#11 Flashcards
Current Equation
Iion = gIon (Vm - Eion)
Resting Potential
Can be found by combining conductances
Vm = Vrest when Ik+Ina+Icl = 0
Voltage Clamp Theory
Variable battery to control the voltage in a circuit while we measure current
Parallel Conductance Finds..
Vrest Given conductances (g) and Equilibriums (nernst)
If Voltage Clamp (VCommand) is held to Vrest…
No net current through channels and across capacitor
IV Plot
Current v Voltage
Changes in voltages produce changes in current
Total Current Flow (gInput)
Ionic conductance can be reduced to single conductance
gInput
Itotal =
= gInput (Vm - Vrest)
Vrest found with PCE
Current Flow Through gInput
ALL current flow will be through gInput
This will determine plot of graph
Plot will be…
Straight Line
I = 0 when Vm = Vrest (no net current!)
Slope =
gInput
iTotal Components Sum…
Linearly for each ion that is permeable
Two Ways to Determine Vrest
- PCE
- Plotting iK and iNa as a function of voltage and finding the Vm where Ik is as much above x-axis as below x-axis
ie where iK = -iNa, thus iTotal = 0 (Vrest)
Reversal Potential (Zero Current Voltage)
Potential at which the current being considered reverses direction (goes from inward to outward with respect to voltage).
Exists for both Eion and Vrest (total)
If Vm is more negative than Vrev…
Current flows inward
If Vm is more positive than Vrev…
Current flows outward
