An action potential is propagated down a neuron by means of several sodium and potassium channels and pumps. Normally, each section of neuron has a resting membrane potential of -90mV. This potential...

An action potential is propagated down a neuron by means of several sodium and potassium channels and pumps. Normally, each section of neuron has a resting membrane potential of -90mV. This potential is created by a Na+/K+pump, which pumps three Na+ ions out of the cell for every two K+ ions pumped into the cell, and by K+/Na+ leak channels, which are 100 times more permeable to K+ than to Na+.The potential difference change during an action potential is shown in Figure 5.43.

(a) If the concentrations of Na+ and K+ for the equilibrium state of the cell are shown in Table 5.10, what is the contribution of the ions to the resting membrane potential of the nerve? Does this answer differ from the expected resting potential? Explain.

(b) As mentioned in the cell membrane can be modeled as a capacitor. The equation for the definition of capacitance can be differentiated with respect to time to determine the current across the capacitor. Use to determine the current through 1cm2 of the neuron membrane during depolarization and repolarization. What is the rate of sodium and potassium ions passing through 1cm2 of the membrane during depolarization and repolarization? Recall that the charge of a proton is 1.6 10^-
19C and that biological membranes typically have a capacitance of 1mF per square centimeter of membrane.