BIOL 1412 Lecture Notes - Axon Terminal, Axon Hillock, Membrane Potential

• School: University of Manitoba
• Department: Biological Sciences
• Course: BIOL 1412
• Professor: Paul Messing

Document Summary

* a large change in mp that propagates along an axon with no change in intensity. * initiates at trigger zone eg. axon hillock of multipolar + bipolar neurons; just past dendrites of unipolar neurons. 1) = gp - membrane potential at the axon hillock reaches - 55mv. 3) repolarization phase (repol. : na+ channels close become inactivated (decreased na+ permeability) na+ movement returns to resting levels, voltage-gated k+ channels open (increased permeability) therefore, k+ diffuses out (+ve charges (k+) move out - decreases mp) 4) after-hyperpol. phase (below the rmp: k+ channels are slow to close and remain open longer than necessary, na+ channels are reactivated - can respond to stimuli at this point. * once k+ channels close mp returns to rmp (fig. * note: na+/k+ -atpase always working to maintain gradients. * takes 10 000s of aps to cause a measurable change in [ion] in the cell: refractory periods of an ap: (fig.