CAPS 301 Lecture Notes - Winter 2018 Lecture 3 - Saltatory conduction, Myelin
21 Sep 2018
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Falling phase: inactivation gate of na+ channels has closed. Activation gate of k+ channels if open. Ahp: activation gate of na+ channel is closed. Activation gate of k+ channel remains open. Repolarization from k+ conductance initiates the process of recovery. Na+ channels will remain inactivated in depolarized state until repolarization occurs. Conductance: movement of ions across the membrane g_na: change in conductance of na+ g_k: chance in conductance of k+ Absolute refractory period: membrane cannot fire an action potential again. Relative refractory period: membrane needs a greater stimulus intensity in order to fire another action potential. Needs to be a period of time between aps b/c not enough na+ channels open (na+ channel inactivation dominating) During depolarization, leak channels try to prevent this process. If enough na+ channels open, they overcome the leak channels. Distinguish between electrotonus and active propagation of electrical potentials. Describe factors influencing the active propagation of an action potential along an axon, including resistance and capacitance.
