Potential 4. The Neural impulse Review Communication in neurons involves an electrochemical signal and is one of several types axondendritic, axosomatic, axoaxonic, dendrodentritic, or neuromuscular Microelectrodes can be used to record the electrical potential of a neuron The resting membrane potential (RMP) of a neuron is 70mV (more negative on the inside relative to the outside) Two factors contribute to the RMP Membrane permeability Distribution of ions. Influenced by: Diffusion – Movement from a high to a low concentration Electrostatic pressure–a t t ra c t
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9/15/2008 2 Activity in neurons (activity in brain) We read activity by recording “firing” or action potentials Action potentials are very quick large electrical pulses generated by neurons. Characterized by a rapid reversal of the membrane potential from 70mV to +55mV in response to a stimulus (either graded potentials (will talk more about these later) or positive current injected via a microelectrode). Action potentials are voltage dependent and “ all or none ” (they either reverse the membrane potential or not (they either reverse the membrane potential or not and are always the same size). The action potential only refers to changes in membrane potential of the axon, not to the dendrites or the cell body.
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lecture 4 action potential - 9/15/2008...

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