PGY 300 Lecture 4: Neurophysiology - Action Potentials
11 Feb 2017
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Document Summary
Open channels charges might go into neuron. Open more channels bigger change in voltage/depolarization. At the site of synapse where stimulus occurs, we get a big depolarization (cell was resting at -70 mv) Full magnitude of signal won"t get down entire cell since charges will leak out through membrane. Not good at sending signals long distances. Important at synapses to code information about strength of stimulation and what kind of stimulus it is. Travel long distances quickly at same size. Graded potential fades but action potential does not. Stronger graded potential higher frequency of action potential. Strength of stimulus is encoded by size of graded potential but encoded by frequency of action potential. Won"t be produced if graded potential doesn"t reach threshold (-55 mv) at trigger zone. If large graded potential is created (due to more channels being open), it may produce signal that will be above threshold at trigger zone creates action potential.
