Exam 2: Ch 5 Book Electrical Properties & Equations Flashcards
the plasma membrane is impermeable to ions and therefore is an _______
insulator
two conductors separated by an insulator form an _______ _______
electrical capacitor: a device that can store energy in the form of separated electric charges
amount of electrical charge stored on the two sides of a capacitor is measured in units of…
farads (F), coulombs per volts
what gives the membrane its electrical conductance
channel proteins that allow ions to pass
electrical ______ and electrical _____ both characterize how readily charges can move in a circuit
resistance (R), conductance (g)
what is the resistance of a membrane
measure of its impermeability to ions
equal to the inverse of conductance R=1/g
for a given transmembrane voltage, the lower the resistance…
the higher the conductance
the more ionic charges will cross the membrane through open ion channels per unit time
Ohm’s law
the voltage drop produced across a membrane by a current that passes through it is directly proportional to current times resistance of the membrane
ΔVm = ΔI x R
shows relationship between current, resistance, and steady-state voltage
units of Ohm’s law
ΔVm (volts) = the voltage drop across the membrane
ΔI (amps) = current across the membrane
R (ohms) = electrical resistance of the membrane
input resistance
total resistance encountered by current flowing in or out of the cell
what does input resistance depend on
surface area of cell memb. (A) b/c membrane of a larger cell has more ion channels
density of channels per unit area
capacitative current
ions interacting across a membrane
when voltage applied, ions build up on either side and interact
dielectric constant
property that reflects the inherent ability of an insulator to store charge
amount of charge separated by a layer of insulation depends on…
its thickness
dielectric constant
the capacitance of a membrane affects…
how it responds to change in applied voltage or current
