The cell membrane can be modeled as a plate capacitor, with the lipid membrane a

Question

The cell membrane can be modeled as a plate capacitor, with the lipid membrane as the insulator and the intracellular and extracellular fluid as conducting plates. It has been experimentally shown that biological membranes typically have a capacitance of 1 mu F per square centimeter of membrane. Use the definition of capacitance with Faraday's constant to determine the charge and the number of moles of excess ions stored on 1 cm^2 of each of the following membranes: Smooth muscle cell, with a resting intracellular potential of -50 mV to -60 mV. Large nerve fiber, with a resting intracellular potential of -90 mV. Large nerve fiber, with an "overshoot" action potential of +35 mV.

Explanation / Answer

C= 1 micro F

f= farady constant=9.64*10^4 C/mole

a) V = potential = -50 mv to-60 MV

Q= charge = C*V

Q=-50 mC to -60 mC per cm^2

N= number of moles =Q/f= 5.18*10^-7 to 6.22*10^-7

b) Q=90*1= -90 mC. Per cm^2

N= number of moles= Q/f=9.33*10^-7 moles

C) Q= 35 mC

N=Q/f= 3.63*10^-7 moles

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