Please answer part e through h, thank you!
We can model this depolarization and repolarization process in one section of the axon membrane using a circuit with two resistors and (R_{2}), two batteries and (|Delta V_{2}|), and a switch ((SW_{1})). Point d corresponds to the outside of the cell, and point h corresponds to the inside of the cell. (Points d and h are not externally connected to anything.) We have defined (Delta V_{membrane}=V_{inside}-V_{outside}), so in this circuit the membrane potential is the difference between the electric potential at points d and h: (Delta V_{membrane}=V_{h}-V_{d}).
We'll first analyze the circuit when the switch is open. When the switch is open, the only path between points d and h is on the left side of the circuit.
b. Without doing any calculations, what is the current in the circuit? Explain how you can tell. When the switch is open, the circuit is open and a isn't connected, this would make the current, (I=0).
c. What is the potential difference across each of the resistors? Explain how you can tell. When the circuit is open, there isn't a path for the current to flow. This will result in potential difference across the resistors = 0.
d. Which point, d or h, is at a higher electric potential when the switch is open, and which point is at a lower potential? Does an open switch correspond to the resting state or the depolarized state of the membrane? What should (Delta V_{membrane}) be equal to for this state of the membrane?
The current will move from a to h. (Delta V_{membrane}) will be equal to (R_{1}Delta V_{2}). Point h will have a higher electric potential because it is positive than point d, which is negative when the switch is closed.
e. Write an equation that applies Kirchhoff's third principle to the left path of the circuit: start with 0V at the lower potential point, add the potential rises and subtract the potential drops along the left side of the circuit, and set this equal to the higher potential point (which will be (|Delta V_{membrane}|).
f. Use your equation from part e to find the electric potential difference of battery 1, (|Delta V_{1}|).
Now we will analyze the circuit when the switch is closed. We determined above that the open switch circuit corresponded to either the resting state or the depolarized state of the membrane; the closed switch therefore corresponds to the other state. When the switch is closed, there are two paths between points d and h. We will use (R_{1}=90kOmega) and (R_{2}=10kOmega).
g. Predict the direction of the electric current in the circuit. Explain your reasoning.
h. What should (Delta V_{membrane}) be equal to for this state of the membrane? Which point, d or h, is at a higher electric potential when the switch is closed, and which point is at a lower potential?