NEU 301 Lecture Notes - Lecture 6: Tetraethylammonium, Tetrodotoxin, Membrane Potential
Document Summary
Nernst: ena = 58 log (440/50) = 55 mv. *figured out early inward current driven my na+ Removal of external na+; conc gradient is reversed and current is reversed. Little effect on late current, suggests due to different ion (due to k+ efflux) Differences in time courses suggests there must be different mechanism for voltage- sensitive permeabilities. Calculate dependence of na+ and k+ conductance on time and membrane potential. Conduction velocity time required for signal to travel from one end to other. Nodes of ranvier: aps only occur at breaks in myelin. Summation of many small depolarizations at synapses reaches threshold at hillock. Triggering of ap due to positive feedback between "crowded" na+ channels that are less dense through rest of neuron. Control of neural activity in a mouse brain. Express membrane ion channels: open in response to light. In mouse brain, neurons firing controlled by light delivered by optic fiber.
