BMS 870 Lecture Notes - Lecture 3: Action Potential, Axon Hillock, Optical Fiber
28 Oct 2017
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K+ associated w/ 4 water molecules = interact w/ channel, h20 stripped off k+, k+ can interact w/ oxygens = can go through pore -> hydrated again. If you change aa of core, can change properties of channel. Inside of neuron is -ve charged compared to outside. Rising phase - vg na+ channels open and na+ flows inside neuron, resulting in increasing +ve charge inside. Overshoot - membrane potential reaches 0 mv as more na+ channels open and allow na+ in (positive feedback). Falling phase - k+ channels open and k+ flows out. Microelectrodes - measure potential difference bw inside and outside the axon relative to the ground. Can now be used on tiny neurons, initially large (squids, other invertebrates). Detectors often connected to amplifier resulting in a sound generated by an oscilloscope. Depolarization (closer to 0 mv) results from influx of na+, repolarization from an efflux of k+. Stimulation of multiple ap"s: microelectrode artificially injects current into neuron (electrophysiology).
