KINE 2031 Lecture Notes - Lecture 10: General Mills, Saltatory Conduction, Axon Hillock
2 Jul 2018
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Reversal of Membrane Potential
-Triggering events causes resting membrane (-70mv) to depolarize until it reaches
threshold potential (-50mv). At threshold, explosive depolarization takes place t0
+30mv. Just as rapidly, membrane drops back to resting potential causing brief
hyperpolarization, where it becomes more negative than resting (-80mv), before resting
potential is restored
-Duration of AP is same in excitable cell. AP are longer in muscle cells than nerve cells
-Threshold is critical all-or-none point.
Changes in Membrane Permeability
-K+ makes greatest contribution to establishment of
resting potential, because membrane is more permeable to K+
than Na+
-Action potentials takes place as a result of triggered opening
& closing of two types of channels:
oVoltage-gated Na+ channels
oVoltage-gated K+ channels
Voltage Gated Na+ & K+ Channels
-Voltage gated Na+ channels have two gates: activation & inactivation gate. 3
Conformations:
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Document Summary
Triggering events causes resting membrane (-70mv) to depolarize until it reaches threshold potential (-50mv). Just as rapidly, membrane drops back to resting potential causing brief hyperpolarization, where it becomes more negative than resting (-80mv), before resting potential is restored. Duration of ap is same in excitable cell. Ap are longer in muscle cells than nerve cells. K+ makes greatest contribution to resting potential, because membrane is more than na+ Action potentials takes place as a result of. & closing of two types of channels: voltage-gated na+ channels, voltage-gated k+ channels establishment of permeable to k+ triggered opening. Voltage gated na+ channels have two gates: activation & inactivation gate. Conformations: closed but capable of opening (activation gate closed & inactivation ope, open or activated (both gates open) Voltage gated channel has one gate: can either be open or closed. Na+-k+ pimp and leaks channels restore concentration gradient. Changes in permeability & ion movement during action potential.
