Unformatted text preview: litude. the duration at which channel open varies with the normal distribution at some mean. basically channel is either on or off. what we are
looking through current of potassium ion through ion channel.
-change membrane potential:clamping means that you set the membrane potential at some level and you clamp it there (hold it there). here clamping
is hold at normal resting potential. in the next experiment, we will depolarize the membrane. Endolymph im
Patch clamping Time - 10 pA -0 100 ms top=at normal resting level. bottom=what signal ion channel look when depolarize.
use Olm's law: current (movement of charge),voltage (force making charge move), resistance( property that impede flow). current directly proportional to the
voltage driving the charge and inversely proportional to the resistance opposing the movement.
directly proprtional to the voltage driving the movement is the difference between membrane and equilibrium potential. if force is positive, negative=inward
think resistance in terms of conductance (opp. of resistance). the current carry by ion is =conductance xdriving force.
-conductance is not same as permeability (chemical term referring to mass of ions move across membrane). conductance (charge of ion move across
membrane) is an electrical term like resistance (1/R) Depolarization Affects Single Channel Currents
Open - i Closed conductance (g)=1/R I(ion)=g(ion)[Vm-E(ion)] Depolarization Current
Time Open Closed open more frequently. though time it increase is same. • Increase in probability
• Increase in amplitude
I is bigger For single
R i= Vm - Eion
R so you can see why
increased when you
the memory potential
with depolarization is
moving away from
for potassium, so
driving force increase.
the equilibrium is
more negative while
resting is more
postive than Ek. when
become even more
positive, driving force
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- Spring '09