PSYC 355 Lecture Notes - Lecture 7: The Sequence, Axon Hillock, Meninges
19 Sep 2018
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Document Summary
If you plot both currents on the graph, you will see one curve for the na+ channels opening and a separate curve for the k+ channels opening. The na+ curve plus the k+ curve gives us the action potential curve (depolarization, repolarization, undershoot and going back to 0). K+ channels open up later and over a longer period of time that na+ channels (the voltage regulation for k+ is different than na+). Biophysicists talk about these ion channels by describing the action of the ion; so whether there is inward current or outward current (which channels open to let current in, and which channels open to let current out). There"s about 4 subtypes and all are closed at rest. They open within one millisecond of threshold (-50mv to -55mv). All na+ channels are blocked by ttx (found in puffer fish). The subtypes of na+ channels can activate and inactivate slowly in cell bodies and dendrites.
