BIOLOGY 3P03 Lecture Notes - Lecture 5: Wcen-Fm, Electrical Network, Lipid Bilayer
24 Sep 2017
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Bio3p03: membrane potential: ionic steady state ii (lecture 5) Equivalent circuit has two branches; the capacitor cm and resistor (labelled k) are arranged in parallel. (or g) refers to conductance which is actually the reciprocal of resistance (i. e. 1/r); Greek gamma () for single channel, g for whole cell conductance. Recall: ek is represented as a battery; here potential energy is stored and derives from the k+ concentration gradient across the membrane; driving force = vm - ek. Units : r is in ohms, g is in ohms-1 or siemens (s) Ohm"s law: v = ir: v = voltage (in volts, i = current (in amps, r = resistance (in ohms) Note: ohm"s law refers to a resistive current. Thursday, september 21, 2017: c = q/v. Q (in coulombs) = c (in farads) v (in volts: because current refers to the rate of ow of charge, then the capacitative current ic = dq/dt = c dv/dt (where c is constant)
