BIOLOGY 3P03 Lecture Notes - Lecture 9: Voltage Clamp, Tetraethylammonium, Membrane Potential
19 Oct 2017
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Document Summary
I. e. measures and injects current until threshold; measures how much current is needed to reach the membrane potential at that voltage and then the current needed to push past that point. Recall the parallel resistance and capacitance model: because r and c are in parallel, the total current owing across the membrane: im. Capacitative current ic = dq/dt = c dv/dt. Because if held at a certain voltage there is no change in voltage over time. Under a perfect voltage clamp, all current recorded by ampli er is ionic current. Note: im is total membrane current owing during clamp". Capacitative current- transient current- associated with changing vm from -65 to 0 mv, as charge is displaced on and o membrane capacitance. Gating current- tiny current associated with initial opening of channels (this is due to movement of positively charged s4 region of channel protein, during transition from closed to open con guration)
