Lecture__10_09

Lecture__10_09 - III.C.1. Properties of voltage gated (VG)...

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III.C.1. Properties of voltage gated (VG) Na + channels 4 units Looking down through the pore of a voltage gated sodium channel CLOSED OPEN INACTIVE STATE MUST REPOLARIZE BACK TO ~ THE RESTING MEMBRANE POTENTIAL DEPOLARIZATION TO A VOLTAGE ABOVE THE CHANNEL'S THRESHOLD (~ -40 mV) Channel State State of inactivation gate Na + flow? (YES or NO) Ready to open? Energetically sta- ble or unstable? Membrane Potential CLOSED OPEN INACTIVE STATE AFTER ~ 1 MILLISECOND, INACTIVATION GATE BLOCKS FLOW THROUGH CHANNEL Inactivation Gate of protein The VG K+ channels in the squid giant axon are similar to the VG Na+ channels we just described except 1) The VG K+ channels (in squid giant axons) have slightly higher thresholds 2) The VG K+ channels (in squid giant axons) are slow to open. (Usually there is a ½- 1.5 m.s delay between their crossing threshold and opening) 3) The VG K+ channels (in squid giant axons) do not have inactivated states (although protein sub-units associated with gates are present). III.C.2. Properties of VG K
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This note was uploaded on 11/22/2009 for the course NPB 100 taught by Professor Chapman during the Fall '08 term at UC Davis.

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Lecture__10_09 - III.C.1. Properties of voltage gated (VG)...

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